How to verify if iptables is running or the firewall is activated

When I run on my linux Redhat version 6.8 machine - service iptables status

I get the rules table ( but not if iptables running or not )

Does the following show that iptables is running?

 # service iptables status
 Table: filter
 Chain INPUT (policy ACCEPT)
 num  target     prot opt source               destination
 1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state   RELATED,ESTABLISHED
 2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0
 3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
 4    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state  NEW tcp dpt:22
 5    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject- with icmp-host-prohibited

 Chain FORWARD (policy ACCEPT)
 num  target     prot opt source               destination
 1    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject- with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination

Iptables is enabled on boot

# chkconfig --list iptables
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off

King David

Posted 2016-09-14T15:49:39.303

Reputation: 405

Answers

There is no such thing as "iptables is running" - there is no dedicated firewall process to monitor.

If the kernel modules are loaded and rules defined (both of which are proven by showing a valid rules table), the filtering is active. It is done in-kernel on events (packet rcv/snd) and not on a separate process.

So: Yes, if the rules shown are what you want, then your firewall is up.

Eugen Rieck

Posted 2016-09-14T15:49:39.303

Reputation: 15 128

6Not always true. Under CentOS7 you have firewalld installed by default, and you can check its status by running systemctl status firewalld. Also, a package called iptables-services can be installed and if started (service name: iptables), you can check if it's running or not. – nKn – 2016-09-14T16:07:06.943

3@nKn - the question was: how to verify if iptables is running. firewalld does NOT replace iptables, it's just used to configure it. A dead firewalld with active iptables rules mean, that the firewall is UP, not DOWN – Eugen Rieck – 2016-09-14T16:11:05.883

1Exactly, and I said it can be checked installing the iptables-services packages and checking systemctl status iptables, which will tell you if iptables is running or not. – nKn – 2016-09-14T16:14:39.837

And again, again, again: There is no such thing as "iptables is running". – Eugen Rieck – 2016-09-15T08:07:47.673

1@nKn Thanks bro. firewalld was my issue! – Habeeb Perwad – 2018-02-28T10:20:28.487

This way we can know only if its not running

[root@vm1 ~]# service iptables status iptables: Firewall is not running.

if running , it prints rules table as shown to you

programmer

Posted 2016-09-14T15:49:39.303

Reputation: 1