Windows DatabaseebooksStatistical Information

LLE10017 : Howto quickly debug an ssh connection on a commandline

Symptom:

The SSH connection does not work or seems to work strange

Cause:

This can have lots of causes, most of them are configuration issues

Solution:

Try connection with verbose mode active. You will be able to see all the actions taken by the protocol.

ssh -v -X -l username remotehost

The following output is an example:

debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to 192.168.123.3 [192.168.123.3] port 22.
debug1: Connection established.
debug1: identity file /home/wpeeters/.ssh/identity type -1
debug1: identity file /home/wpeeters/.ssh/id_rsa type -1
debug1: identity file /home/wpeeters/.ssh/id_dsa type -1
debug1: Remote protocol version 1.99, remote software version OpenSSH_4.1
debug1: match: OpenSSH_4.1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.2p1 Debian-7ubuntu3.1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '192.168.123.3' is known and matches the RSA host key.
debug1: Found key in /home/wpeeters/.ssh/known_hosts:3
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: /home/wpeeters/.ssh/identity
debug1: Trying private key: /home/wpeeters/.ssh/id_rsa
debug1: Trying private key: /home/wpeeters/.ssh/id_dsa
debug1: Next authentication method: keyboard-interactive
Password:
debug1: Authentication succeeded (keyboard-interactive).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Requesting X11 forwarding with authentication spoofing.
debug1: Sending environment.
debug1: Sending env LANG = de_DE.UTF-8
Last login: Fri Oct 26 18:22:21 2007 from 192.168.123.22

This connection has X11 forwarding active. You can see it in the output by searchgin "Requesting X11 forwarding with authentication spoofing". 


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