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DD-WRT is an opensource linux based firmware for Linksys WRT54G and similar 802.11g wireless routers.

Wiviz, an open source GPL project, allows you to use your WRT to see other networks. It scans for networks and then shows signal strength and effects of antenna adjustment in real time.

Redirect all SMTP traffic to your internet providers SMTP server

Let DD-WRT redirect SMTP traffic to a valid SMTP server so everyone on your net can send mail

Use DD-WRT Router as WiFi Range Extender

How DD-WRT routes traffic

To get a better understanding on how DD-WRT routes traffic, you can read:

If you are interested it tells how to show routing information:

To list your currently active rule-set: iptables -L

This command should list your currently active rule-set, and translate everything possible to a more readable form. For example, it will translate all the different ports according to the /etc/services file as well as DNS all the IP addresses to get DNS records instead. The latter can be a bit of a problem though. For example, it will try to resolve LAN IP addresses, i.e., to something useful. is a private range though and should not resolve to anything and the command will seem to hang while resolving the IP. To get around this problem we would do something like the following:

iptables -L -n

Another thing that might be interesting is to see a few statistics about each policy, rule and chain. We could get this by adding the verbose flag. It would then look something like this:

iptables -L -n -v

Don't forget that it is also possible to list the nat and mangle tables. This is done with the -t switch, like this:

iptables -L -t nat

There are also a few files that might be interesting to look at in the /proc file system. For example, it might be interesting to know what connections are currently in the conntrack table. This table contains all the different connections currently tracked and serves as a basic table so we always know what state a connection currently is in. This table can't be edited and even if it was possible, it would be a bad idea. To see the table you can run the following command:

cat /proc/net/ip_conntrack | less

The above command will show all currently tracked connections even though it might be a bit hard to understand everything.

Virtual Interfaces multiple SSID's

Wireless Access Point

Do a hard reset on the router

  1. Connect the router directly (to avoid conflicts with other stuff on your network) to one of the switch ports on the router (not the WAN port)
  2. Connect to the router
  3. Chose a username and password, and login to the router

Go to the Setup - Basic Setup tab

  1. Set WAN Connection Type to Disabled
  2. Check Assign WAN Port to Switch (visible only when WAN Connection Type is set to Disabled)
  3. Set Local IP Address to or something that fits your existing network different from primary router and out of your DHCP pool
  4. Set Subnet Mask to or whatever you use on your network
  5. Set DHCP Server to Disable
  6. Uncheck Use DNSMasq for DHCP
  7. Set Gateway to or whatever your local gateway is (NTP Client and many things will fail without this)
  8. Set Local DNS IP address of primary router (NTP Client and many things will fail without this)
  9. Save

Go to Setup - Advanced Routing tab

  1. Set Operating Mode to Router
  2. Save

Go to Wireless - Basic Settings tab

  1. Enter the name of your wireless network in Wireless Network Name (SSID)
  2. Set Wireless Channel to Auto
  3. (Optional) Sensitivity Range: The max distance (in meters) to clients x2
  4. Save

Go to Wireless - Wireless Security tab

Note: Security is optional, but recommended! Clients must support whatever mode you select here.

  1. Set Security Mode to WPA2 Personal Mixed
  2. Set WPA Algorithm to TKIP+AES
  3. Enter the password for your network in WPA Shared Key (at least 8 characters)
  4. Save

Go to Services - Services tab

  1. Set DNSMasq to Disale
  2. Set ttraff Daemon to Disable
  3. Save

Go to Open the Security - Firewall tab

  1. Uncheck all boxes except Filter Multicast
  2. Save
  3. Set SPI firewall to Disable'
  4. Save

Go to Administration - Management tab

(Recommended) Info Site Password Protection: Enable

  1. Set Routing to Disabled
  2. Apply Settings
  1. Connect Ethernet cable to main router you can use the WAN connection, or any of the LAN ports

Netgear WNDR3700 and DD-WRT

Netgear WNDR4000 and DD-WRT

Port forward problem

Netgear WNDR4500 and DD-WRT

Extend the range of your wireless network

Commercial antenna

Do it yourself antenna

WDS (Wireless Distribution System) Repeater for range extension