Bug 147914 – Trying to tweak TCP settings but getting errors

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description Kim Nilsson 2006-09-17 04:55:11 UTC]

Following this guide: http://gentoo-wiki.com/HOWTO_TCP_Tuning

But I'm getting these errors.

error: "net.ipv4.tcp_syncookies" is an unknown key
(This isn't in the guide, but as I was working with this I came across a link about syn_cookies being disabled default.) It seems this value is wrong.

These, however, are in the guide and are listed when I do a 'sysctl -a', though I can't seem to set them.

error: "Invalid argument" setting key "net.core.rmem_max"
error: "Invalid argument" setting key "net.core.wmem_max"
error: "Invalid argument" setting key "net.ipv4.tcp_rmem"
error: "Invalid argument" setting key "net.ipv4.tcp_wmem"

My current sysctc.conf looks like this (at the end, with the relevant changes).

net.core.rmem_max="16777216"
# This setting changes the maximum network receive buffer size to 16777216 bytes.

net.core.wmem_max="16777216"
# The same thing for the send buffer

net.ipv4.tcp_rmem="4096 87380 16777216"
# This sets the kernel's minimum, default, and maximum TCP receive buffer sizes. You might be surprised, seeing the maximum of 16M,
# that many Unix-like operating systems still have a maximum of 256K!

net.ipv4.tcp_wmem="4096 65536 16777216"
# A similar setting for the TCP send buffer. Note that the default value is a little lower. Don't worry about this,
# the send buffer size is less important than the receive buffer.

net.ipv4.tcp_no_metrics_save=1
# This removes an odd behavior in the 2.6 kernels, whereby the kernel stores the slow start threshold for a client between TCP sessions.
# This can cause undesired results, as a single period of congestion can affect many subsequent connections. I recommend that you disable it.

net.ipv4.ip_default_ttl = 73
# Many attackers use the TTL (time to live) as a parameter for profiling your operating system.

The last two settings work just fine.

[Comment 1 Jakub Moc (RETIRED) 2006-09-17 05:04:36 UTC]

This has nothing to do w/ security.

[Comment 2 Jakub Moc (RETIRED) 2006-09-17 05:05:36 UTC]

Gentoo does not maintain gentoo-wiki.com nor review its contents for accuracy. And Gentoo Bugzilla is not a support forum.