Linux Increase Local Port Range with net.ipv4.ip_local_port_range

If your Linux server is opening lots of outgoing network connection, you need to increase local port range. By default range is small. For example squid proxy server can come under fire if it runs out of ports.

You can use sysctl command to to modify kernel parameters at runtime. The parameters available are those listed under /proc/sys/. Please note that this hack is only useful for high bandwidth, busy Linux servers or large scale grid servers.

To find current range type

$ sysctl net.ipv4.ip_local_port_range
Output:

net.ipv4.ip_local_port_range = 32768    61000

Set new local port range

You can set the range with the following command:
# echo 1024 65535 > /proc/sys/net/ipv4/ip_local_port_range
OR
$ sudo sysctl -w net.ipv4.ip_local_port_range="1024 64000"

You may need to edit /etc/sysctl.conf file, to make changes to /proc filesystem permanently i.e. append the following to your /etc/sysctl.conf file:
# increase system IP port limits
net.ipv4.ip_local_port_range = 1024 65535

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