CentOS – iptables Not Installed

centosfirewalliptables

If a machine does not have iptables installed, is there still a firewall running?

If yes, how to I disable / change rules?

if I enter the command iptables I receive the response:

iptables v1.4.7: no command specified

[root@ruad1 ~]# iptables -L
FATAL: Module ip_tables not found.
iptables v1.4.7: can't initialize iptables table `filter': Permission denied (you must be root)
Perhaps iptables or your kernel needs to be upgraded.

I have been searching but all documentation on firewalls for centos seems to refer to iptables.

If I do ip route list, there seems to be a lot of rules?

Edit: Answer to questions in comments:

output of ls -alL /sbin/iptables 

-rwxr-xr-x 1 root root 54200 Nov 23 2013 /sbin/iptables

I receive the following when I do iptables restart

iptables restart output

kernel version:

2.6.32-5-vserver-amd64

contents of /lib/modules/2.6.32-5-vserver-amd64

/lib/modules/2.6.32-5-vserver-amd64

Any command that I issue with iptables (restart, stop ..) all receive the same error as pasted above.

/sbin/iptables output:

iptables v1.4.7: can't initialize iptables table `filter': Permission denied (you must be root)

Perhaps iptables or your kernel needs to be upgraded.

output of touch /tmp/foo; ls -la /tmp/foo

-rw-r--r-- 1 root root 0 Jun 27 16:51 /tmp/foo

Best Answer

It looks like the machine is running in a virtualized environment, or more specific: in an operating system-level virtualized environment, like LXC, OpenVZ or Virtuozzo. The kernel version (2.6.32-5-vserver-amd64) gives this away.

In such an environment the kernel is shared between the host and the guest systems, and not all kernel APIs are available in VMs. I guess that's the reason why you have a permission error when calling iptables.

When you find out in which environment your machine is running, you might be able to find a solution online:

But you might have to contact the administrator of the host system to make the necessary changes.

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