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Howto Deploy Ethernet MAC Address Filtering on CommGate 3.x

  1. Download Notepad++ from http://notepad-plus.sourceforge.net/uk/site.htm to edit the following text files from a Windows PC. You can then convert the text files into Windows and UNIX modes easily.

  2. Using Notepad++, create a text file and save it as rc.firewall.macaddr in /etc/rc.d directory.

  1. Add all the Ethernet MAC Addresses into file /etc/rc.d/rc.firewall.macaddr (one MAC Address per line) to filter it via the firewall rules in the following format;

MACADDRS="\
11:22:33:44:55:66 \
aa:bb:cc:dd:ee:ff \
66:55:44:33:22:11"

Note: Please change the MAC addresses with your own.

  1. Using WinSCP3 (downloadable from http://winscp.net/eng/download.php), login to the CommGate 3.x system as user root and double-click on the following file /etc/rc.d/rc.firewall.local (Note: Save a copy of the original file for backup purposes before you edit it as a precaution).

  1. Add the customize rules to filter Ethernet MAC Address on the CommGate Shield 3.x firewall script located in /etc/rc.d/rc.firewall.local to allow traffic for authorized MAC addresses to the Internet or WAN interface (eth0).

Copy and paste these lines:

## Start of Ethernet MAC Address firewall script.
## The Ethernet Mac Address file must be located
## at "/etc/rc.d/rc.firewall.macaddr".
MACADDRS=`cat /etc/rc.d/rc.firewall.macaddr`

# This is where the IPTABLES firewall binary
# is located within the CommGate system.
IPTABLES=/sbin/iptables

# Create special table for Ethernet MAC Address

# Filtering with a table/chain name mac-allowed.
$IPTABLES -t nat -F mac-allowed 2>/dev/null
$IPTABLES -t nat -X mac-allowed 2>/dev/null
$IPTABLES -t nat -N mac-allowed

# Insert MAC address check into the
# NAT+PREROUTING table
$IPTABLES -t nat -I PREROUTING -i eth1 -j mac-allowed

# Add MAC addresses to our special table
for MAC in $MACADDRS; do
$IPTABLES -t nat -A mac-allowed -i eth1 -m mac --mac-source $MAC -j RETURN
done

# Drop all unrecognized MACs and change the
# LAN IP subnet 192.168.1.0/24 to your own
# LAN subnet. Refer to this website to
# calculate your Subnet Mask suffix as
# /24, /23, /32, etc.
$IPTABLES -t nat -A mac-allowed -i eth1 -d ! 192.168.1.0/24 -j DROP

## End of Ethernet MAC Address firewall script.


  1. Finally, check to make sure that the rc.firewall.macaddr file is uploaded to /etc/rc.d/ directory on the CommGate Shield system and restart the firewall as follow;

    service firewall restart

  2. Start testing your Internet/WAN access.

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