Enable Promiscous mode in CentOS 7

Question

How to enable promiscuous mode on network adapter. I have tried by adding PROMISC=yes in /etc/sysconfig/network-scripts/ifcfg-ensxxx but no effect even after network restart or rebooting the system.

Solution

CentOS 7 /usr/share/doc/initscripts-9.49.24/sysconfig.txt says:

 No longer supported:
 PROMISC=yes|no (enable or disable promiscuous mode)
 ALLMULTI=yes|no (enable or disable all-multicast mode)

So for enabling you have to run:

ip link set ethX promisc on

Or if you want to happen on boot you can use systemd service rc-local.
Put the above line in /etc/rc.d/rc.local (don't forget to change ethX with your proper device), then:

chmod u+x /etc/rc.d/rc.local
systemctl enable rc-local
systemctl start rc-local

Comments

[taliezin]

@AxelBeckert, I really don't know why.