Port Blocking

From DD-WRT Wiki

(Difference between revisions)
Jump to: navigation, search
Revision as of 07:14, 5 January 2008 (edit)
Cyph3r (Talk | contribs)
(External Resources)
← Previous diff
Revision as of 07:14, 5 January 2008 (edit) (undo)
Cyph3r (Talk | contribs)

Next diff →
Line 6: Line 6:
:''FTP = Port 21'' :''FTP = Port 21''
-In order to set rules on specific ports, you need to access iptables. You will have greater control accessing the iptables via telnet or SSH. If you feel more comfortable running commands via the router's web interface, then you can do so by logging into your router's Administration/Diagnostics page. From there you can input your desired commands into the Command Shell.+In order to set rules on specific ports, you need to access iptables. You will have greater control accessing the iptables via SSH or Telnet. If you feel more comfortable running commands via the router's web interface, then you can do so by logging into your router's Administration/Diagnostics page. From there you can input your desired commands into the Command Shell.
== Commands == == Commands ==

Revision as of 07:14, 5 January 2008

This tutorial will show you basic commands for blocking service ports from communicating with your network.

Example:

Web = Port 80
FTP = Port 21

In order to set rules on specific ports, you need to access iptables. You will have greater control accessing the iptables via SSH or Telnet. If you feel more comfortable running commands via the router's web interface, then you can do so by logging into your router's Administration/Diagnostics page. From there you can input your desired commands into the Command Shell.

Commands

Port Blocking - Block all users to this port (Example: Port 80):

iptables -I FORWARD 1 -p tcp --dport 80 -j DROP

Port Blocking - Block a SINGLE user to this port (Example: Port 21):

iptables -I FORWARD 1 -s 192.168.1.101 -p tcp --dport 21 -j DROP

List iptables - List the rules in a chain or all chains:

iptables -L

Undo Rule - Delete rule rulenum (1 = first) from chain:

iptables -D FORWARD 1

Flush Rules from iptables - Delete all rules in chain or all chains:

iptables -F

Multiple Ports - Use a semi-colon to separate multiple ports:

iptables -I FORWARD 1 -p tcp --dport 80 -j DROP; iptables -I FORWARD 1 -p tcp --dport 21 -j DROP

Port Range - Use a colon to select a port range (Port 21 through 80 will be closed):

iptables -I FORWARD 1 -p tcp --dport 21:80 -j DROP

External Resources

Iptables command - Lists all available commands for use in iptables
PortForward - List of the most commonly used ports
SSH and the Command Line - How to on Telnet and SSH