13. Better manage your TCP/IP resources

This hack just make the time default values for TCP/IP connection lower so that more connections can be handled by time on your TCP/IP protocol. The following will decrease the amount of time your Linux box will try take to finish closing a connection and the amount of time before it will kill a stale connection. This will also turn off some IP extensions that aren't needed. The default setup for the TCP/IP parameters we'll change under Red Hat Linux are:

To adjust the new TCP/IP values, type the following commands on your terminal:

             [root@deep] /#echo 30 >/proc/sys/net/ipv4/tcp_fin_timeout 
             [root@deep] /#echo 1800 >/proc/sys/net/ipv4/tcp_keepalive_time 
             [root@deep] /#echo 0  >/proc/sys/net/ipv4/tcp_window_scaling 
             [root@deep] /#echo 0  >/proc/sys/net/ipv4/tcp_sack 
             [root@deep] /#echo 0  >/proc/sys/net/ipv4/tcp_timestamps

Execute the above commands and put them in your /etc/rc.d/rc.local file so you don't need to type them again each time your system reboots.

Version 6.2 only

Edit the /etc/sysctl.conf file and add the following lines:

             # Decrease the time default value for tcp_fin_timeout connection
             net.ipv4.tcp_fin_timeout = 30
             # Decrease the time default value for tcp_keepalive_time connection
             net.ipv4.tcp_keepalive_time = 1800
             # Turn off the tcp_window_scaling
             net.ipv4.tcp_window_scaling = 0
             # Turn off the tcp_sack
             net.ipv4.tcp_sack = 0
             # Turn off the tcp_timestamps
             net.ipv4.tcp_timestamps = 0

You must restart your network for the change to take effect. The command to manually restart the network is the following:

             [root@deep] /# /etc/rc.d/init.d/network restart

             Setting network parameters     [  OK  ]
             Bringing up interface lo     [  OK  ]
             Bringing up interface eth0     [  OK  ]
             Bringing up interface eth1     [  OK  ]