in the past i can access to my routers over SSH now after upgrade to the latest version i can't login to any router and the error is related to SSH connection
when i try to add new router also i have the same problem with ((( The authenticity of host "x.x.x.x" can't be established. RSA Key fingerprint is unavailable))).
I upgrade to the last release and the same issue .
this is the log on my router since i use radius server with username and password to login to my routers over SSH
RP/0/RP0/CPU0:Jul 11 07:20:05.945 GMT: SSHD_: %SECURITY-SSHD-6-INFO_GENERAL : Client closes socket connection
RP/0/RP0/CPU0:Jul 11 07:20:05.946 GMT: SSHD_: %SECURITY-SSHD-3-ERR_GENERAL : Error in receiving key exchange packet
RP/0/RP0/CPU0:Jul 11 08:11:05.516 GMT: SSHD_: %SECURITY-SSHD-6-INFO_GENERAL : Client X.X.X.X closes socket connection
RP/0/RP0/CPU0:Jul 11 08:11:05.518 GMT: SSHD_: %SECURITY-SSHD-3-ERR_GENERAL : Failed in version exchange
RP/0/RP0/CPU0:Jul 11 08:11:07.955 GMT: SSHD_: %SECURITY-SSHD-6-INFO_GENERAL : no matching kex found: client ssh-rsa server ssh-dss
As your log notes:
no matching kex found: client ssh-rsa server ssh-dss
Try updating your client software (putty etc.) to a newer version. Newer IOS versions have deprecated the older ssh-rsa key exchange.
This is caused by Cisco CLI Analyzer only supporting RSA.
You should generate an RSA host key for network devices, unless a better type is available.
If you want to add other key types to Cisco CLI Analyzer, see: https://community.cisco.com/t5/cisco-cli-analyzer/cli-3-6-7-authenticity-of-rsa-fingerprint-cannot-be-verified/m-p/4390271/highlight/true#M476