TechInfoDepot:DD-WRT/Script Examples

Which IP addresses and hostnames are used for wireless clients?
Note: Only work if you get an IP address from DHCP

Output:

You can change the order of "$1, $2, $3" or cut-out:

Output:

if you want to show this in a browser remove the # and use:

To booting on startup see Startup Scripts

''How can I protect this file? I want to allow showing this only if you are logged in the web interface!'' Please write it here, thanks

answer:name it wlan.asp 57032956191056854646430

"How can I output the signal strength (wl rssi ) at the same time by feeding MAC Addr from assoclist without typing MAC addr each time in telnet?"

Keep ISP from disconnecting due to lack of traffic
Some internet service providers will drop the connection if there is no traffic for some period of time (idle time-out). With these scripts you can prevent this.

If this does not work (providers ignores ICMP packets as traffic) use:

To run these scripts, save to a local file, make executable with 'chmod a+x ' and run with './filename'

How many connections are open for each IP address?
For each active IP address on the local network (assumed to be a 192.168.x.0 network below), this prints out the number of connections that this IP address has open to hosts on the Internet. "Connections" includes both TCP and UDP - while there are no "UDP connections", Linux maintains NAT-related information about UDP traffic which is similar to that for TCP.

This is handy for finding that person in your LAN whose P2P software opens many hundreds of connections, making the network slow for everybody.

The last command (sort -gr) sorts the results by number of connections, with the biggest number first.

Signal strength
Small one line scripts to give a signal level display in the style of the Linux 'wavemon' program.

wl interface
If you are using the WRT in client mode and connecting it to another AP, you might want monitor the signal level that you are receiving at the client wrt. To do this we use the 'wl' command to access the details from the wireless driver.

gives the signal strength in dB and gives the noise level in dB.

The only problem with this is that different versions of the firmware give different outputs. Versions of DD-WRT firmware up to v23 give

as the output to 'wl rssi', but version 24 just gives the number only without the "signal is " bit. This means that scripts which use the outputs from the wl command must be chosen for the different firmware versions.

In client mode
We are interested in the signal to noise figure and in monitoring it continuously, so we need a small script to do it. I also decided that it would be useful to display a small graph of the s/n figure. This is an ugly script as I had to optimise it to get it to work fast enough to be useful on the slow WRT processors :(, but this does mean that it can easily just be cut and pasted into a telnet or ssh session onto the wrt as an ugly one-liner.

Firmware v24
The output will look a bit like this:

To terminate, just press + c

When using a WRT54GL v1.1 (bought 23/May/08) with dd-wrt v24 std generic, I was able to tweak the script to the following to give meaningful SNR numbers:

(This was during testing with the new WRT54GL in Client Bridge mode about 3m away from my (older) access point (Netgear WGR614).)

Rockus 10:42, 24 May 2008 (CEST)

In AP mode
Using it in AP mode is more difficult as firstly, you have to supply the MAC address of the client that you want to monitor, and secondly as I havent been able to get the 'wl' command to give a meaningful noise figure so you have to guess of what you think that the noise figure is.

(Note : I have yet to test this on firmware v24, but if it is the same as the client mode, then the following should work -- also need to test if the noise figure works for v24)

You will have to replace  with the MAC address of the client that you wish to monitor, and replace  with a guess of what you think that the noise level is at your location. I used the figure 97 as my guess for the noise level, but it is very likely that it will be different at your location.

Having to add in the noise fudge factor will probably mean that the signal to noise figure that you get will be wrong, but the script is still useful as it will give a graph which can show you the RELATIVE strength as you move the client around the room.

(If anyone knows how to get a correct noise figure, please either add it here or in the discussion tab)

Miscellaneous tweaks
Note: SMB or WGET may be substituted for JFFS on limited flash memory devices.

Log your startup
Requires JFFS. Save your startup commands to /jffs/startup.sh

Example:

Make this file executable:

Save the following line to startup: (use administration/diagnostics, save startup)

Your standard and error output from the scripts will be viewable in /tmp/startup.log. /tmp is stored in volatile memory (RAM) and will be erased each startup showing only the current error or success messages. It is not recommended to use /jffs for logs due to increased flash wear. Use the echo command to label sections of your startup file and verbose command options for troubleshooting.

Change root username
Replace 'emanymton' with your username. Save this as a startup script.

Or a simpler way

or even

Here -i stands for "in place" and -e introduces the sed command expression

Store user web on JFFS
Requires JFFS. Create /jffs/www.

Save this as a startup script:

Place your content in /jffs/www/index.html and other files in that same directory.

The default location is

Require PPTPD encryption
Requires JFFS, PPTPD. Copy /tmp/pptpd/options.pptpd to /jffs and edit.

Insert the following:

Save the following as a startup script:

Use freedns dot afraid dot org as DDNS
Create a Jffs partition and copy this script as /jffs/etc/config/ddns.wanup

Change "dot" to "."

Don't forget to do

Then you can execute it to verify that it works. A temporary file will be created in $ip_cache.