Default iptables rules and Imunify360

Issue

Default iptables rules specified in the /etc/sysconfig/iptables file applied on the system before Imunify360 rules. This can cause the inaccessibility of ports allowed in Imunify360.

Environment

• Imunify360
• iptables
• Any supported panel
• Any supported OS

Solution

It is necessary to check if the server uses a separate service iptables.service, which takes data from the /etc/sysconfig/iptables file.

# systemctl status iptables
● iptables.service - IPv4 firewall with iptables
   Loaded: loaded (/usr/lib/systemd/system/iptables.service; enabled; vendor preset: disabled)
   Active: active (exited) since Thu 2022-02-10 16:26:01 -03; 17h ago
 Main PID: 780 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/iptables.service

Feb 10 16:25:58 srv22.wcorp22.com systemd[1]: Starting IPv4 firewall with iptables...
Feb 10 16:26:01 srv22.wcorp22.com iptables.init[780]: iptables: Applying firewall rules: [  OK  ]
Feb 10 16:26:01 srv22.wcorp22.com systemd[1]: Started IPv4 firewall with iptables.

If it is allowed, the set of rules in this file should be reset. Imunify360 needs to be stopped beforehand.

# cp /etc/sysconfig/iptables /root/iptables.backup

# systemctl stop imunify360

# iptables -P INPUT ACCEPT
# iptables -P OUTPUT ACCEPT
# iptables -F

# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables: [ OK ]

# systemctl start imunify360

Cause

A separate service applies rules when the server is started and this affects the handling of traffic in the iptables chains.

Useful links

• iptables(8) - Linux man page