You can't. To sniff it would mean that someone else has the username/password, and you would sniff it out of the network traffic to the router. Since you don't KNOW what it is, you can't sniff it. You'll probably have to reset the router, then reset your username/password, and restore the backup of the config that you saved when you configured the router. You did backup the settings, right? :)

How can i backup it?

The manual should have directions for backing it up. It depends on the manufacturer, but most if not all of them have a menu option to backup the config, once you're able to access (login) to it.

who is the router provider?

You would be able to backup the router's configuration by logging into the router , if at all it has a user interface , otherwise through the console.

To log into the router you need log in credentials.

if you will able to reset your router only after that you can create backup

zzz. Why Not Reset The Router?? It Is So Damm Easy To Make A Password And Username Back.. I Will Give The Site For LINKSYS And I Think It Is For All Routers Because I Use Another Brand Router And It Is Avaliable.. The Link Will Be Given Below This Statement
http://192.168.1.1/

So , They Should Ask For The Username And Password.. Both Of Them Should Be : admin
The Username ANd Password Should NOT Have Space And Should NOT Have Caps...

So You Should Reach The Site Which Say Linksys On The Left Right Corner...

You Should See Big Words (E.g) (Setup And Wireless And Many More)

Click On Wireless.. You SHould End Up In Basic Wireless Settings...

They Would Ask For The Wireless Network Mode.. The Wireless Network Mode Should Be Shown On On Router Or On Your Box Of Your Router...

Wireless Network Name(SSID) Is The Name Of Your Router.. When You Search For Wireless Network Your SSID Name Should Be There

The Wireless Channel MUST BE (6-2.437GHz)

Wireless SSID Broadcast MUST BE Enabled If Not You Cannot Find Your Router SSID When You Search For Wireless Network

Once You Are Done Press Save Settings And You Should See Your Power Button Blinking...
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The Previous One I Just Told You Is The One Where You Set The SSID And Is The Username

Now I Am Gonna Tell You How To Set Your Password So It Is Secured

_____________________________________________________________________________________

As I Told You, You Should Press Wireless.. But Below The WIreless , You Should See Wireless Security.. You Should Click On It And Wait For It To Load..

The Security Mode Must Be WPA Pre-Shared Key

The WPA Algorithms Is : TKIP

The WPA Shared Key Is Your Router Password To Enable Your Secure. So Please Type In Your Password For Your Router...

The Group Key Renewal Should Be Entered.. It Should Be: 3600
_____________________________________________________________________________________

Once You Are Done Press Save Settings And You Should See Your Power Button Blinking...

You are replying to a four year old thread, I imagine he has sorted the problem by now...

Thread closed.