SUMMARY: SunOS 4.1.x: How can I change default tcp/ip params.? (tcp_keepalive)

From: Vitaly Beliaev (
Date: Tue Jan 13 1998 - 03:32:20 CST

Hello wizards!

Sorry for such long delay in writing the SUMMARY. The company I am
working at has been disconnected from provider for three weeks. So
I had to look through voluminous documentation and find appropriate

The only reply I have received was from Stefan Voss <>

He advised to look and edit file /sys/netinet/in_proto.c. There you find the
following parameters:

tcp_sendspace tcp_recvspace tcp_default_mss tcp_ttl

and some others. After modifying this file, you have to build a new kernel and reboot the machine. --

I manage Solbourne 700,900 servers running SunOS 4.1.2. And I found that TCP parameters have to be specified in /usr/kvm/sys/netinet/in_proto.c, so perhaps you will wish to make its original copy prior to editing one. The following TCP parameters could be set here:

tcp_keeplen (1) tcp_keepidle = 2-20 (14400 1/2sec) tcp_keepintvl = 2-20 (150 1/2sec) tcp_ttl = 30 (60 sec) tcp_sendspace = 65535 (4096*4) tcp_recvspace = 65535 (4096*4) tcp_default_mss = 2048 (512 bytes)

After building the kernel you can always see the values in running system.

Regards, Vitaly Beliaev

-=========================================================================- Vitaly Beliaev: Unix systems administrator JVSC MMK, RUSSIA e-mail: voice: +7 (3511) 335639

if vegetarian prefers vegetables, then what's the snack for humanitarian? -=========================================================================-

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