Firewall INPUT filters

INPUT view

Basic inputs

You can find the basics INPUT rules over here: Firewall core (main) protocols

SSH

# SSH - max 3 connection request per minute
$IPTABLES -A INPUT -p tcp -m limit 3/min --limit-burst 3 --dport 22 -j ACCEPT

Web server

You have to open the following ports:

• Port 80 = HTTP
• Port 443 = HTTPS

$IPTABLES -A INPUT -p tcp -m state -i eth0 --dport 80 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state -i eth0 --dport 443 -j ACCEPT

DHCP

This is how you enable a DHCP server with TFTP (netBoot) :

IPTABLES=`which iptables`

# Allow LAN communication
# ... Required for NFS and the NetBoot ...
$IPTABLES -A INPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
$IPTABLES -A OUTPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
 
########################
# INPUT filters
########################
 
##### DHCP client ######
# Broadcast IP request 
$IPTABLES -A OUTPUT -p udp -d 255.255.255.255 --sport 68 --dport 67 -j ACCEPT
# Send / reply to IPs requests
$IPTABLES -A INPUT -p udp -s 255.255.255.255 --sport 67 --dport 68 -j ACCEPT
 
###### DHCP server ######
# Received client's requests [udp + tcp]
$IPTABLES -A INPUT -p udp --sport 68 --dport 67 -j ACCEPT
$IPTABLES -A INPUT -p tcp --sport 68 --dport 67 -j ACCEPT

# NetBoot - TFTP server
$IPTABLES -A INPUT -p udp -s $LAN_ADDRESS --dport 69 -j ACCEPT
 
 
########################
# OUTPUT filters
########################
# DHCP [udp + tcp]
$IPTABLES -A OUTPUT -p udp --dport 67 -j ACCEPT
$IPTABLES -A OUTPUT -p tcp --dport 67 -j ACCEPT
$IPTABLES -A OUTPUT -p udp --dport 68 -j ACCEPT
$IPTABLES -A OUTPUT -p tcp --dport 68 -j ACCEPT
 
# TFTP NetBoot 
$IPTABLES -A OUTPUT -p udp --dport 69 -j ACCEPT

Note the difference between the broadcast request that every computer should allow and the plain OUTPUT allow on ports 67,68 for the DHCP server !!

LDAP

$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 389 -j ACCEPT # LDAP
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 636 -j ACCEPT # LDAPS

NFS

It's really tricky to adjust the firewall for NFS as the port is dynamic. But option is to allow LAN traffic and use NFS over LAN only.