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Increase IP_local_port_range TCP port range

On Linux, there is a sysctl parameter called ip_local_port_range that defines the minimum and maximum port a networking connection can use as its source (local) port.


To find out the current IP range, use the following commands: (CentOS5/6)

$cat /proc/sys/net/ipv4/ip_local_port_range

32768 61000


The value is shown as “minimum maximum” value, so the local port for new connections will be between 32.768 and 61.000, by default that’s a 28.232 range of ports. Sounds plenty, but heavy traffic servers may reach this limit.


To increase port range, add following parameter to configuration file /etc/sysctl.conf

net.ipv4.ip_local_port_range = 30000 65535

And restart OS.

Generally, in many types of OSs, ephemeral ports are defined as under 65535, so we recommend to set the range under 65535.


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