In Linux, the net.ipv4.ip_nonlocal_bind sysctl variable controls whether or not a process can bind to an IP address that does not exist on the local system. By default, this variable is set to 0, which means that a process cannot bind to an IP address that does not exist on the local system.
To allow a process to bind to an IP address that does not exist on the local system, you can set the net.ipv4.ip_nonlocal_bind sysctl variable to 1 by using the following command:
sudo sysctl -w net.ipv4.ip_nonlocal_bind=1
This will change the value of the sysctl variable temporarily, If you want to make this change permanent, you can edit the /etc/sysctl.conf file and add the following line:
net.ipv4.ip_nonlocal_bind=1
Then run the command sudo sysctl -p to reload the sysctl configuration.
It’s worth noting that allowing non-local binding can be a security risk, as it can allow an attacker to bind to an IP address that they should not have access to, and use it to launch attacks or intercept traffic. Therefore, it should be used with caution, and only in situations where it is necessary.