CODEWITHSUNDEEP
bashshellsshterminate
user2001669
user2001669

Reputation: 41

SSH Session Started from Here Doc Does Not Exit Properly

SSH session doesn't terminate and give the tty back when executed inside a here document. Below is the code snippet that's inside my shell script:

ssh -t -t root@$HOST_ADDRESS <<TERM_STRING
cd /tmp/
sleep 2
exit 0
TERM_STRING

After the command exit 0, the terminal is stuck and doesn't give me the tty back. Is there something I am doing wrong?

This is what I get after trying the SSH with -v flag

[root ~]# ssh -v -t -t 10.215.194.38
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to 10.215.194.38 [10.215.194.38] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type 1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: loaded 3 keys
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.2
debug1: match: OpenSSH_5.2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
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 '10.215.194.38' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:5
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,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure.  Minor code may provide more information
Unknown code krb5 195

debug1: Unspecified GSS failure.  Minor code may provide more information
Unknown code krb5 195

debug1: Unspecified GSS failure.  Minor code may provide more information
Unknown code krb5 195

debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Offering public key: /root/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_US

Last login: Wed Jan 23 14:02:39 2013 from 10.134.232.195
[[email protected] ~]# exit 0

The only thing that stands out for me is the line:

debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure.  Minor code may provide more information
Unknown code krb5 195

Upvotes: 4

Views: 912

Answers (1)

Alessandro
Alessandro

Reputation: 2533

Just tried on my server and it works (Ubuntu connecting to Centos 6).

Try disabling GSSAPI in the server configuration (comment it out and restart sshd, you won't lose the connection)

If the connection hangs try this:

  1. Look at the PID of the ssh process
  2. Have a look under /proc/ for hints
  3. Look lsof and see if ssh keeps anything open
  4. Check that the client is not configured to automatically setup port forwarding

Regards Alessandro

Upvotes: 0

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