Symptom
This single error message appears only if the ssh session is started from apple shell/terminal. Through putty or linux, this is not observed
Conditions
At the first, the issue observed on C9410 with IOS-XE 16.6.2.
Similar issue observes on C2960X/C2960XR with IOS 15.2(4)E5, but it does not observe using 15.2(4)E4.
C9410#sh ip ssh
SSH Enabled - version 1.99
Authentication methods:publickey,keyboard-interactive,password
Authentication Publickey Algorithms:x509v3-ssh-rsa,ssh-rsa
Hostkey Algorithms:x509v3-ssh-rsa,ssh-rsa
Encryption Algorithms:aes128-ctr,aes192-ctr,aes256-ctr
MAC Algorithms:hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-sha1-96
KEX Algorithms:diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
Authentication timeout: 120 secs; Authentication retries: 3
Minimum expected Diffie Hellman key size : 2048 bits
IOS Keys in SECSH format(ssh-rsa, base64 encoded): TP-self-signed-3661210606
%SSH: Failed to encode IOS ASN.1 to SECSH format
C9410#
C9410#
C9410#
C9410#
C9410#
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
*Jan 2 12:47:37.459: SSH-1: Not an SSH session connection block
C9410#
