pitter patter on the keyboard

The firewall on a RHEL system is configured by default with system-config-firewall, which on the console is an annoying ncurses menu which doesn’t permit adding custom ports/protocols.

The ports you probably want open for Zimbra are:

25
    smtp [mta] - incoming mail to postfix 
80
    http [mailbox] - web mail client 
110
    pop3 [mailbox] 
143
    imap [mailbox] 
443
    https [mailbox] - web mail client over ssl 
465
    smtps [mta] - incoming mail to postfix over ssl (Outlook only) 
587
    smtp [mta] - Mail submission over tls 
993
    imaps [mailbox] - imap over ssl 
995
    pops [mailbox] - pop over ssl 
7071
    https [mailbox] - admin console

The raw iptables configuration is stored in /etc/sysconfig/iptables:

# cat /etc/sysconfig/iptables
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 110 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 143 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 456 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 587 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 993 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 995 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 7071 -j ACCEPT 
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

Ensure the iptables init script is part of your default runlevel.

# chkconfig --level 345 iptables on

Restart it to apply the changes.

/etc/init.d/iptables restart

NetworkManager is an annoying network configurator for home users. It will interfere with custom network-scripts unless disabled.

# chkconfig --level 2345 NetworkManager off
# /etc/init.d/NetworkManager stop

It’s important to know what version of RHEL/Fedora/CentOS/Scientific Linux/etc. you are dealing with when looking for version-compatible RPMs that are out-of-repo. I always end up forgetting how to do this, so for our mutual benefit:

$ cat /etc/redhat-release
CentOS release 5.6 (Final)