Summary Part2 Firewalls

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FROM:
Eric Nowak
jvncnet!reston.ans.net!nowak

Offers a commercial product known as interlock.
He also sent along the white paper (Interlocker)
enclosed.
-----------------------------------------------
FROM:
Houman Safai
Systems Administrator
hsafa@esri.com
ESRI

Offers the white paper on Unix Security below.

_________________________________________________

Well I hope this reaches everyone. Good Luck!

Thanks to all again who responded, you made a lot of
people happy!!!

================================================================================
John Ciesla Voice (w/mail): 609-520-5105
Dow Jones & Co., Inc. Fax: 609-520-5089
Engineering Department
                            Internet: jc@eng.dowjones.com
P.O. Box 300
Princeton, NJ 08543-0300
                            
Route 1 & Ridge Road
South Brunswick, NJ 08852

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         ANS CO+RE Systems, Inc.

         White Paper

         InterLockSM 2.1

         1. Introduction

         This paper provides an overview of the design and
         implementation of the InterLock. This document includes an
         overview of the original design goals followed by a summary
         of major enhancements in release 2.1. Later sections
         describe the hardware requirements, implementation details,
         and the InterLock service model. Information on ANS CO+RE
         Systems is provided at the end of this document.

         2. Goals of the InterLock

         The InterLock was designed to provide application gateway
         services between two IP networks. The InterLock software
         controls access between networks and prevents configuration
         information about the private network (hostnames, IP
         addresses, domain names) from being propagated to any public
         network. In addition to the traditional firewall approach
         of controlling access based on protocol and
         source/destination address, the InterLock provides user
         level authentication and logging. That is, instead of
         allowing all TELNET connections from a particular IP
         address, the InterLock administrator can define a security
         policy which specifies that ONLY jsmith is allowed TELNET
         access from a particular host. In the typical
         configuration, the InterLock would be physically situated
         between an organization's private enterprise network and
         their connection to the Internet (shown in Figure 1).

         __________

         InterLockSM is a servicemark of ANS CO+RE Systems, Inc.

              __________________________________________________

*** INSET ***

          Figure 1. InterLock separating private network from public
                                   Internet

              __________________________________________________

         However, the InterLock can just as easily be used to protect
         portions of an organization's internal network. In the
         example shown in Figure 2, the InterLock is used to protect
         the Finance LAN from unauthorized access by users from other
         organizations (e.g. Research and Marketing) on the internal
         corporate network.

              __________________________________________________

*** INSET ***

         Figure 2. InterLock used to control access between internal
                                 IP networks

              __________________________________________________
         2.1 Terminology

         Throughout this paper, the terms private and protected
         network will be used synonymously. A public network will
         refer to any unprotected network. In Figure 1 above, the
         public network is the Internet. In the second example,
         Finance is designated as the private (or protected) network.
         Research and Marketing, as shown in figure 2, form the
         public network.

         2.2 Design Goals

         The InterLock offers an alternative to the packet filtering
         approach common in most router-based Internet firewalls.
         The InterLock was designed and developed to satisfy the
         following requirements. InterLock 2.1 features are noted in
         square brackets [2.1].

             7 The system should not act as a packet filter or
                router.

             7 Application gateway services should exist for TELNET,
                SMTP, FTP, NNTP and X Windows.

             7 The InterLock should be capable of acting as an
                Network Time Protocol (NTP) Server for the private
                network. [2.1]

             7 Administrators should be able to control the
                direction(s) when each service can be used. This
                control is based on a user or group, service,
                protected/unprotected host or network, time of day,
                and day of the week.

             7 It should be possible to group users together and
                apply rules to groups as well as individual users.
                It should be possible for a user to be a member of
                multiple groups. [2.1]

             7 The InterLock should support other types of user
                authentication in addition to traditional UNIX
                passwords (e.g. smart card technology).
                Administrators should be able to define combinations
                of authentication types and the order in which they
                are applied (e.g. user must enter UNIX password
                followed by SecurID information when TELNETing
                outbound). [2.1]

             7 InterLock-To-InterLock encryption using industry
                standard encryption and key management techniques
                should be available.

             7 The InterLock should be capable of acting as an SMTP
                mail gateway for an organization.

             7 Information about the protected network should be
                hidden from external users and hosts.

             7 Detailed logging information should be generated for
                each service describing every security relevant user
                action.

             7 User-friendly interfaces should exist to simplify
                system administration.

             7 The InterLock should be provided as a turn-key leased
                service with 24 hour a day, 365 day a year support.

         3. Hardware

         The standard hardware configuration of the InterLock is an
         IBM RS/6000 320H running a modified version of AIX 3.1.5.
         Each system is configured with a 400 MB hard drive and 16 MB
         RAM. The Interlock is a dual-homed device with 2 network
         interfaces. The InterLock is connected through one network
         interface to the public network. The second interface
         allows the InterLock to access the private (or protected)
         network. Currently supported network interfaces include
         Ethernet, Token Ring, and FDDI.

         4. How Does The InterLock Work?

         Previous sections of this paper listed the requirements
         driving the design of the InterLock. This section provides
         details on the implementation of those capabilities.

         4.1 No IP Forwarding

         The InterLock is based on a modified version of AIX 3.1.5.
         The primary change to the operating system (OS) kernel was
         to remove IP forwarding. With this capability removed,
         there is no way for the InterLock to forward a packet
         directly from one network to another (i.e. no way for the
         InterLock to act as a router). Instead, software daemons
         are provided which listen for connection requests on
         specified TCP ports and provide necessary proxy services.
         InterLock daemons are started from inetd.


         4.1.1 ICMP Redirects Ignored

         A second change to the OS kernel was the modification of
         code associated with the handling of ICMP redirects. The
         InterLock ignores all ICMP redirect requests.

         4.2 No Dynamic Routing Protocols Supported

         The InterLock does not support any dynamic routing protocol
         (RIP, gated, OSPF). Instead, the administrator must
         statically define necessary routes. In the standard
         configuration, a default route is created which points to
         the organization's public-side router (e.g. router to the
         Internet) and static routes are defined for each of the
         organization's internal subnets. By not allowing the
         InterLock to learn routes, the risk associated with a number
         of security attacks (e.g. route spoofing, denial of
         services) can be minimized.

         4.3 No "r" Commands Supported

         The "r" commands (rsh, rlogin, rexecd) are not supported on
         the InterLock. These applications are removed from the
         system during the initial configuration. A optional
         security-enhanced version of rcp can be installed on the
         system. This utility allows InterLock administrators to
         automatically transfer non-root owned files to/from hosts on
         the protected network.

         4.4 The Access Control Rule Base (ACRB)

         The InterLock is a security enhanced application gateway
         between IP networks. Each application makes appropriate
         queries to the ACRB to determine if a connection request
         should be granted and, if so, the level of service which
         should be provided. Through a menu-driven interface1,
         InterLock administrators define a set of rules which
         describe the organization's security policy. The general
         model of the InterLock is that which is not expressly
         permitted is denied. Therefore, rules need to be added
         which provide a user (or group of users) access to a
         particular service (TELNET, FTP, etc.).

     1. A command line interface is also available.


         There are two components to each rule. The first portion of
         each rule describes the situations when the rule is to be
         enforced. Rules which do not match a particular situation
         (e.g. outside the time range) can be configured by the
         administrator to deny access or simply remain inactive. The
         second part of each rule defines the authorizations or
         constraints to be enforced.

         Directional use of a service can be denied/granted using any
         of the following criteria:

             7 User or Group
             7 Service/Protocol
             7 Source/Destination Host or Network Address
             7 Time of Day (start/stop times)
             7 Day of the Week

             Rule Constraints

             7 Direction of Connection/Data Flow
             7 Authentication Type(s)
             7 Encryption Required (optional)

         It is possible for an administrator to create a rule which
         allows the user jsmith to TELNET from any host on the
         private network to remote.customer.com on the public network
         between the hours of 9:00 a.m. and 5:00 p.m. Monday through
         Friday using standard password authentication. The
         direction parameter allows an administrator to specify that
         jsmith can TELNET FROM an internal host TO remote but not TO
         an internal host FROM remote.

         4.5 User Group Support

         Rules can be created for and applied to individual users,
         group of users, or to the entire user community (using a
         wildcard entry). It is possible to create a separate set of
         rules for each user on the system. However, it is usually
         easier to group users together, creates rules for that
         group, and have each user inherit the associated rules.
         Group support has been integrated into the ACRB and other
         utilities to ease system administration. Users can belong
         to multiple groups. When an application queries the ACRB to
         determine if a particular connection request should be
         granted, it first checks to see if there is a specific rule
         for the user. If no user rule exists, the application
         checks for rules associated with groups containing the user.
         If the user is a member of multiple groups and there are
         rules for more than 1 of those groups in the ACRB, the
         "maximum of the minimums" permissions are granted. The
         rules for each group are queried separately and the most
         specific rule matching the search criteria is determined for
         each group. Then the rulebase grants the privileges
         associated with the most permissive of the "specific"
         matching rules.

         4.6 TELNET and FTP

         TELNET and FTP gateways exist on the InterLock. Users on
         one side of the InterLock wanting to access a host on the
         other side of the InterLock must first connect to the
         InterLock and authenticate themselves. The InterLock TELNET
         and FTP daemons listen on the well-known ports associated
         with their respective protocols (e.g. 23 for TELNET).
         Customers may change the port associated with a service, if
         desired. The following example (shown in Figure 3) describes
         the interaction between the service, user authentication,
         and the ACRB.

         The user jsmith wants to establish a TELNET connection from
         hostA on the internal network to remote on the public
         Internet.

              __________________________________________________

*** INSET ***

                   Figure 3. Example Network Configuration

              __________________________________________________

         The user (on hostA) first initiates a TELNET session with
         the InterLock. The TELNET daemon on the InterLock receives
         the request and queries the ACRB to determine if TELNET
         connections are allowed from hostA at the current time and
         day of the week. If the connection is allowed the user is
         prompted for username and password. If the InterLock was
         configured with the SecurID option, the password prompt
         shown below may be followed by, preceded by, or replaced
         with prompts asking for the user's PIN and card display
         code.

             InterLock login: jsmith
             jsmith's password:<Password not displayed on screen>

         If jsmith correctly enters his password, the TELNET daemon
         again queries the ACRB to determine if jsmith is allowed to
         TELNET from hostA. If so, the user is prompted for the
         remote destination.

             InterLock Telnet Gateway 2.1(interlock.widget.com)
             Destination [interlock.widget.com]> remote.customer.com

         The ACRB is then queried a final time. This check
         determines if the user jsmith can TELNET from hostA to
         remote. If access is allowed then a remote connection is
         established to remote and the user will receive the normal
         login prompt. Had any ACRB checks failed along the way,
         the connection would have been terminated.

         Each query into the ACRB includes an associated check to
         determine if the action can be performed at the current time
         and day of the week. The TELNET login and destination
         prompts can be modified by the customer to meet their
         specific needs.

         FTP works in the same basic manner as TELNET. The user
         established an FTP connection to the InterLock,
         authenticates with username/password (or SecurID
         information), and then issues the USER command to specify
         the user and host for the desired destination. The user is
         then prompted for a password on the destination host.
         Throughout this process, FTP makes queries into the ACRB to
         determine if the service request should be granted. Figure 4
         shows a sample FTP connection request. Administrators can
         define rules in the ACRB which limit the operations a user
         can perform with FTP (e.g. user can get files but not put
         them).


                __________________________________________________

             [hostA:78]ftp interlock
             Connected to interlock.widget.com.
             220 interlock.widget.com InterLock FTP Gateway 2.0 ready
             at Mon Jan 18 11:13:27 1993.
             Name (interlock:jsmith): jsmith
             331 Password required for jsmith.
             Password: <password not displayed>
             230- You are authorized as InterLock user "jsmith".
             Specify
             your the remote user
             230 and destination with the USER command (for example:
             USER remoteuser@remotehost)
             ftp> user anonymous@remote.customer.com2
     2. Previous releases of the InterLock required that the quote site
     <hostname> command be used when connecting to remote hosts. Current
     InterLocks provide backward compatibility with the quote command
     syntax.

             331-remote.customer.com FTP server (Version 4.1 Sat Nov
             23 12:52:09 CST 1991) ready.
             331 Guest login ok, send ident as password.
             Password: <password not displayed>

                         Figure 4. Sample FTP Dialog

              __________________________________________________

         4.7 SMTP Gateway Service

         In addition to TELNET and FTP application gateways, the
         InterLock can act as a store-and-forward SMTP gateway. The
         InterLock runs a modified version of sendmail which
         incorporates the concept of a mail mapping entry. Unlike
         TELNET and FTP, there is no password authentication of a
         user's SMTP session. The InterLock mailer (by default)
         consults a mapping database to determine where to deliver
         incoming mail from public hosts. This same database is used
         to verify that the address contained in the FROM: line of
         the message header is allowed to send mail. A sample mail
         mapping entry for jsmith might look like:

             jsmith: joesmith@hostA.widget.com,
             smith@pluto.widget.com

         The left hand side of the mapping entry defines the user's
         external mail address (e.g. jsmith@widget.com). The first
         entry on the right hand side is the address where incoming
         mail for jsmith will be delivered (i.e. mail which arrives
         addressed to jsmith@widget.com will be delivered to
         joesmith@hostA.widget.com). Right hand side (RHS) entries
         define valid sending addresses for the user. That is, mail
         which arrives from the private network with the address
         joesmith@ hostA.widget.com or smith@pluto.widget.com will be
         remapped and the resulting message will be sent from
         jsmith@widget.com. Inbound mail which arrives addressed to
         joesmith@widget.com would be rejected because there is no
         corresponding left-hand side entry in the mail mapping file.

         The goal of this remapping approach is two-fold. First, it
         provides a mechanism to provide selected users with mail
         access while denying others and, secondly, the remapping
         removes references to internal hostnames on outbound
         messages. All InterLock services, including mail, are
         integrated with the ACRB. Therefore, it is possible to
         create rules which allow/disallow SMTP traffic between
         specified hosts or networks. One added benefit of remapping
         on the InterLock, is that this feature can be used to
         establish a common e-mail naming convention across an
         organization (even if none previously existed).

         Mail can be configured to pass-through the InterLock without
         requiring associated mapping entries. However, in order for
         replies to work correctly, internal host names must be
         revealed in outbound message headers. Pass-through mailing
         eliminates the administrator's ability to filter mail on a
         per-user basis.

         4.8 InterLock X Service

         The InterLock can be optionally configured to support
         X-Window applications through the InterLock. The InterLock
         X daemon (startX) acts as a combination pseudo-X
         server/X-client. Consider the network configuration
         described in Figure 4. In this new example, jsmith wants to
         have an X-client application (e.g. xterm) running on
         remote.customer.com display on his workstation, hostA.
         Jsmith first TELNETs to the InterLock and LOGS IN to the
         system. When a user logs in to the InterLock, they are
         placed in a restricted login shell. Although, the user has
         an account on the system, there is no disk space or file
         save capability associated with the account. The user then
         executes the startX command with a single parameter
         identifying where the X-application should be displayed.
         The InterLock will then display a message similar to that
         shown in Figure 5 below.


               __________________________________________________

           interlock.widget.com: startX hostA:0

           interlock.widget.com will now accept X connections for
           screen 117.

           Telnet to the machine which has your X client and use this
           host
           and screen number in the display argument of your X
           client. e.g.:

                           xterm -display interlock.widget.com:117

           This server will shutdown if not used within the next 3
           minutes.

           This server will shutdown after 20 minutes of inactivity.

                       Figure 5. Sample StartX Session

              __________________________________________________

         The user then initiates a TELNET session to remote. After
         logging in to that host, jsmith then starts up the X-client
         using the pseudo-server identified in the startX output. In
         this example, jsmith has 3 minutes to establish a connection
         to the InterLock server 117.

             interlock.widget.com: telnet remote.customer.com

         After logging in to remote, jsmith would run the following
         command.

             remote: xterm -display interlock.widget.com:117

         The InterLock X daemon will then read in X-packets from
         remote (on port 6117) and display them on hostA:0. For this
         to work properly, jsmith would have had to first enter the
         command xhost +interlock on his workstation, and there would
         have to be associated LOGIN, TELNET, and X rules in the ACRB
         allowing all of the necessary connections. If the InterLock
         daemon does not see any X traffic between those hosts over a
         20 minute period, the associated connection will be shut
         down. The 3 and 20 minute timeout periods are defined by
         the system administrator in the InterLock configuration file
         (see section 4.10)

         4.9 InterLock News Service (NNTP)

         The InterLock implements a NNTP forwarding daemon. Most
         customer sites maintain (or have access to) a network news
         server on the public side of their network (as shown in
         Figure 6).

              __________________________________________________

*** INSET ***

                 Figure 6. Example NNTP Network Configuration

              __________________________________________________

         The InterLock is configured by the administrator to point to
         the public news server (see NNTP_Public in Section 4.12).
         The users then have their internal news readers point to the
         InterLock as their newsserver (this is typically done by
         adjusting a configuration setting with the news reader or
         setting the NNTPSERVER environment variable). Assuming
         appropriate rules exist in the ACRB, the InterLock nntpd
         daemon will transfer NNTP traffic between the news reader
         and news server on opposite sides of the InterLock. NNTP
         does not currently include user authentication as part of
         the protocol. Therefore, the ACRB controls NNTP access by
         source/destination IP address, time, and day.

         4.10 InterLock Network Time Protocol (NTP)

         The InterLock can provide a reliable source of time for the
         private network. Internet-connected InterLocks will
         synchronize with stratum 1 and 2 time servers maintained by
         ANS CO+RE Systems, using the authentication mechanisms
         associated with NTP.

         4.11 Sample Log File Entries

         The InterLock runs a modified version of the syslog daemon.
         Each service generates logging information which allows an
         administrator to generate usage statistics, isolate
         configuration problems, and determine if there has been any
         attempts to obtain unauthorized access to the protected
         network. Log entries contain information on the service,
         the time the action occurred, a unique process id associated
         with the connection, the type of message (A-Alert,
         I-Information, etc.), the IP addresses of the hosts on
         either end of the connection, the user accessing the
         service, and an informative message. FTP log information
         includes information on the operation performed (put or get)
         and the file being transferred. Sample log entries are
         shown in Tables 1 and 2.

               __________________________________________________

           Jan 24 07:23:39 interlock loginout[8663]: IL:A:2:Login
           Failure:26_User=:28_Port=/dev/pts/1:51_Host=ts.widget.com
           Jan 24 09:33:03 interlock loginout[6469]:
           IL:I:103:Connection
           authorized:26_User=jsmith:50_Interface=192.77.167.2:51_Ho-
           st=
           hostA.widget.com:
           Jan 24 09:58:14 interlock loginout[3748]:
           IL:A:2:Unauthorized
           connection:26_User=king:50_Interface=192.77.167.2:51_Host-
           =hoops
           .widget.com:60_Auth=0 :61_Dir=2
           Jan 24 10:33:03 interlock loginout[6469]:
           IL:I:102:Login:26_User=jsmith:28_Port=/dev/pts/1:51_Host=-
           hostA.
           widget.com

                      Table 1. Sample Login Log Entries

              __________________________________________________

               __________________________________________________

           Jan 22 15:40:21 interlock ftpd[8621]: IL:I:100:Connection
           Open:50_Interface=192.77.168.250:51_Host=192.77.16813
           Jan 22 15:40:22 interlock ftpd[8621]: IL:I:102:FTP User
           Logged In:51_Host=hostA.widget.com:26_User=jsmith
           Jan 22 15:53:08 interlock ftpd[8621]: IL:I:130:Opening
           Remote Connection:52_Destination=ftp.gnu.ai.mit.edu
           Jan 22 15:53:08 interlock ftpd[8621]: IL:I:131:Remote
           Connection Open:52_Destination=ftp.gnu.ai.mit.edu
           Jan 22 15:54:03 interlock ftpd[8621]: IL:I:141:Command
           Successful:30_Command=RETR:31_File=/pub/kerberos/src.sp
           lit/Index:
           Jan 22 15:54:04 interlock ftpd[8621]: IL:I:141:Command
           Successful:30_Command=RETR:31_File=/pub/kerberos/src.sp
           lit/Index.~1~:
           Jan 22 15:54:40 interlock ftpd[9902]: IL:I:101:Connection
           Closed:50_Interface=192.77.168.250:51_Host=192.77.168.13

                      Table 2. Sample FTP Log Entries

              __________________________________________________


         4.12 InterLock Configuration File

         The administrator edits a configuration file when adjusting
         a number of system-wide parameters. A sample configuration
         file (/interlock/config/ILconfig) is provided below.

              __________________________________________________

         #
         # Public Interface Name
         #
                 Public_Interface en0
         #
         # Interface Addresses
         #
         # Private_Address 131.131.205.1
         # Public_Address 192.5.220.2
         #
         # TELNET Configuration Options
         #
                 Max_TELNET_login_failures 3
         #
         # FTP Configuration Options
         #
                 Max_FTP_login_failures 3
         #
         # X Configuration Options
         #
                 StartX_timeout_minutes 3
                 X_Inactive_timeout_minutes 10
         #
         # NNTP Configuration Options
         #
                       NNTP_Public news.widget.com
                       NNTP_Private news.widget.com
                 NNTP_DomainName widget.com
                 NNTP_Post_Header_RemappingOn
                 NNTP_Use_Mailmaps Off
         #
         # Authentication Options
         #
                 Authentication_List password securid
                 Securid_Server aceserver.widget.com

                Figure 7. Sample InterLock Configuration File

              __________________________________________________


         4.13 Supported Authentication Types

               7 InterLock supports password and SecurID.3 card

     3. SecurID and Security Dynamics are registered trademarks of
     Security Dynamics Technologies, Inc. All Rights Reserved.

               7 SecurID support for TELNET & FTP

         The InterLock can support multiple authentication mechanisms
         simultaneously. Currently, the InterLock supports
         traditional UNIX password authentication and the SecurID
         card from Security Dynamics.. Support for other token-based
         authentication cards will be included in later releases.
         The list of valid authentication types are defined in the
         InterLock configuration file (see 4.12). Because
         authentication type has been fully integrated into the ACRB,
         the administrator can specify the type of authentication
         required on a per-connection basis (i.e. not an
         "all-or-none" approach). For example, it is possible to
         define a rule which requires a user to use SecurID and
         password authentication when establishing a TELNET
         connection from the public network. A second rule, however,
         may require the user to enter only a password when
         transferring files in either direction using FTP. Support
         for multiple authentication types is provided for TELNET and
         FTP.

         4.14 Trusted User

         Some sites are interested authenticating only those users
         establishing connections from the unprotected network. To
         that end, a concept of a trusted internal user has been
         incorporated into the InterLock. Although this is not a
         recommended configuration, it is possible to define rules in
         the ACRB which allow internal users to establish TELNET and
         FTP connections through the InterLock without an
         intermediate authentication step. When defining rules, the
         administrator specifies "trust" where a username would
         normally be entered. Using this model, it is possible to
         trust users from selected hosts or subnets while still
         requiring authentication information from all other users.

         It is important to note, that this TRUSTED feature is ONLY
         available to internal users attempting to connect to hosts
         on the public network. There is no corresponding concept of
         a trusted external user. For TELNET connections, the user
         would still initiate a connection to the InterLock. However,
         instead of being prompted for username and password, he/she
         would immediately receive the destination prompt. FTP users
         would also connect to the InterLock. At the ftp login
         prompt, the user would specify the remote username followed
         by the destination host (e.g. anonymous@ftp.ans.net). When
         the user is prompted for password, he/she would enter the
         password for the remote user (i.e. anonymous on the host
         ftp.ans.net) not the user's InterLock password.

         4.15 Encryption

         The InterLock can be configured with optional DES encryption
         daemons. These daemons support hardware and/or software DES
         encryption between InterLocks. It was implemented to allow
         those sites with multiple IP networks (each protected by an
         InterLock) to encrypt data as it passes over any public IP
         networks between InterLocks. The InterLock Encryption
         Service has been fully integrated with the ACRB. In
         addition to user id, private/public network or host address,
         and other rulebase parameters, the administrator can also
         specify the type of encryption (both, hardware, software,
         none) required for a particular connection request.
         Simultaneous encrypted and unencrypted sessions are
         supported under this model. Since the use of encryption can
         be specified in the ACRB, administrators have granular
         control over when it is required. For example, an
         administrator can define rules which require that hardware
         encryption be used when transferring files (FTP) and
         TELNETing between 2 InterLock-protected branches of the
         company during normal working hours (8:30-5:00). At all
         other times, no communications access will be permitted.
         Another rule could specify that no encryption should be used
         when connecting to a public FTP site. This combination of
         rules results in simultaneous encrypted FTP transfers to
         another InterLock-protected site and unencrypted FTP to a
         publicly accessible host. The use of encryption can be
         specified on a per-user basis. The use of RSA4 technology
         within the automated key management system will be available
         in a future release.

     4. RSA is a registered trademark of RSA Technologies, Inc. All
     Rights Reserved.

         4.16 General Packet Daemon (gpd)

         The general packet daemon (gpd) is a utility to support
         applications for which the InterLock does not provide a
         specific application-layer gateway. The application should
         be TCP-based (not UDP). The gpd is supported within the
         ACRB. However, because no login is associated with its use,
         there can be no user-level rules. Instead, rules can limit
         access based on all non-user criteria (source/destination
         address, time of day, day of the week, direction of
         connection, encryption required, etc.)

         The gpd provides a many-to-one mapping for a particular
         service. The following example describes how gpd would be
         configured for a customer that has developed a client-server
         application running on TCP port 72. This customer would
         like to allow external users to connect to an internal host
         and run the application. An InterLock gpd (NOTE: there can
         be multiple gpds running on an InterLock) needs to be
         configured to provide the gateway service. Gpd takes 2
         parameters, the TCP port and the IP address of the server
         (e.g. gpd 72 192.5.220.1). Users on the public network
         should be instructed to connect to port 72 on the InterLock.
         Gpd will perform all standard checks against the rulebase
         and, if authorized, will establish a second connection from
         the InterLock to port 72 on the internal host. Now traffic
         on port 72 of the InterLock will be read in on the public
         interface and copied out onto the private interface to the
         protected host (and vice-versa). Multiple clients can be
         simultaneously connected to one internal server.

         5. Service Model

         The InterLock is offered as a turn key service from ANS
         CO+RE Systems, Inc. The InterLock service is leased on an
         annual basis. The system is configured by ANS and shipped
         to the customer site ready for immediate operation. All
         hardware maintenance is provided by IBM.


         As part of the lease agreement, support is provided 24 hours
         a day, 365 days a year. The customer uses ANS as a
         single-point-of-contact for all software and hardware
         trouble requests. InterLock support staff will coordinate
         with IBM for any hardware maintenance. ANS maintains a
         dedicated InterLock support staff responsible for answering
         technical questions, coordinating new installations, and
         performing routine system maintenance and upgrades.

         6. Overview of ANS CO+RE Systems

         ANS CO+RE Systems, Inc., a wholly owned subsidiary of
         Advanced Network & Services, Inc. (ANS), is one of an
         exciting new breed of network service providers, leading the
         revolution in TCP/IP-based enterprise networking.

         ANS CO+RE operates a nation-wide data network in the United
         States called ANSnet, which also provides for direct
         international connectivity, and is the highest speed data
         network in the world. ANSnet is a central component of the
         worldwide Internet providing complete access to the enormous
         wealth of information available through the Internet.

         Attachments and attachment services to ANSnet are available
         at various access speeds, from 1,200/14,400 bps dial-up
         access up through full 45 Mbps (T3) access. ANS CO+RE is
         differentiated by its high-speed backbone bandwidth, which
         allows higher individual throughput and larger aggregated
         traffic than other networks, and by its high quality of
         service. Recently, ANS CO+RE was recognized by Network
         World as a premier wide-area network provider (July 19, 1993
         issue, p. 31-37).
          

         ANS CO+RE also provides highly qualified consulting for
         network design and implementation. ANS CO+RE's world class
         network operations center (NOC) in Ann Arbor, MI, provides
         full 7 by 24 management, monitoring and customer support.
         Customers can outsource their network operations to the ANS
         CO+RE NOC. While ANSnet is based on advanced TCP/IP
         technology, other protocols are supported via methods such
         as native switching and protocol "tunneling."

         ANSnet, with its high-speed backbone and high quality
         service, is at the forefront of a new enterprise networking
         revolution, leading the way with new products and services,
         taking advantage of emerging technologies to deliver new
         capabilities to customers at affordable prices.

         Advanced Network & Services, Inc. (ANS) is a not-for-profit
         company that manages the National Science Foundation's
         national high-speed data network, called NSFnet, under
         contract with MERIT, a consortium of nine Michigan
         universities.

         For general information on the InterLock family of services
         and on other ANS CO+RE services, call:

                 Client Services: (800) 456-8267

                 or write:

                 ANS CO+RE Systems, Inc.
                 100 Clearbrook Road
                 Elmsford, New York 10523

                 email: info@ans.net.

         Technical questions on the InterLock should be addressed to:

                 InterLock Customer Support Group
                 ANS CO+RE Systems, Inc.
                 1875 Campus Commons Drive, Suite 220
                 Reston, Virginia 22091-1552

                 (703) 758-8700

                 email: ilsupport@reston.ans.net

---------------------------------------------------
Eric Nowak, e-mail: nowak@ans.net
ANS CO+RE Systems, Inc. Phone: (703) 758-7705
1875 Campus Commons Dr. #220, Reston, VA 22091

----------
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3799(other)X
4026(without)X
720 2621(having)N
1010(to)X
1113(climb)X
1361(over)X
1560(security)X
1893(hurdles.)X
2252(Because)X
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2747(\256rst)X
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3430(of)X
3539(Bell)X
3729(Laboratories)X
4245(to)X
720 2733(install)N
11 s
986(UNIX)X
12 s
1236(were)X
1455(university)X
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2225(laboratories,)X
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3378(environment)X
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4224(no)X
720 2845(real)N
889(need)X
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1523(security)X
1852(was)X
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2220(until)X
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2648(time)X
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920 2985(In)N
1040(the)X
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1431(1980s,)X
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3101(their)X
11 s
3316(UNIX)X
12 s
3574(systems)X
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1067(laboratories)X
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1713(into)X
1889(the)X
2033(computer)X
2423(centers,)X
2746(allowing)X
3108(\(or)X
3245(forcing\))X
3580(the)X
3723(user)X
3908(population)X
720 3209(as)N
835(a)X
913(whole)X
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1293(use)X
1456(this)X
1630(new)X
1825(and)X
1999(wonderful)X
2429(system.)X
2779(Many)X
3038(businesses)X
3478(and)X
3653(government)X
4149(sites)X
720 3321(began)N
989(to)X
1103(install)X
11 s
1376(UNIX)X
12 s
1633(systems)X
1976(as)X
2094(well,)X
2322(particularly)X
2805(as)X
2923(desktop)X
3260(workstations)X
3789(became)X
4122(more)X
720 3433(powerful)N
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1269(affordable.)X
1745(Thus,)X
1993(the)X
11 s
2141(UNIX)X
12 s
2391(operating)X
2787(system)X
3086(is)X
3182(no)X
3310(longer)X
3588(being)X
3834(used)X
4042(only)X
4245(in)X
720 3545(environments)N
1271(where)X
1533(open)X
1747(collaboration)X
2283(is)X
2373(the)X
2517(goal.)X
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3750(students)X
4091(to)X
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720 3657(the)N
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1165(for)X
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3809(to)X
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720 3769(each)N
932(other.)X
1213(Businesses)X
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1832(their)X
11 s
2042(UNIX)X
12 s
2295(systems)X
2634(for)X
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893(payroll.)X
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11 s
2290(UNIX)X
12 s
2542(systems)X
2880(for)X
3026(various)X
3343(unclassi\256ed)X
3831(yet)X
3983(sensitive)X
720 3993(purposes.)N
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1058(complicate)X
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11 s
3170(UNIX)X
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3419(over)X
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1050(even)X
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1479(dif\256cult)X
1808(to)X
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2252(Perhaps)X
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2722(most)X
2933(problematic)X
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3747(are)X
3889(those)X
4116(relat-)X
720 4357(ing)N
870(to)X
972(networking:)X
1489(remote)X
1785(login,)X
2035(remote)X
2331(command)X
2739(execution,)X
3166(network)X
3509(\256le)X
3660(systems,)X
4016(diskless)X
720 4469(workstations,)N
1262(and)X
1428(electronic)X
1836(mail.)X
2083(All)X
2233(of)X
2339(these)X
2563(features)X
2894(have)X
3102(increased)X
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3636(utility)X
3893(and)X
4058(usabil-)X
720 4581(ity)N
856(of)X
11 s
968(UNIX)X
12 s
1220(by)X
1350(untold)X
1630(amounts.)X
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2680(same)X
2912(features,)X
3275(along)X
3523(with)X
3729(the)X
3882(widespread)X
720 4693(connection)N
1175(of)X
11 s
1285(UNIX)X
12 s
1535(systems)X
1871(to)X
1978(the)X
2128(Internet)X
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2859(networks,)X
3266(have)X
3479(opened)X
3788(up)X
3915(many)X
4160(new)X
720 4805(areas)N
942(of)X
1046(vulnerability)X
1563(to)X
1662(unauthorized)X
2189(abuse)X
2432(of)X
2536(the)X
2678(system.)X
10 s
10 f
576 5456(h)N
592(hhhhhhhhhhhhhh)X
9 s
1 f
576 5552(UNIX)N
10 s
776(is)X
849(a)X
905(registered)X
1242(trademark)X
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9 s
1673(AT&T)X
10 s
(.)S
9 s
1925(VAX)X
10 s
2101(is)X
2174(a)X
2230(trademark)X
2576(of)X
2663(Digital)X
2905(Equipment)X
3276(Corporation.)X
3723(Sun-3)X
3934(and)X
9 s
4068(NFS)X
10 s
4221(are)X
576 5648(trademarks)N
953(of)X
1040(Sun)X
1184(Microsystems.)X
1693(Annex)X
1927(is)X
2000(a)X
2056(trademark)X
2402(of)X
2489(Xylogics,)X
2818(Inc.)X
6 f
12 s
2421 6016(1)N

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%%Page: 2 3
12 s 0 xH 0 xS 6 f
14 s
576 832(1.2)N
824(THE)X
1078(INTERNET)X
1667(W)X
1773(ORM)X
1 f
12 s
920 1028(On)N
1069(the)X
1220(evening)X
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2110(2,)X
2215(1988,)X
2464(a)X
2540(self-replicating)X
3157(program,)X
3540(called)X
3804(a)X
2 f
3880(worm)X
1 f
4114(,)X
4171(was)X
720 1140(released)N
1064(on)X
1188(the)X
1334(Internet)X
1662([Seel88,)X
2008(Spaf88,)X
2332(Eich89].)X
2713(Overnight,)X
3155(this)X
3322(program)X
3676(had)X
3843(copied)X
4127(itself)X
720 1252(from)N
940(machine)X
1300(to)X
1409(machine,)X
1794(causing)X
2122(the)X
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2672(it)X
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3105(to)X
3214(labor)X
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3699(huge)X
3920(loads,)X
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720 1364(denying)N
1069(service)X
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1652(users)X
1888(of)X
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2697(Although)X
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3618(only)X
3827(infected)X
4176(two)X
720 1476(types)N
954(of)X
1065(computers,*)X
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1655(spread)X
1938(quickly,)X
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3667(sometimes)X
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720 1588(of)N
828(system)X
1123(administrators)X
1702(whose)X
1975(machines)X
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2969(While)X
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3475(system)X
3769(administrators)X
720 1700(were)N
933(aware)X
1189(that)X
1360(something)X
1787(like)X
1958(this)X
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2363 0.2604(theoretically)AX
2872(happen)X
9 f
3176(-)X
1 f
3255(the)X
3399(security)X
3731(holes)X
3961(exploited)X
720 1812(by)N
845(the)X
992(worm)X
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1461(well)X
1656(known)X
9 f
1946(-)X
1 f
2028(the)X
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2677(worm's)X
2998(break-ins)X
3384(came)X
3616(as)X
3724(a)X
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4016(surprise)X
720 1924(to)N
819(most)X
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920 2064(The)N
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1372(itself)X
1604(did)X
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2653(steal)X
2870(any)X
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3544(\(other)X
3814(than)X
4020(account)X
720 2176(passwords\),)N
1204(intercept)X
1571(private)X
1868(mail,)X
2093(or)X
2202(plant)X
2424(other)X
2650(destructive)X
3101(software)X
3460([Seel88].)X
3862(However,)X
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720 2288(did)N
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1193(to)X
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11 s
720 2400(MIT)N
12 s
881(,)X
11 s
938(NASA)X
12 s
1176('s)X
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2393(Goddard)X
2764(Space)X
3029(Flight)X
3294(Center,)X
3610(the)X
3763(Jet)X
3904(Propulsion)X
720 2512(Laboratory,)N
1215(and)X
1398(the)X
1560(U.)X
1697(S.)X
1818(Army)X
2086(Ballistic)X
2452(Research)X
2849(Laboratory,)X
3345(disconnected)X
3892(themselves)X
720 2624(from)N
959(the)X
1129(Internet)X
1481(to)X
1608(avoid)X
1874 0.2083(recontamination.)AX
2601(In)X
2733(addition,)X
3125(the)X
3295(Defense)X
3662(Communications)X
720 2736(Agency)N
1053(ordered)X
1381(the)X
1533(connections)X
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2383(the)X
11 s
2534(MILNET)X
12 s
2901(and)X
11 s
3073(ARPANET)X
12 s
3513(shut)X
3708(down,)X
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720 2848(them)N
952(down)X
1204(for)X
1355(nearly)X
1635(24)X
1770(hours)X
2022([Eich89,)X
2390(Elme88].)X
2809(Ironically,)X
3247(this)X
3425(was)X
3613(perhaps)X
3951(the)X
4107(worst)X
720 2960(thing)N
965(to)X
1087(do,)X
1254(since)X
1499(the)X
1664(\256rst)X
1860(\256xes)X
2088(to)X
2210(combat)X
2541(the)X
2706(worm)X
2978(were)X
3213(distributed)X
3673(via)X
3839(the)X
4005(network)X
720 3072([Eich89].)N
920 3212(This)N
1123(incident)X
1466(was)X
1647(perhaps)X
1978(the)X
2128(most)X
2347(widely)X
2641(described)X
3042(computer)X
3438(security)X
3776(problem)X
4130(ever.)X
720 3324(The)N
896(worm)X
1146(was)X
1321(covered)X
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1751(many)X
1990(newspapers)X
2463(and)X
2627(magazines)X
3059(around)X
3351(the)X
3494(country)X
3813(including)X
4202(the)X
2 f
720 3436(New)N
920(York)X
1130(Times)X
1 f
1375(,)X
2 f
1428(Wall)X
1639(Street)X
1893(Journal)X
1 f
2208(,)X
2 f
2261(Time)X
1 f
2498(and)X
2666(most)X
2883(computer-oriented)X
3625(technical)X
4004(publica-)X
720 3548(tions,)N
977(as)X
1103(well)X
1315(as)X
1441(on)X
1583(all)X
1726(three)X
1965(major)X
2236(television)X
2657(networks,)X
3079(the)X
3243(Cable)X
3513(News)X
3776(Network,)X
4181(and)X
720 3660(National)N
1087(Public)X
1368(Radio.)X
1681(In)X
1797(January)X
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2384(a)X
2463(United)X
2761(States)X
3027(District)X
3352(Court)X
3607(jury)X
3798(found)X
4058(Robert)X
720 3772(Tappan)N
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1354(the)X
1502(author)X
1778(of)X
1888(the)X
2036(worm,)X
2313(guilty)X
2567(of)X
2676(charges)X
2999(brought)X
3327(against)X
3629(him)X
3808(under)X
4056(a)X
4128(1986)X
720 3884(federal)N
1012(computer)X
1400(fraud)X
1627(and)X
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2033(law.)X
2244(Morris)X
2529(faces)X
2751(up)X
2871(to)X
2970(\256ve)X
3138(years)X
3365(in)X
3464(prison)X
3728(and)X
3892(a)X
3960($250,000)X
720 3996(\256ne)N
888([Schu90].)X
1312(Sentencing)X
1764(is)X
1852(scheduled)X
2261(for)X
2397(May)X
2597(4,)X
2693(1990.)X
6 f
14 s
576 4345(1.3)N
824(SPIES)X
1182(AND)X
1456(ESPIONAGE)X
1 f
12 s
920 4541(In)N
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1329(1986,)X
1571(the)X
1716(Lawrence)X
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2498(Laboratory,)X
2977(an)X
3095(unclassi\256ed)X
3576(research)X
3924(laboratory)X
720 4653(at)N
838(the)X
1004(University)X
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1586(California)X
2024(at)X
2141(Berkeley,)X
2560(was)X
2756(attacked)X
3125(by)X
3268(an)X
3406(unauthorized)X
3956(computer)X
720 4765(intruder)N
1059([Stol88,)X
1400(Stol89].)X
1765(Instead)X
2077(of)X
2191(immediately)X
2708(closing)X
3020(the)X
3173(holes)X
3411(the)X
3564(intruder)X
3904(was)X
4088(using,)X
720 4877(the)N
882(system)X
1193(administrator,)X
1775(Clifford)X
2129(Stoll,)X
2379(elected)X
2697(to)X
2815(watch)X
3088(the)X
3249(intruder)X
3597(and)X
3779(document)X
4202(the)X
720 4989(weaknesses)N
1202(he)X
1327(exploited.)X
1768(Over)X
1994(the)X
2146(next)X
2346(10)X
2476(months,)X
2817(Stoll)X
3034(watched)X
3390(the)X
3543(intruder)X
3883(attack)X
4149(over)X
720 5101(400)N
901(computers)X
1339(around)X
1643(the)X
1798(world,)X
2083(and)X
2259(successfully)X
2766(enter)X
2996(about)X
3247(30.)X
3428(The)X
3615(computers)X
4053(broken)X
720 5213(into)N
894(were)X
1105(located)X
1408(at)X
1502(universities,)X
1994(military)X
2324(bases,)X
2580(and)X
2743(defense)X
3061(contractors)X
3513([Stol88].)X
10 s
10 f
576 5309(h)N
592(hhhhhhhhhhhhhh)X
1 f
656 5419(*)N
736(Sun-3)X
949(systems)X
1224(from)X
1402(Sun)X
1548(Microsystems)X
2019(and)X
9 s
2155(VAX)X
10 s
2333(systems)X
2608(from)X
2787(Digital)X
3032(Equipment)X
3406(Corp.,)X
3629(both)X
3794(running)X
4066(variants)X
576 5515(of)N
663(4.)X
2 f
(x)S
1 f
9 s
777(BSD)X
935(UNIX)X
10 s
1135(from)X
1311(the)X
1429(University)X
1787(of)X
1874(California)X
2219(at)X
2297(Berkeley.)X
6 f
12 s
2421 6016(2)N

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%%Page: 3 4
12 s 0 xH 0 xS 6 f
1 f
920 832(Unlike)N
1220(many)X
1472(intruders)X
1852(seen)X
2061(on)X
2195(the)X
2351(Internet,)X
2713(who)X
2916(typically)X
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3523(systems)X
3865(and)X
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720 944(around)N
1014(to)X
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2022(intruder)X
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2848(for)X
2986(something)X
3413(speci\256c.)X
3781(Files)X
3994(and)X
4159(data)X
720 1056(dealing)N
1035(with)X
1237(the)X
1386(Strategic)X
1761(Defense)X
2108(Initiative,)X
2513(the)X
2663(space)X
2909(shuttle,)X
3222(and)X
3393(other)X
3623(military)X
3961(topics)X
4223(all)X
720 1168(seemed)N
1040(to)X
1146(be)X
1268(of)X
1379(special)X
1677(interest.)X
2039(Although)X
2432(it)X
2516(is)X
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3131(the)X
3279(intruder)X
3614(would)X
3884(have)X
4096(found)X
720 1280(any)N
888(truly)X
1099(classi\256ed)X
1486(information)X
1970(\(the)X
2149(Internet)X
2478(is)X
2571(an)X
2691(unclassi\256ed)X
3174(network\),)X
3574(it)X
3657(was)X
3836(highly)X
4112(prob-)X
720 1392(able)N
905(that)X
1074(he)X
1189(could)X
1427(\256nd)X
1600(a)X
1667(wealth)X
1948(of)X
2052(sensitive)X
2413(material)X
2754([Stol88].)X
920 1532(After)N
1151(a)X
1222(year)X
1416(of)X
1524(tracking)X
1868(the)X
2014(intruder)X
2347(\(eventually)X
2809(involving)X
3206(the)X
11 s
3350(FBI)X
12 s
3487(,)X
11 s
3537(CIA)X
12 s
3688(,)X
3740(National)X
4101(Secu-)X
720 1644(rity)N
890(Agency,)X
1249(Air)X
1413(Force)X
1667(Intelligence,)X
2182(and)X
2356(authorities)X
2798(in)X
2908(West)X
3141(Germany\),)X
3590(\256ve)X
3769(men)X
3970(in)X
4080(Hann-)X
720 1756(over,)N
947(West)X
1177(Germany)X
1567(were)X
1786(arrested.)X
2172(In)X
2285(March)X
2569(1989,)X
2818(the)X
2969(\256ve)X
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3366(charged)X
3704(with)X
3908(espionage:)X
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1091(been)X
1306(selling)X
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1746(material)X
2095(they)X
2293(found)X
2549(during)X
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3041(exploits)X
3378(to)X
3485(the)X
11 s
3633(KGB)X
12 s
3818(.)X
3898(One)X
4090(of)X
4202(the)X
720 1980(men,)N
940(Karl)X
1141(Koch)X
1379(\(``Hagbard''\),)X
1956(was)X
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2591(burned)X
2888(to)X
2993(death)X
3233(in)X
3339(an)X
3461(isolated)X
3792(forest)X
4042(outside)X
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2310([Stol89].)X
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1082(Hess,)X
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3275(of)X
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3929(a)X
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6 f
14 s
576 2777(1.4)N
824(OTHER)X
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1 f
12 s
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720 3197(NASA)N
12 s
958('s)X
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1323(network)X
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11 s
2279(IBM)X
12 s
2482(``Christmas)X
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3289([Risk87],)X
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11 s
1607(MILNET)X
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1976(to)X
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3881([Risk88],)X
4277(a)X
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11 s
1609(DECNET)X
12 s
1996(networks)X
2388([Risk89a],)X
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3365(U.)X
3499(S.)X
3617(banking)X
3968(networks)X
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2705(trojan)X
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3231(affecting)X
3602(personal)X
3956(computer)X
720 3645(users.)N
6 f
14 s
576 3994(1.5)N
824(SECURITY)X
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1555(IMPORTANT)X
1 f
12 s
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11 s
3011(UNIX)X
12 s
3262(operating)X
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2848(version)X
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2 f
(x)S
1 f
3322(of)X
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3589(OS)X
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3701(,)X
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12 s
967(sold)X
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11 s
961(UNIX)X
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1224(systems.)X
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1992(than)X
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1859(you)X
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2618(system)X
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4053(system)X
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1100(and)X
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1496(it)X
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2261(the)X
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3337(penetrate.)X
10 s
10 f
576 5070(h)N
592(hhhhhhhhhhhhhh)X
1 f
656 5180(*)N
736(The)X
889(term)X
1064 0.3375(``hacker,'')AX
1435(as)X
1530(applied)X
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1885(computer)X
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3371(connotation:)X
3820(``a)X
3939(person)X
4182(who)X
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809(learning)X
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1218(details)X
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671(computers,)X
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2625(necessary'')X
3021([Stee88].)X
3362(Unfortunately,)X
3861(the)X
3988(media)X
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879(this)X
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2249(meaning.)X
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3015(to)X
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3221(true)X
3369(hackers,)X
3658(we)X
3775(will)X
3922(use)X
4052(the)X
4173(term)X
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942(throughout)X
1313(this)X
1448(document.)X
6 f
12 s
2421 6016(3)N

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2421 6016(4)N

5 p
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12 s 0 xH 0 xS 6 f
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18 s
2140 896(SEC)N
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(O)S
2196(VIN)X
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1171(system)X
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3380(system)X
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1017(with)X
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1678(unauthorized)X
2220(access,)X
2529(either)X
2788(by)X
2923(legitimate)X
3349(users)X
3585(or)X
3704(crackers,)X
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4202(the)X
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2824(UNIX)X
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3074(security)X
3411(tools)X
3630(provided)X
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1469(as)X
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1843(as)X
1947(possible.)X
6 f
14 s
576 2177(2.1)N
824(ACCOUNT)X
1415(SECURITY)X
1 f
12 s
920 2373(One)N
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2796(a)X
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3248(by)X
3370(breaking)X
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3909(someone's)X
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1984(do,)X
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2594(systems)X
2924(have)X
3132(old)X
3281(accounts)X
3644(whose)X
3915(users)X
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901(the)X
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2020(with)X
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3488(so)X
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14 s
576 3058(2.1.1)N
917(Passwords)X
1 f
12 s
920 3254(The)N
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2654(account)X
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3361(If)X
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3994(discover)X
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3616(the)X
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2604(super-user,)X
3053(the)X
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3973(choosing)X
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2 f
12 s
1342(passwd)X
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1668(program)X
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2565(uppercase)X
2979(letter)X
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3311(are)X
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2937(the)X
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3905(the)X
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3844(three)X
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1750(-)X
1 f
1844(the)X
2003(login)X
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3803(the)X
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720 5214(catenated)N
1111(together)X
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1453(-)X
1 f
1532(a)X
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1918(by)X
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3818(\256rst)X
4007(and)X
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6 f
2421 6016(5)N

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720 832(names,)N
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576 1293(2.1.1.1)N
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12 s
920 1489(The)N
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1269(use)X
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1 f
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576 5086(2.1.1.3)N
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6 f
2421 6016(7)N

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2580(your)X
2791(own)X
2991(cracking)X
3358(program,)X
3743(and)X
3917(tailor)X
4156(it)X
4245(to)X
720 1756(your)N
920(own)X
1109(site.)X
1315(For)X
1472(a)X
1539(list)X
1681(of)X
1785(things)X
2044(to)X
2143(check)X
2392(for,)X
2552(see)X
2699(the)X
2841(list)X
2983(of)X
3087(guidelines)X
3507(above.)X
6 f
14 s
576 2105(2.1.2)N
917(Expiration)X
1494(Dates)X
1 f
12 s
920 2301(Many)N
1175(sites,)X
1402(particularly)X
1879(those)X
2114(with)X
2317(a)X
2392(large)X
2617(number)X
2943(of)X
3055(users,)X
3308(typically)X
3678(have)X
3892(several)X
4197(old)X
720 2413(accounts)N
1088(lying)X
1316(around)X
1613(whose)X
1888(owners)X
2195(have)X
2407(since)X
2635(left)X
2794(the)X
2942(organization.)X
3502(These)X
3762(accounts)X
4129(are)X
4277(a)X
720 2525(major)N
990(security)X
1340(hole:)X
1602(not)X
1770(only)X
1986(can)X
2165(they)X
2376(be)X
2512(broken)X
2824(into)X
3019(if)X
3124(the)X
3288(password)X
3696(is)X
3806(insecure,)X
4197(but)X
720 2637(because)N
1049(nobody)X
1361(is)X
1449(using)X
1681(the)X
1823(account)X
2147(anymore,)X
2532(it)X
2610(is)X
2698(unlikely)X
3038(that)X
3207(a)X
3274(break-in)X
3619(will)X
3793(be)X
3908(noticed.)X
920 2777(The)N
1099(simplest)X
1449(way)X
1638(to)X
1742(prevent)X
2060(unused)X
2361(accounts)X
2727(from)X
2943(accumulating)X
3493(is)X
3587(to)X
3692(place)X
3926(an)X
4047(expira-)X
720 2889(tion)N
900(date)X
1091(on)X
1217(every)X
1461(account.)X
1839(These)X
2099(expiration)X
2520(dates)X
2748(should)X
3034(be)X
3155(near)X
3351(enough)X
3664(in)X
3769(the)X
3916(future)X
4175(that)X
720 3001(old)N
872(accounts)X
1238(will)X
1418(be)X
1539(deleted)X
1848(in)X
1953(a)X
2026(timely)X
2303(manner,)X
2646(yet)X
2794(far)X
2931(enough)X
3244(apart)X
3467(that)X
3642(the)X
3790(users)X
4017(will)X
4197(not)X
720 3113(become)N
1048(annoyed.)X
1450(A)X
1547(good)X
1767(\256gure)X
2019(is)X
2110(usually)X
2415(one)X
2581(year)X
2774(from)X
2988(the)X
3133(date)X
3321(the)X
3466(account)X
3793(was)X
3969(installed.)X
720 3225(This)N
922(tends)X
1156(to)X
1262(spread)X
1544(the)X
1693(expirations)X
2152(out)X
2306(over)X
2508(the)X
2657(year,)X
2879(rather)X
3136(than)X
3334(clustering)X
3746(them)X
3971(all)X
4100(at)X
4202(the)X
720 3337(beginning)N
1138(or)X
1251(end.)X
1471(The)X
1654(expiration)X
2078(date)X
2272(can)X
2439(easily)X
2697(be)X
2821(stored)X
3089(in)X
3197(the)X
3348(password)X
3742(\256le)X
3897(\(in)X
4036(the)X
4186(full)X
720 3449(name)N
962(\256eld\).)X
1246(A)X
1348(simple)X
1638(shell)X
1853(script)X
2100(can)X
2267(be)X
2391(used)X
2600(to)X
2708(periodically)X
3202(check)X
3460(that)X
3638(all)X
3768(accounts)X
4138(have)X
720 3561(expiration)N
1135(dates,)X
1381(and)X
1544(that)X
1713(none)X
1924(of)X
2028(the)X
2170(dates)X
2392(has)X
2544(passed.)X
920 3701(On)N
1061(the)X
1203(\256rst)X
1376(day)X
1540(of)X
1645(each)X
1847(month,)X
2142(any)X
2306(user)X
2491(whose)X
2761(account)X
3086(has)X
3239(expired)X
3553(should)X
3834(be)X
3950(contacted)X
720 3813(to)N
824(be)X
944(sure)X
1133(he)X
1252(is)X
1344(still)X
1517(employed)X
1925(by)X
2049(the)X
2195(organization,)X
2729(and)X
2896(that)X
3069(he)X
3188(is)X
3280(actively)X
3614(using)X
3850(the)X
3996(account.)X
720 3925(Any)N
925(user)X
1125(who)X
1330(cannot)X
1627(be)X
1758(contacted,)X
2192(or)X
2312(who)X
2517(has)X
2685(not)X
2848(used)X
3064(his)X
3216(account)X
3556(recently,)X
3932(should)X
4229(be)X
720 4037(deleted)N
1025(from)X
1238(the)X
1382(system.)X
1723(If)X
1812(a)X
1880(user)X
2065(is)X
2154(unavailable)X
2624(for)X
2761(some)X
2989(reason)X
3265(\(e.g.,)X
3485(on)X
3606(vacation\))X
3990(and)X
4154(can-)X
720 4149(not)N
871(be)X
990(contacted,)X
1413(his)X
1554(account)X
1883(should)X
2168(be)X
2288(disabled)X
2638(by)X
2763(replacing)X
3151(the)X
3298(encrypted)X
3707(password)X
4098(in)X
4202(the)X
720 4261(password)N
1115(\256le)X
1271(entry)X
1502(with)X
1706(an)X
1830(asterisk)X
2157(\(*\).)X
2350(This)X
2554(makes)X
2833(it)X
2920(impossible)X
3370(to)X
3477(log)X
3632(in)X
3739(to)X
3846(the)X
3996(account,)X
720 4373(yet)N
862(leaves)X
1127(the)X
1269(account)X
1593(available)X
1966(to)X
2065(be)X
2180(re-enabled)X
2611(on)X
2731(the)X
2873(user's)X
3126(return.)X
6 f
14 s
576 4722(2.1.3)N
917(Guest)X
1265(Accounts)X
1 f
12 s
920 4918(Guest)N
1177(accounts)X
1547(present)X
1858(still)X
2036(another)X
2358(security)X
2696(hole.)X
2943(By)X
3089(their)X
3300(nature,)X
3599(these)X
3831(accounts)X
4202(are)X
720 5030(rarely)N
975(used,)X
1205(and)X
1374(are)X
1522(always)X
1819(used)X
2025(by)X
2150(people)X
2436(who)X
2630(should)X
2915(only)X
3115(have)X
3326(access)X
3601(to)X
3705(the)X
3852(machine)X
4208(for)X
720 5142(the)N
865(short)X
1084(period)X
1357(of)X
1464(time)X
1663(they)X
1856(are)X
2001(guests.)X
2316(The)X
2493(most)X
2707(secure)X
2981(way)X
3169(to)X
3272(handle)X
3557(guest)X
3788(accounts)X
4153(is)X
4245(to)X
720 5254(install)N
986(them)X
1209(on)X
1335(an)X
1456(as-needed)X
1871(basis,)X
2117(and)X
2286(delete)X
2547(them)X
2770(as)X
2880(soon)X
3091(as)X
3200(the)X
3347(people)X
3633(using)X
3870(them)X
4092(leave.)X
720 5366(Guest)N
975(accounts)X
1343(should)X
1630(never)X
1875(be)X
1997(given)X
2242(simple)X
2530(passwords)X
2960(such)X
3167(as)X
3278(``guest'')X
3640(or)X
3751(``visitor,'')X
4181(and)X
720 5478(should)N
1000(never)X
1238(be)X
1353(allowed)X
1682(to)X
1781(remain)X
2073(in)X
2172(the)X
2314(password)X
2700(\256le)X
2847(when)X
3079(they)X
3269(are)X
3411(not)X
3558(being)X
3796(used.)X
6 f
2421 6016(8)N

9 p
%%Page: 9 10
12 s 0 xH 0 xS 6 f
14 s
576 832(2.1.4)N
917(Accounts)X
1457(W)X
1563(ithout)X
1905(Passwords)X
1 f
12 s
920 1028(Some)N
1166(sites)X
1364(have)X
1574(installed)X
1929(accounts)X
2294(with)X
2493(names)X
2767(such)X
2971(as)X
3079(``who,'')X
3424(``date,'')X
3765(``lpq,'')X
4068(and)X
4235(so)X
720 1140(on)N
853(that)X
1034(execute)X
1365(simple)X
1658(commands.)X
2159(These)X
2425(accounts)X
2798(are)X
2952(intended)X
3320(to)X
3431(allow)X
3681(users)X
3914(to)X
4025(execute)X
720 1252(these)N
946(commands)X
1392(without)X
1715(having)X
2006(to)X
2110(log)X
2262(in)X
2366(to)X
2470(the)X
2617(machine.)X
3021(Typically)X
3420(these)X
3647(accounts)X
4013(have)X
4224(no)X
720 1364(password)N
1113(associated)X
1540(with)X
1742(them,)X
1990(and)X
2160(can)X
2324(thus)X
2514(be)X
2635(used)X
2841(by)X
2967(anyone.)X
3323(Many)X
3577(of)X
3687(the)X
3835(accounts)X
4202(are)X
720 1476(given)N
958(a)X
1025(user)X
1209(id)X
1308(of)X
1412(zero,)X
1626(so)X
1735(that)X
1904(they)X
2094(execute)X
2413(with)X
2608(super-user)X
3032(permissions.)X
920 1616(The)N
1095(problem)X
1441(with)X
1637(these)X
1861(accounts)X
2224(is)X
2314(that)X
2485(they)X
2677(open)X
2890(potential)X
3254(security)X
3585(holes.)X
3862(By)X
4000(not)X
4149(hav-)X
720 1728(ing)N
884(passwords)X
1324(on)X
1460(them,)X
1717(and)X
1896(by)X
2032(having)X
2334(super-user)X
2774(permissions,)X
3297(these)X
3535(accounts)X
3912(practically)X
720 1840(invite)N
964(crackers)X
1309(to)X
1408(try)X
1539(to)X
1638(penetrate)X
2016(them.)X
2281(Usually,)X
2629(if)X
2713(the)X
2856(cracker)X
3165(can)X
3324(gain)X
3515(access)X
3786(to)X
3886(the)X
4029(system,)X
720 1952(penetrating)N
1180(these)X
1404(accounts)X
1767(is)X
1857(simple,)X
2164(because)X
2494(each)X
2696(account)X
3021(executes)X
3378(a)X
3446(different)X
3803(command.)X
4256(If)X
720 2064(the)N
864(cracker)X
1174(can)X
1335(replace)X
1641(any)X
1807(one)X
1973(of)X
2080(these)X
2305(commands)X
2749(with)X
2947(one)X
3113(of)X
3220(his)X
3359(own,)X
3575(he)X
3693(can)X
3854(then)X
4047(use)X
4202(the)X
720 2176(unprotected)N
1199(account)X
1523(to)X
1622(execute)X
1941(his)X
2077(program)X
2427(with)X
2622(super-user)X
3046(permissions.)X
920 2316(Simply)N
1222(put,)X
1393(accounts)X
1754(without)X
2072(passwords)X
2495(should)X
2775(not)X
2922(be)X
3037(allowed)X
3366(on)X
3486(any)X
11 s
3647(UNIX)X
12 s
3889(system.)X
6 f
14 s
576 2665(2.1.5)N
917(Group)X
1283(Accounts)X
1823(and)X
2052(Groups)X
1 f
12 s
920 2861(Group)N
1192(accounts)X
1557(have)X
1767(become)X
2095(popular)X
2417(at)X
2515(many)X
2757(sites,)X
2980(but)X
3131(are)X
3277(actually)X
3611(a)X
3682(break-in)X
4031(waiting)X
720 2973(to)N
822(happen.)X
1175(A)X
1270(group)X
1520(account)X
1846(is)X
1936(a)X
2005(single)X
2261(account)X
2587(shared)X
2864(by)X
2986(several)X
3285(people,)X
3592(e.g.,)X
3781(by)X
3903(all)X
4026(the)X
4170(col-)X
720 3085(laborators)N
1134(on)X
1259(a)X
1332(project.)X
1678(As)X
1814(mentioned)X
2251(in)X
2356(the)X
2504(section)X
2807(on)X
2933(password)X
3325(security,)X
3684(users)X
3911(should)X
4197(not)X
720 3197(share)N
948(passwords)X
9 f
1372(-)X
1 f
1450(the)X
1593(group)X
1842(account)X
2167(concept)X
2492(directly)X
2812(violates)X
3136(this)X
3299(policy.)X
3612(The)X
3786(proper)X
4061(way)X
4245(to)X
720 3309(allow)N
963(users)X
1189(to)X
1293(share)X
1525(information,)X
2033(rather)X
2287(than)X
2482(giving)X
2757(them)X
2979(a)X
3051(group)X
3304(account)X
3633(to)X
3737(use,)X
3918(is)X
4011(to)X
4116(place)X
720 3421(these)N
951(users)X
1181(into)X
1364(a)X
1440(group.)X
1745(This)X
1949(is)X
2046(done)X
2266(by)X
2395(editing)X
2696(the)X
2846(group)X
3102(\256le,)X
2 f
3281(/etc/group)X
1 f
3725([Sun88a,)X
4101(1390;)X
720 3533(Sun88b,)N
1078(66],)X
1272(and)X
1453(creating)X
1806(a)X
1891(new)X
2093(group)X
2359(with)X
2572(the)X
2732(users)X
2971(who)X
3178(wish)X
3401(to)X
3518(collaborate)X
3989(listed)X
4240(as)X
720 3645(members.)N
920 3785(A)N
1013(line)X
1182(in)X
1281(the)X
1423(group)X
1671(\256le)X
1818(looks)X
2050(like)X
7 f
1008 3945 0.3830(groupname:password:groupid:user1,user2,user3,...)AN
1 f
720 4105(The)N
2 f
901(groupname)X
1 f
1386(is)X
1482(the)X
1632(name)X
1873(assigned)X
2236(to)X
2343(the)X
2493(group,)X
2773(much)X
3019(like)X
3196(a)X
3271(login)X
3501(name.)X
3790(It)X
3881(may)X
4079(be)X
4202(the)X
720 4217(same)N
947(as)X
1056(someone's)X
1496(login)X
1723(name,)X
1985(or)X
2093(different.)X
2501(The)X
2679(maximum)X
3098(length)X
3367(of)X
3475(a)X
3546(group)X
3798(name)X
4035(is)X
4127(eight)X
720 4329(characters.)N
1187(The)X
1365(password)X
1755(\256eld)X
1954(is)X
2046(unused)X
2346(in)X
11 s
2448(BSD)X
12 s
2619(-derived)X
2969(versions)X
3318(of)X
11 s
3425(UNIX)X
12 s
3643(,)X
3696(and)X
3864(should)X
4149(con-)X
720 4441(tain)N
915(an)X
1056(asterisk)X
1400(\(*\).)X
1609(The)X
2 f
1808(groupid)X
1 f
2177(is)X
2290(a)X
2382(number)X
2725(from)X
2961(0)X
3058(to)X
3182(65535)X
3471(inclusive.)X
3916(Generally,)X
720 4553(numbers)N
1100(below)X
1384(10)X
1529(are)X
1696(reserved)X
2071(for)X
2232(special)X
2549(purposes,)X
2963(but)X
3135(you)X
3328(may)X
3543(choose)X
3859(any)X
4048(unused)X
720 4665(number.)N
1091(The)X
1270(last)X
1432(\256eld)X
1631(is)X
1723(a)X
1794(comma-separated)X
2502(\(no)X
2658(spaces\))X
2969(list)X
3115(of)X
3223(the)X
3369(login)X
3595(names)X
3869(of)X
3977(the)X
4123(users)X
720 4777(in)N
819(the)X
961(group.)X
1257(If)X
1345(no)X
1465(login)X
1687(names)X
1957(are)X
2099(listed,)X
2357(then)X
2548(the)X
2691(group)X
2940(has)X
3093(no)X
3214(members.)X
3640(To)X
3772(create)X
4028(a)X
4096(group)X
720 4889(called)N
976(``hackers'')X
1422(with)X
1617(Huey,)X
1873(Duey,)X
2129(and)X
2292(Louie)X
2541(as)X
2645(members,)X
3046(you)X
3214(would)X
3478(add)X
3641(a)X
3708(line)X
3877(such)X
4077(as)X
4181(this)X
720 5001(to)N
819(the)X
961(group)X
1209(\256le:)X
7 f
1008 5161 0.3884(hackers:*:100:huey,duey,louie)AN
1 f
920 5349(After)N
1157(the)X
1309(group)X
1568(has)X
1731(been)X
1948(created,)X
2286(the)X
2439(\256les)X
2634(and)X
2808(directories)X
3250(the)X
3403(members)X
3791(wish)X
4007(to)X
4117(share)X
720 5461(can)N
884(then)X
1080(be)X
1201(changed)X
1552(so)X
1666(that)X
1840(they)X
2035(are)X
2182(owned)X
2467(by)X
2592(this)X
2760(group,)X
3037(and)X
3205(the)X
3352(group)X
3605(permission)X
4056(bits)X
4224(on)X
720 5573(the)N
865(\256les)X
1052(and)X
1218(directories)X
1652(can)X
1813(be)X
1931(set)X
2066(to)X
2169(allow)X
2411(sharing.)X
2770(Each)X
2991(user)X
3179(retains)X
3464(his)X
3604(own)X
3797(account,)X
4149(with)X
720 5685(his)N
856(own)X
1045(password,)X
1455(thus)X
1639(protecting)X
2054(the)X
2196(security)X
2525(of)X
2629(the)X
2771(system.)X
6 f
2421 6016(9)N

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12 s 0 xH 0 xS 6 f
1 f
920 832(For)N
1086(example,)X
1470(to)X
1578(change)X
1884(Huey's)X
2194(``programs'')X
2718(directory)X
3099(to)X
3207(be)X
3331(owned)X
3620(by)X
3750(the)X
3902(new)X
4096(group)X
720 944(and)N
900(properly)X
1267(set)X
1415(up)X
1552(the)X
1711(permissions)X
2210(so)X
2335(that)X
2520(all)X
2657(members)X
3050(of)X
3170(the)X
3328(group)X
3592(may)X
3798(access)X
4084(it,)X
4202(the)X
2 f
720 1056(chgrp)N
1 f
984(and)X
2 f
1147(chmod)X
1 f
1443(commands)X
1884(would)X
2148(be)X
2263(used)X
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1124(chgrp)X
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7 f
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1124(chmod)X
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14 s
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7 f
1008 2557 0.4219(+::0:0:::)AN
1 f
720 2717(and)N
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1008 2877(+:)N
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720 3037(These)N
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2120(in)X
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10 f
576 5298(h)N
592(hhhhhhhhhhhhhh)X
1 f
656 5408(*)N
736(Actually,)X
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2682(password)X
3008(\256le,)X
3153(regardless)X
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731(use.)X
6 f
12 s
2395 6016(10)N

11 p
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12 s 0 xH 0 xS 6 f
14 s
576 832(2.2)N
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12 s
920 1028(As)N
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11 s
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12 s
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14 s
576 2413(2.2.1)N
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12 s
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14 s
576 4330(2.2.1.1)N
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1936(\))X
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3294(\))X
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1835(,)X
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3442(hosts.equiv)X
1 f
3918(\256le,)X
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6 f
2395 6016(11)N

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3459(you)X
3636(should)X
3926(be)X
4051(sure)X
4245(to)X
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972(replace)X
1283(the)X
1433(Sun)X
1613(default)X
2 f
1912(hosts.equiv)X
1 f
2389(with)X
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4048(the)X
4197(\256le)X
720 1936(altogether.)N
5 f
14 s
576 2285(2.2.1.2)N
1010(The)X
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1600(File)X
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12 s
920 2481(The)N
2 f
1098(.rhosts)X
1 f
1400(\256le)X
1551([Sun88a,)X
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2994(and)X
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2 f
3698(hosts.equiv)X
1 f
4173(\256le,)X
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720 2705(eral.*)N
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1896(a)X
2 f
1976(.rhosts)X
1 f
2287(\256le)X
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3376(to)X
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720 2929(between)N
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1444(they)X
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3992(not)X
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720 3041(each)N
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1556(hosts.equiv.)X
1 f
2055(Unfortunately,)X
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720 3153(While)N
2 f
994(hosts.equiv)X
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1478(is)X
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720 3265(tively,)N
997(any)X
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1825(a)X
2 f
1901(.rhosts)X
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2208(\256le)X
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2184(.rhosts)X
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2485(\256les)X
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4020(the)X
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949(The)X
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1988(should)X
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2540(the)X
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2995(often)X
3228(for)X
3375(violations)X
3790(of)X
3905(this)X
4079(policy)X
720 3741(\(see)N
899(Section)X
1212(3.3.1.4\).)X
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2601(this)X
2764(rule)X
2938(is)X
3027(the)X
3170(``root'')X
3478(account;)X
3830(a)X
2 f
3898(.rhosts)X
1 f
4197(\256le)X
720 3853(may)N
910(be)X
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6 f
14 s
576 4202(2.2.2)N
917(Secure)X
1320(Term)X
1594(inals)X
1 f
12 s
920 4398(Under)N
1200(newer)X
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2171(,)X
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3256(a)X
3334(nonsecure)X
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1006(password.)X
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2 f
2892(su)X
1 f
3030(command)X
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720 4734(however.\))N
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1355(\256le)X
2 f
1515(/etc/ttytab)X
1 f
1955([Sun88a,)X
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3995(are)X
4149(con-)X
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1022(secure.\262)X
1388(A)X
1481(short)X
1697(excerpt)X
2005(from)X
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2379(\256le)X
2526(is)X
2614(shown)X
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10 s
10 f
576 5284(h)N
592(hhhhhhhhhhhhhh)X
1 f
656 5394(*)N
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2 f
1052(hosts.equiv)X
1 f
1443(may)X
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2512(combinations)X
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3228(but)X
3350(this)X
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3558(rarely)X
3766(done.)X
656 5504(\262)N
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1622(Berkeley)X
9 s
1930(UNIX)X
10 s
(,)S
2150(this)X
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2480(called)X
2 f
2692(/etc/ttys)X
1 f
2954(.)X
6 f
12 s
2395 6016(12)N

13 p
%%Page: 13 14
12 s 0 xH 0 xS 6 f
1 f
7 f
1008 880(console)N
1530 0.4018("/usr/etc/getty)AX
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3096(sun)X
3618(off)X
3850(secure)X
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2458 0.4219(std.9600")AX
3096(unknown)X
3618(off)X
3850(secure)X
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3096(unknown)X
3618(off)X
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3096(network)X
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3096(network)X
3618(off)X
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1530(none)X
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3618(off)X
3850(secure)X
1 f
720 1600(The)N
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7 f
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1124(kill)X
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1 f
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1242(init)X
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1411(process)X
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2229(ttytab)X
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2489(\256le.)X
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2284(ttytab)X
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2555(is)X
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720 2732(\256le)N
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3451(su)X
1 f
3594(command.)X
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4050(access.)X
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1003(how)X
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2268(should)X
2548(be)X
2663(set)X
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14 s
576 3781(2.2.3)N
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1842(System)X
1 f
12 s
920 3977(The)N
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11 s
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12 s
2172(\))X
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12 s
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3953(your)X
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11 s
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12 s
4020(Release)X
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12 s
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5 f
14 s
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1 f
12 s
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2 f
1250(/etc/exports)X
1 f
1745([Sun88a,)X
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6 f
2395 6016(13)N

14 p
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12 s 0 xH 0 xS 6 f
1 f
720 832(to)N
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2157(\256le)X
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1008 1104(/usr)N
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907(access=)X
1 f
1276(keyword)X
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1 f
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1380(exports)X
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3652(the)X
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7 f
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