Find IP of Switch on Different Subnet?

[pinkled5]

I have acquired a used 3com managed switch. I strongly believe it was setup with a static IP, but I have no idea what network address it was using.

In order to access the web interface, I have to know the IP. IP scanning programs only work on your subnet and I don't know what network or subnet this was on. A wireshark capture didn't appear to capture any traffic from the device. I do not have a console cable nor do I know how to use one if I did.

Any suggestions?

 

[TheCrackLing]

Does it not have a serial console connection which you can use to completely reset it?

 

[imagoon]

That or use the reset to defaults procedure and then look at the manual's "getting started" section.

 

[pinkled5]

Does it not have a serial console connection which you can use to completely reset it?

I have zero experience with console connections. It does have a console port. I happen to have a cable lying around that seems to fit the console port and then connects to the Ethernet port of my computer. But I haven't a clue how to send commands over an Ethernet port to a console port, or if that would even fix my problem.

 

[pinkled5]

That or use the reset to defaults procedure and then look at the manual's "getting started" section.

There is no "reset" button or switch and I read the entire manual, it speaks nothing about a method to reset it to factory defaults. I suspect as a managed switch this may be security precaution.

 

[imagoon]

There is no "reset" button or switch and I read the entire manual, it speaks nothing about a method to reset it to factory defaults. I suspect as a managed switch this may be security precaution.

Yes there is. It is digital. You boot the switch with serial cable attached, interrupt the boot process per the prompt, select "Ignore current configuration." The switch now boots in factory original mode. You then type "initialize" to clear any remaining config.

There is no such thing as security once you have physical access.

 

[pinkled5]

Yes there is. It is digital. You boot the switch with serial cable attached, interrupt the boot process per the prompt, select "Ignore current configuration." The switch now boots in factory original mode. You then type "initialize" to clear any remaining config.

There is no such thing as security once you have physical access.

I've never used a serial cable before. I have a cable that connects to the console port on the switch then connects to the Ethernet port on my computer. But I started the switch with that cable connected and nothing like what you described happened. My guess is there are other steps to the process which you did not include, or the cable I have is not sufficient.

 

[imagoon]

I've never used a serial cable before. I have a cable that connects to the console port on the switch then connects to the Ethernet port on my computer. But I started the switch with that cable connected and nothing like what you described happened. My guess is there are other steps to the process which you did not include, or the cable I have is not sufficient.

Well #1 it would not connect to ethernet port. You would need a serial port on the your laptop or desktop. You then connect a serial cable to the switch. You then run a program like PuTTY and open a serial console. You then boot the switch. What model switch is it? I might be able to point you at the parts you need.

 

[avos]

This might depend on switch manufacturer, but I know on HP switches you can open up wireshark and look for LLDP_Multicast packets. The last section of that will list the Management Address.

No console cable or reset required.

 

[pinkled5]

Well #1 it would not connect to ethernet port. You would need a serial port on the your laptop or desktop. You then connect a serial cable to the switch. You then run a program like PuTTY and open a serial console. You then boot the switch. What model switch is it? I might be able to point you at the parts you need.

Interesting. I'd be hard pressed to find a PC with a serial port on it.

It's a 3com superstack 4400 (3c17204).

 

[pinkled5]

This might depend on switch manufacturer, but I know on HP switches you can open up wireshark and look for LLDP_Multicast packets. The last section of that will list the Management Address.

No console cable or reset required.

I did use wireshark but could find nothing of use in its data capture.

 

[imagoon]

Interesting. I'd be hard pressed to find a PC with a serial port on it.

It's a 3com superstack 4400 (3c17204).

Is that one with a 9 pin "D" console connection or does it look like another ethernet port?

If #1 I think you need a null modem cable. If #2 I think Cisco blue cables work.

You would then use something like an ICUSB2321F USB serial port in the laptop. Then connect the serial cables, use PuTTY to connect.

 

[alkemyst]

Interesting. I'd be hard pressed to find a PC with a serial port on it.

It's a 3com superstack 4400 (3c17204).

You would get a USB to Serial adapter. You really cannot do much with switches without this unless you always have the IP and other things.

You can try to plug into it and see if it hands out addresses.

Then possibly try X.X.X.1 or X.X.X.254

 

[alkemyst]

Is that one with a 9 pin "D" console connection or does it look like another ethernet port?

If #1 I think you need a null modem cable. If #2 I think Cisco blue cables work.

You would then use something like an ICUSB2321F USB serial port in the laptop. Then connect the serial cables, use PuTTY to connect.

USB to Serial adapter and a rollover cable.