Hello everyone,
This is a correction to my last summary. Thank you Jerry for pointing the error.
Correction: downing the interface before using ifconfig to change the netmask is NOT necessary.
Please read Jerry's response below for more detail.
Victor
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From: Jerry Springer[SMTP:springer@aitsun500.tcinc.com]
Here is the simple session I ran on my system running Sol. 2.5.
You can see my original ifconfig and netstat shows a netmask of
ffffffc0 and the appropriate routing destination of 165.137.208.128
listed in the netstat, the value of which is computed based on my
IP address and netmask.
Notice the output after the change of netmask.
The ifconfig -a shows the change and the netstat command shows that
the change is being used in the new computed destination value for the le0
interface.
What it will not change automatically is the broadcast address. Changing the
netmasks file and rebooting will automatically change the broadcast address
correctly. Downing the interface first, changing the netmask and then bringing
it up again might change the braodcast address automatically also. But you can
change it dynamically just as you changed the netmask. Downing the interface
is NOT A NECESSITY.
# ifconfig le0
le0: flags=863<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST> mtu 1500
inet 165.137.208.132 netmask ffffffc0 broadcast 165.137.208.191
ether 8:0:20:73:a1:dd
# netstat -rn
Routing Table:
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
127.0.0.1 127.0.0.1 UH 0 5541 lo0
165.137.208.128 165.137.208.132 U 3 2 le0
224.0.0.0 165.137.208.132 U 3 0 le0
default 165.137.208.190 UG 0 52020
# ifconfig le0 netmask 255.255.255.0
# ifconfig le0
le0: flags=863<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST> mtu 1500
inet 165.137.208.132 netmask ffffff00 broadcast 165.137.208.191
ether 8:0:20:73:a1:dd
# netstat -rn
Routing Table:
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
127.0.0.1 127.0.0.1 UH 0 5541 lo0
165.137.208.0 165.137.208.132 U 3 4 le0
224.0.0.0 165.137.208.132 U 3 0 le0
default 165.137.208.190 UG 0 52018
#
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