How to Debug SSH Client Session in linux

Sometimes it is necessary to view debug messages to troubleshoot any SSH
connection issues.

 pass -v (lowercase v) option to the ssh as shown below to
view the ssh debug messages.


Example without SSH client debug message:

localhost$ ssh -l jsmith remotehost.example.com
warning: Connecting to remotehost.example.com failed:
No address associated to the name

Example with SSH client debug message:
locaclhost$ ssh -v -l jsmith remotehost.example.com
debug:
SshConfig/sshconfig.c:2838/ssh2_parse_config_ext:
Metaconfig parsing stopped at line 3.

debug:
SshConfig/sshconfig.c:637/ssh_config_set_param_verbose:
Setting variable ‘VerboseMode’ to ‘FALSE’.

debug:
SshConfig/sshconfig.c:3130/ssh_config_read_file_ext:
Read 17 params from config file.
debug: Ssh2/ssh2.c:1707/main: User config file not
found, using defaults. (Looked for
‘/home/jsmith/.ssh2/ssh2_config’)
debug: Connecting to remotehost.example.com, port 22...
(SOCKS not used)
warning: Connecting to remotehost.example.com failed:
No address associated to the name