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Software Engineer

Steve WhiteLinux sockets in TIME_WAIT status

About Linux sockets in TIME_WAIT status

We recently came across an application used a significant number of open/close TCP connections under Redhat Enterprise Linux 5.4. As a result the system ran out of local ports to open new connections due a number of sockets that were stuck in TIME_WAIT status. Using the ‘netstat’ command from a shell we could see that it was this particular application causing the problem because the destination port numbers were all the same.

Sockets which are listed in CLOSE_WAIT status are different and many of these usually means that a particular application isn’t closing it’s socket file descriptors off correctly.

More about fixing Linux socket TIME_WAIT status

This problem was causing issues for all network related software on the system. To alleviate this problem we set the following kernel parameters as root and rebooted:

echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle
echo 1 > /proc/sys/net/ipv4/tcp_tw_reuse
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout

After this change the number of sockets in TIME_WAIT state were drastically reduced, problem solved!

Regards,

Steve

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