Moxa DA-710-XPE [41/73] Nat network address translation

DA-710 Series Linux Managing Communications

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Example 5: Drop TCP packets addressed for port 21.

# iptables –A INPUT –i eth0 –p tcp --dport 21 –j DROP

Example 6: Accept TCP packets from 192.168.0.24 to DA-710-I-LX’s port 137, 138, 139

# iptables –A INPUT –i eth0 –p tcp –s 192.168.0.24 --dport 137:139 –j ACCEPT

Example 7: Log TCP packets that visit DA-710-I-LX’s port 25.

# iptables –A INPUT –i eth0 –p tcp --dport 25 –j LOG

Example 8: Drop all packets from MAC address 01:02:03:04:05:06.

# iptables –A INPUT –i eth0 –p all –m mac --mac-source 01:02:03:04:05:06 –j DROP

ATTENTION

In Example 8, remember to issue the command # modprobe ipt_mac first to load the module

ipt_mac.

NAT (Network Address Translation)

The NAT (Network Address Translation) protocol translates IP addresses used on one network into IP addresses

used on a connecting network. One network is designated the inside network and the other is the outside

network. Typically, the DA-710-LX connects several devices on a network and maps local inside network

addresses to one or more global outside IP addresses, and un-maps the global IP addresses on incoming

packets back into local IP addresses.

ATTENTION

Click on the following links for more information about NAT.

http://www.netfilter.org/documentation/HOWTO//packet

-filtering-HOWTO.html

NAT Example

The IP address of all packets leaving LAN1 are changed to 192.168.3.127 (you will need to load the module

ipt_MASQUERADE):