Console access

[corey.burden]

Hello,

I'm trying to connect to a device's console port through an ISR431.  It's a new router out of the box.  When I connect a laptop to the console port, it works just fine.  When I connect the router to the 4351 and try to SSH to the VTY line, I don't get a response.  This is the second device that is having this symptom.  I used a known working port on the 4351 that works with an existing router and it comes up just fine through the 4351.  Does anyone have any suggestions or know what may be the issue here?

[balaji.bandi]

Since you have console access, you can see the show run, what config it has as shipped.

here is a quick installation guide - it required quick setup :

https://www.cisco.com/c/en/us/td/docs/routers/access/4400/hardware/installation/guide4400-4300/C4400_isr/initconfig.html

[Martin L]

My guess is that they protect device ( SSH to the VTY line)  access for security reasons. you must configure it first after accessing it via console

Regards, ML
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[Richard Burts]

I am confused about this post. In the beginning it says "I'm trying to connect to a device's console port through an ISR431." But then it talks about using SSH to access it. I suspect that this is a new device and that it has not yet been configured with an IP address for its interfaces. And has not yet generated the RSA key that is required for SSH to work. Can you confirm that this is the case?

[corey.burden]

So, Im connecting to the console port via ssh to ISR.  The command would be something like ssh -l <username>:30@192.168.1.1.   That would take me to the vty line that's connected to the console port.   It works with an existing router that is connected to that port.  I just moved the connection to the new router but then it doesn't work.  I see my authentication pass but from there it's not connecting to the vty line.

[corey.burden]

Good point.  I can check it on this device but the first one I used I set up SSH and generated and RSA key but still couldn't connect to the VTY port

[Richard Burts]

I am still confused about what we are dealing with. The question seems to be combining console and SSH. Console access is one thing and is accomplished using a cable that physically connects to the router. SSH is for remote access to the router and uses vty ports and is different from console access.

There are terminal servers (which can be implemented on Cisco routers where the terminal server has physical connections to console ports. You might SSH to the terminal server and then it uses reverse telnet to access the console ports. Is that what we are dealing with?

Let me go back to part of the post " When I connect a laptop to the console port, it works just fine. When I connect the router to the 4351 and try to SSH to the VTY line, I don't get a response." I interpret that to mean that the console does work ok and that there is a problem with SSH access. As a first step in troubleshooting can you ping to the address that you are attempting to use for SSH?

If ping is successful then there is basic IP connectivity and the problem seems to be with SSH. Use the console and post the output of the command show ip ssh

If ping is not successful there is a problem with basic IP connectivity. Use the console and check whether the interface is configured with the right IP address and whether the router has a route to your address - if you are not in the local subnet with the router.

[balaji.bandi]

you need to follow the guide which i was suggested to get router running first with basic setup, if that is done,

still now working--

from console issue command -

show run (post complete config, by removing any passwords)

from what device you try to SSH (what is the IP address of devices ?) are you able to ping Router IP from the device(PC) before you try SSH ?

[Dmitriy Ivanov]

Was about VTY config?
Do you have "transport input ssh" there?

I think you need to read this: https://www.cisco.com/c/en/us/support/docs/security-vpn/secure-shell-ssh/212142-Configure-SSH-on-Tty-Lines-with-Menu-Opt.html

[johnlloyd_13]

hi corey,

just to be clear on what you're trying to achieve, you want to SSH to the "new" router from an existing/working 4351?

can you post a 'show run' from both the new router and 4351? try to temporarily remove the ACL applied on the VTY, if any.

also post the 'show line' output from the new router. it could be the VTY lines are stuck/stale due to troubleshooting.

you could clear them with the 'clear line vty <number>'

[Dmitriy Ivanov]

i think what he is doing is this- he has terminal server c4351, he ssh to that terminal server and ftom that terminal server he connects to the new router via hydra cable, after that you normally telnet to that line but he wants to do ssh. he said it works with another lines. it is not clear if that terminal line is new or it works with the old router.