Recover saved password pppoe session from router

There is a situation when you have been using the Internet through your router for a couple of years and, naturally, have forgotten or lost your password. Then the thought comes to mind to get a new device, you head off to the store, buy, bring home and ... you understand that there is no password anywhere. But like any thinking person, you understand that the router remembers everything, it remains only to convince him to tell him. It would be possible to check it in the settings of the router, but, unfortunately, this method is not suitable for all models. I'll tell you about the universal way to find out the password.

You will need:
1) Your router
2) Patch cord (normal, not cross)
3) Computer with Linux on board.


First of all, you should put 2 packages on a machine on Linux: ppp and rp-pppoe . As you probably understood, this is a pppoe server. After successful installation, proceed to the configuration.
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Edit the /etc/ppp/pppoe-server-options file as follows:
require-pap
login
lcp-echo-interval 10
lcp-echo-failure 2
show-password
kdebug 2
debug

Next, let's get down to /etc/ppp/pap-secrets :
# Secrets for authentication using PAP
# client server secret IP addresses
dsl_user * "" *
where dsl_user replace your username from pppoe (you can find it in the admin panel of the router)

Now we will begin the main stage - start of the server.
$ pppoe-server -F -k -I eth0
If errors are displayed, you first need to disable the already existing connection to your eth interface and then try again.

And now we will create magic. Turn off the router and connect the patch cord to the WAN port of the router and the LAN port of your network card from a Linux computer. After that, you can turn on the router back and the magic will start. You will not see it, but you will feel, and maybe not. This is no longer important, because in /var/log/messages.log or /var/log/everything.log your password will be specified in plain text.

Then just put everything back and set up your new router.

PS In the same way you can find out the password of your friend, just being at his home, you never know why it will be useful to you.