Can putty to Cisco Nexus switches, but can't ssh from secure crt

[DSterling]

Recently we updated our Nexus C93180YC-FX to IOS nxos64-cs.10.2.6.m.bin. Prior to the update I could access using secure crt, now I can't access with secure crt, have to use putty.  I did a crypt key generate modulus 2048 and ssh key rsa 2048 force. No change. The result is connection closed, but with putty there is no problem. 

Thank you,

Dave

[MHM Cisco World]

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[DSterling]

I can't share the ssh key, the Nexus switch is on a secure network. I do see that the bitcount for 2 Nexus switchs I can still access with secure crt is 1024 and for the ones I can only access with putty it's 2048. 

When I do a show crypto key mypubkey rsa on the switches accessable with secure crt there is nothing displayed. 

When I do a show crypto key mypubkey rsa on the switches that are not accessable with secure crt (putty only):                                                                               Key label: SW name                                                                                                                                                                           key size: 2048                                                                                                                                                                                   exportable: no                                                                                                                                                                                   key-pair already generated

[Leo Laohoo]

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@DSterling wrote:
Recently we updated our Nexus C93180YC-FX to IOS nxos64-cs.10.2.6.m.bin. Prior to the update I could access using secure crt

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Look at the error message in the logs of the switch and compare the Key Exchange section of SecureCRT.  I am suspecting diffie-hellman is enabled and is on top of the list.

[DSterling]

diffie-hellman is not on, there are other diffe-helman features on, I unchecked them and still no success. I'm thinking it's a RSA key issue, but I'm not sure why. 

I do see that the bitcount for 2 Nexus switchs I can still access with secure crt is 1024 and for the ones I can only access with putty it's 2048. 

When I do a show crypto key mypubkey rsa on the switches accessable with secure crt there is nothing displayed. 

When I do a show crypto key mypubkey rsa on the switches that are not accessable with secure crt (putty only):                                                                               Key label: SW name                                                                                                                                                                           key size: 2048                                                                                                                                                                                   exportable: no                                                                                                                                                                                   key-pair already generated

[Richard Pidcock]

Are you using a saved SecureCRT session?  Have you tried deleting the saved session and then recreating it?  I'll be interested to find out as all of my Nexus switches are currently on 10.2.5.

[DSterling]

Tried a new session and no success. 

[DSterling · Accepted solution]

I had to update Secure CRT to a newer version, version 9.0.1, it was 8.5