DD-WRT Config Backups

So the other day I managed to hose my DD-WRT configuration at home, badly enough that I figured I really ought to back up my config so I don’t wind up trying to reconstruct my config from memory.

(If you just want to see the script, you can jump ahead.)

I have nightly backups of my desktop (and so do you, right? Right?!) so I figured the simplest thing is just to copy the router’s config to my desktop, and let it be swept up with the nightly backups. So then it’s just a question of getting the configuration and such to my desktop.

In DD-WRT, under “Administration → Backup”, you can do manual backups and restores. This is what we want, except that we want this to happen automatically.

The trivial way to get the config is

curl -O -u admin:$PASSWORD http://$ROUTER/nvrambak.bin

or

wget --http-user=admin --http-password=$PASSWORD http://$ROUTER/nvrambak.bin

where $ROUTER is your router’s name or IP address, and $PASSWORD is your admin password. But this sends your password over the network in the clear, so it’s not at all secure.

Instead, let’s invest some time into setting up ssh on the router; specifically, the public key method that’ll allow passwordless login.

Go follow the instructions there. When you come back, you should have working ssh, and a key file that we’ll use for backups.

Back? Good. Now you can log in to the router with

ssh root@$ROUTER

and entering your password. Or you can log in without a password with

ssh -i /path/to/key-file root@$ROUTER

Once on the router, you can save a copy of the configuration with nvram backup /tmp/nvrambak.bin. So let’s combine those last two parts with:

ssh -i /path/to/key-file root@$ROUTER "nvram backup /tmp/nvrambak.bin"

And finally, let’s copy that file from the router to the desktop:

scp -i /path/to/key-file root@$ROUTER:/tmp/nvrambak.bin /path/to/local/nvrambak.bin

So the simple script becomes:

#!/bin/sh
SSH=/usr/bin/ssh
SCP=/usr/bin/scp
RSA_ID=/path/to/keyfile_rsa
ROUTER=router name or IP address
LOCALFILE=/path/to/local/nvrambak.bin

$SSH -4 -q ${RSA_ID} root@${ROUTER} "nvram backup /tmp/nbrambak.bin"
$SCP -4 -q ${RSA_ID} root@${ROUTER}:/tmp/nbrambak.bin ${LOCALFILE}

I’ve put this in the “run this before starting a backup” section of my backup utility. But you can also make it a daily cron job. Either way, you should wind up with backups of your router’s config.

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