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-   -   Get IP address (

jeyram 09-02-2007 08:10 AM

Get IP address
i am working in software development side. i am not much familiar in networking area. i want small help.
i am using Ubuntu Linux. i connected my pc to a switch. i want to telnet that switch. but i don't know that switch ip address. how can i get that ip address?

oskar 09-02-2007 08:48 AM

Switches are usually dumb as a stick. They don't have an IP, and you can't telnet to them. You're thinking of a router.

Brian1 09-02-2007 09:26 AM

Yes a switch can have a telnet port like a smart switch like a 3com 3300 switch can be access with a web browser and telnet access. The only way to find if you don't know the ip is use a tool like nmap to scan the entire segment of the IP's used. For example if say your current IP is and a subnet of then this is a class C address and you can scan all 255 IPs ranging from to With nmap it has and OS type detection map that may identify the OS the device is using. The fingerprinting it uses is not perfect but gets close. There are serveral gui interfaces for nmap if console use is not your thing.


oskar 09-02-2007 09:56 AM

I stand corrected.

ikehack 09-02-2007 09:56 AM

Yeah, as Brian1 said you might want to "trial and error" with nmap. But if it's a switch and doesn't have an IP Address isn't it more than likely controlled via serial I/O? As in you need to hook up to the switch via serial connection and configure it that way.

Brian1 09-02-2007 11:42 AM

Post the brand and model of the switch and we can all see what it is and not.


jeyram 09-02-2007 02:32 PM

Brand: cisco
Cisco 1900 Series switch

* any way i am very thankful for your attention. i got this switch from my friend and i am using this switch in my home for sharing internet connection. if you think this is some kind of mess then just tell me, i will drop this part.
because just i try to configure some thing in this switch. but if you get any idea i will glade to all of you.
-thanks again.

soroccoheaven 09-02-2007 02:40 PM

dont you now its wan port IP ?

soroccoheaven 09-02-2007 02:42 PM

how is this connected to your network ?

soroccoheaven 09-02-2007 02:55 PM

ok..the switch probably does not have an IP address, unless it is actually a router (not for you if it is cisco 1900 !!). To find out, just run a tracert *win or 'traceroute' on *nix from your desktop machine to the any outside server. It will list all nodes with assigned ip numbers that are visited along the path from your desktop to the outside server.

Brian1 09-02-2007 03:54 PM

So many different models using the 1900 reference. If it came from someone else and you don't know the IP then it could be anything. If it has a serial port then you would have to turn it off, connect to the serial port with a null serial cable I beleieve, and start a terminal serial client app, turn on the switch and try making connection. The exact steps I don't know. Should be able to find all that info from cisco site. That is if it has a serial port.


jeyram 09-02-2007 10:04 PM

thanks Brain,
i used console cable and i assigned new ip address.
thank you very much to all of you.

Brian1 09-03-2007 10:18 AM

Glad to be of help. Just out of curiosty what was the old IP anything close to you network IP range?


jeyram 09-05-2007 01:42 PM

i don't know my old ip address.
if you use console cable you can reset any thing(password also).
i found this way in some ccna certifications slides.

TBKDan 09-05-2007 01:49 PM

From what I remember, you don't have to reset the switch/router to connect via serial. Just connect the null cable, start up your client, and just hit enter... you should get the prompt :)

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