How to view and edit the ephemeral port range on Linux?

Question

In my Linux system ephemeral port range is showing different ranges as follows

$ cat /proc/sys/net/ipv4/ip_local_port_range 
32768  61000



cat /etc/sysctl.conf | grep net.ipv4.ip_local_port_range
net.ipv4.ip_local_port_range = 9000 65500

Which will be the effective ephemeral port range in my system?

Only output of /proc files or sysctl tool will show the actual effective port range. /etc/sysctl.conf may or may not be loaded on boot. In your case it does not match so it is either not loaded or overwritten. /proc tells the truth (so should `sysctl net.ipv4.ip_local_port_range`) — eckes, Oct 16 '17 at 16:46

score 28 · Accepted Answer · edited Jan 09 '22 at 19:53

28

Following command will list the ephemeral port range in Linux system

sysctl net.ipv4.ip_local_port_range

If we don't want to reboot, after editing /etc/sysctl.conf file if we execute following command it will be effective.

sysctl -p /etc/sysctl.conf .

The truth of the matter of effective range is output of

sysctl net.ipv4.ip_local_port_range

as mentioned by eckes in comment.

edited Jan 09 '22 at 19:53

Huckle

answered Feb 18 '15 at 04:45

Steephen

For me on Red Hat Enterprise Linux Server release 7.6 (Maipo) the command sysctl doesn't exist. Is there an alternative? – junkie May 14 '21 at 14:14
@junkie Did you try as `sudo sysctl.... ` ? – Arnaud Bouchez Mar 07 '23 at 15:43

1 Answers1