#! /bin/sh
# /etc/iptables.bak
# Let's save typing & confusion with variables
IPTABLES=/sbin/iptables
# Flush active rules and custom tables
$IPTABLES --flush
$IPTABLES --delete-chain
# set the defaults so that by-default incoming packets are dropped, unless explicitly allowed;
# for a desktop workstation, we'll let lots of (unpredictable) outgoing packets go freely.
$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT ACCEPT
# INBOUND POLICY
# ==============
# of course, accepting loopback is a good idea
$IPTABLES -A INPUT -i lo -j ACCEPT
# (Applies to packets entering our network interface from the network,
# and addressed to this host.)
$IPTABLES -A INPUT -m state --state INVALID -j DROP
$IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
# ssh incoming, including non-standard port (if needed)
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT
# web serving, let's allow it! Both http and https ports
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 80 -j ACCEPT
# portmapper, in support of being an NFS-client
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 111 -j ACCEPT
$IPTABLES -A INPUT -p udp -m state --state NEW --dport 111 -j ACCEPT
# NFS serving (NFSv4 server offering NFSv3 back-compat)
# nail down the ports, by editing:
# /etc/conf.d/nfs, for OPTS_RPC_MOUNTD="-p 4002" and OPTS_RPC_STATD="-p 4000"
# /etc/sysctl.conf, for fs.nfs.nlm_tcpport = 4001 and fs.nfs.nlm_udpport = 4001
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 2049 -j ACCEPT
$IPTABLES -A INPUT -p udp -m state --state NEW --dport 2049 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 4000 -j ACCEPT
$IPTABLES -A INPUT -p udp -m state --state NEW --dport 4000 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 4001 -j ACCEPT
$IPTABLES -A INPUT -p udp -m state --state NEW --dport 4001 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 4002 -j ACCEPT
$IPTABLES -A INPUT -p udp -m state --state NEW --dport 4002 -j ACCEPT
# rsync serving
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 873 -j ACCEPT
# svn server
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 3690 -j ACCEPT
# nagios (5666); monitor time (123), allow snmp (161)
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 5666 -j ACCEPT
$IPTABLES -A INPUT -p udp -m udp --dport 123 -j ACCEPT
$IPTABLES -A INPUT -p udp -m udp --dport 161 -j ACCEPT
# amanda tape-backups; we reach out and tape things from this machine
$IPTABLES -A INPUT -p udp -m state --state NEW -m udp --dport 10080 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 10082 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 10083 -j ACCEPT
# OUTBOUND POLICY
# ===============
# of course, accepting loopback is a good idea
$IPTABLES -A OUTPUT -o lo -j ACCEPT
# (Applies to packets sent to the network interface from local processes)
$IPTABLES -A OUTPUT -j ACCEPT