User`s manual

UC-7400-LX Plus User’s Manual Managing Communications

4-8

Example 4: Drop TCP packets from 192.168.1.25.

# iptables –A INPUT –i eth0 –p tcp –s 192.168.1.25 –j DROP

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 UC-7400-LX Plus’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 UC-7400-LX Plus’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

NAT

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

different IP addresses used on another network. One network is designated the inside network and

the other is the outside network. Typically, the UC-7400-LX Plus 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.

NOTE

Click on the following link for more information about iptables and NAT:

http://www.netfilter.org/documentatio

HOWTO/NAT-HOWTO.html

NAT Example

The IP address of LAN1 is changed to 192.168.3.127 (you will need to load the module

ipt_MASQUERADE):

Embedded Computer

PC1 (Linux or Windows)

IP/Netmask:

Gateway:

192.168.3.100/24

192.168.3.127

PC2 (Linux or Windows)

IP/Netmask:

Gateway:

192.168.4.100/24

192.168.4.127

LAN1

LAN2

LAN1: 192.168.3.127/24

LAN2: 192.168.4.127/24

NAT Area / Private IP

1. #echo 1 > /proc/sys/net/ipv4/ip_forward

2. #modprobe ip_tables

3. #modprobe ip_conntrack

4. #modprobe iptable_nat

5. #modprobe ipt_MASQUERADE

6. #iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE