Today, almost everyone has more than one computer at home, and, thus, there are many wireless LANs. For example, in my neighbourhood I can see at least 12 wireless LANs, when seven of them use no encryption. Moreover, five of them still didn't change their default router access username/password.So, anyone is able to configure it easily.
When I got interested in networks hacking/security, I was wondering if it is possible to retrieve ADSL username and password from router configuration screen.
Every router I tried, has at least 2 access ways - HTTP Web service (mostly used), and Telnet service.Both ways demand connection to the LAN.So, if the wLAN communication encrypted, you can try to crack it. Read here, how to do this.
In order to enter to the router configuration, write in browser address bar the IP address of router. Usually, the default username/password for router config are "Admin/Admin" (D-link, Siemens) or "admin/adminadmin" (3Com). Anyway, you can find it in the Internet, if you know router model. If you're lucky, your lame neighbours didn't change default settings.
In most cases, when I tried to see Internet connection properties of router, I could see only username, and the password usually was masked with asterisk symbols, and there is no option to use java<b></b>script to unmask it. Sometimes, the username/password fields even disappear after a short time period. So, it's impossible to retrieve password in this way, however, it useful to see username and to enable remote administration, if disabled.
After the remote administration has been enabled, it is possible to connect to router's telnet service. If you use Windows, you can do it in command line prompt (cmd) or hyper-terminal, just type "telnet router ip address. Use the same username/password to get into router configuration you entered in Web config mode. When you are inside, type "dumpcfg" command. If this command is not valid, try "?" or "help" to figure which command will show you router settings dump (in my short experience, dumpcfg works on most routers). After you typed the command, you will get a long list of different settings. You must look for something like "<ppp_conId...". In that line, you will see 2 parameters (usually, userName="some long number" password="another long number"). The long hex numbers between quotation marks are encoded username and password for ADSL connection. Each pair of digits equals to a single letter/digit, as shown:
I think it is some standard encoding. Anyway, you can check it by comparing the known ADSL username and its encoded equivalent, and to build your own table. After you finish password decoding, you can try to connect to the Internet using your ADSL modem.
Conclusion: if you have wireless LAN, be sure you protect yourself, as it's written here, and have a good time!
P.S. Sorry for my english grammar. Hope you learned something new. Thanks, lxgreen.