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Ask the Expert- SD-WAN

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VIP Collaborator

3750 SSH Log.

Hello!

I was reviewing at my SW-3750 logs and I found this serie of outputs:


May 19 13:10:57: SSH2 0: kex algo not supported: client diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group1
May 19 13:10:57: SSH2 1: kex algo not supported: client diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group1

I searched in internet about this and I did not find information. I do not know if this is a bug or it's really a problem. Thanks in advance for any information, answers or solution you can give me.

Regards,

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Cisco Employee

Hi Diana,

Hi Diana,

Some of the SSH clients that are connecting to this 3750 have offered to use a set of cryptographic algorithms that is not supported by this switch, and that is the cause of the message you are seeing.

This does not indicate any error per se. Are there also any other messages around this one that contain the IP address of the client? It would be interesting to know what software has been used to connect to your switch.

If your clients do not have issues connecting to the switch via SSH then you do not need to worry.

Best regards,
Peter

4 REPLIES 4
VIP Advisor

Hi Diana,

Hi Diana,

Unfortunately I'm not familiar with these logs, I think a debug ip ssh could provide more information. 

Hall of Fame Cisco Employee

Hi Diana,

Hi Diana,

Some of the SSH clients that are connecting to this 3750 have offered to use a set of cryptographic algorithms that is not supported by this switch, and that is the cause of the message you are seeing.

This does not indicate any error per se. Are there also any other messages around this one that contain the IP address of the client? It would be interesting to know what software has been used to connect to your switch.

If your clients do not have issues connecting to the switch via SSH then you do not need to worry.

Best regards,
Peter

VIP Collaborator

Hello Peter!

Hello Peter!

Thank you for your response. I use SuperPutty to connect to my devices and I've not problem to connect them. There is not any other Logs in my Switch.

Thanks a lot!

Highlighted
Beginner

Re: 3750 SSH Log.

This is the basic problem with the third party client application e.g. putty, super putty, secure crt which uses its own algorithm to exchange the encryption key with the device which is being accessed through ssh. So the best idea is to use putty only, if there is issue with then try other one.

Refer attachment.

Acknowledge if found helpfull.