Modify Linux kernel parameters to reduce the TIME-WAITsockets in TCP connections

Modify the Linux kernel parameters to reduce the TIME-WAITsockets-Linux Enterprise Application-Linux server application information in the TCP connection. For more information, see the following. Since the launch of a new set of Apache servers, I used the netstat-an command to find a large number of TCP connections in the TIME-WAIT Status on the server, so I used/sbin/sysctl-a to view Linux kernel parameters, read the relevant information, and decided to modify the two parameters, to reduce the TIME-WAIT sockets in TCP connections.

Vi/etc/sysctl. conf

Edit the/etc/sysctl. conf file and add three lines:
Net. ipv4.tcp _ syncookies = 1
Net. ipv4.tcp _ tw_reuse = 1
Net. ipv4.tcp _ tw_recycle = 1

Note:
Net. ipv4.tcp _ syncookies = 1 indicates enabling SYN Cookies. When a SYN wait queue overflows, cookies are enabled to prevent a small number of SYN attacks. The default value is 0, indicating that the process is disabled;

Net. ipv4.tcp _ tw_reuse = 1 indicates enabling reuse. Allow TIME-WAIT sockets to be re-used for a New TCP connection. The default value is 0, indicating that the TCP connection is disabled;

Net. ipv4.tcp _ tw_recycle = 1 indicates to enable quick recovery of TIME-WAIT sockets in TCP connections. The default value is 0, indicating to disable it.

Run the following command to make the modification take effect immediately:
/Sbin/sysctl-p

Use the following statement to check the TCP status of the server:
Netstat-n | awk '/^ tcp/{++ S [$ NF]} END {for (a in S) print a, S [a]}'

The returned results are as follows:
ESTABLISHED 1423
FIN_WAIT1 1
FIN_WAIT2 262
SYN_SENT 1
TIME_WAIT 962

Effect: the number of sockets in the TIME_WAIT status is reduced from more than 10000 to about 1000. Sockets in the SYN_RECV waiting for processing status is 0, and the original value is 50 ~ 300.