X11 Forwarding

[Wesley Witt <wesw@xxxxxxxxxxxxxx>]

I am trying to get X11 forwarding working and it appears that the right support is in libssh, but the docs are not clear as to how to make it work.

Below is the code and the resulting libssh log. Xclock does execute but I do not see the UI display on the remote computer. There is a note in the docs about seeting the DISPLAY variable, but I'm not sure where to set it. I tried using ssh_channel_request_env but that does not work. I'm not even sure if this is the issue. Any help would be appreciated.

If I start an SSH session using "ssh -X", set the DISPLAY variable in the shell and then start xclock it works as expected. This is what I want to accomplish with libssh.


m_channel = ssh_channel_new(m_session);
ssh_channel_open_session(m_channel);
ssh_channel_request_x11(m_channel, 1, NULL, NULL, 0);
ssh_channel_request_exec(m_channel, "xclock");
ssh_channel x11_channel = ssh_channel_accept_x11(m_channel, 3000);


[2017/02/11 09:23:47.520517, 2] ssh_connect:  libssh 0.7.2 (c) 2003-2014 Aris Adamantiadis, Andreas Schneider, and libssh contributors. Distributed under the LGPL, please refer to COPYING file for information about your rights, using threading threads_noop
[2017/02/11 09:23:47.528022, 2] ssh_socket_connect:  Nonblocking connection socket: 472
[2017/02/11 09:23:47.528022, 2] ssh_connect:  Socket connecting, now waiting for the callbacks to work
[2017/02/11 09:23:47.528522, 1] socket_callback_connected:  Socket connection callback: 1 (0)
[2017/02/11 09:23:47.535528, 1] ssh_client_connection_callback:  SSH server banner: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
[2017/02/11 09:23:47.535528, 1] ssh_analyze_banner:  Analyzing banner: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
[2017/02/11 09:23:47.535528, 1] ssh_analyze_banner:  We are talking to an OpenSSH client version: 7.2 (70200)
[2017/02/11 09:23:47.638095, 2] ssh_packet_dh_reply:  Received SSH_KEXDH_REPLY
[2017/02/11 09:23:47.641598, 2] ssh_client_curve25519_reply:  SSH_MSG_NEWKEYS sent
[2017/02/11 09:23:47.641598, 2] ssh_packet_newkeys:  Received SSH_MSG_NEWKEYS
[2017/02/11 09:23:47.643599, 2] ssh_packet_newkeys:  Signature verified and valid
[2017/02/11 09:23:47.691131, 2] channel_open:  Creating a channel 43 with 64000 window and 32768 max packet
[2017/02/11 09:23:47.788195, 2] ssh_packet_global_request:  Received SSH_MSG_GLOBAL_REQUEST packet
[2017/02/11 09:23:47.788696, 2] ssh_packet_global_request:  UNKNOWN SSH_MSG_GLOBAL_REQUEST hostkeys-00@xxxxxxxxxxx 0
[2017/02/11 09:23:47.788696, 1] ssh_packet_process:  Couldn't do anything with packet type 80
[2017/02/11 09:23:47.788696, 2] ssh_packet_channel_open_conf:  Received a CHANNEL_OPEN_CONFIRMATION for channel 43:0
[2017/02/11 09:23:47.788696, 2] ssh_packet_channel_open_conf:  Remote window : 0, maxpacket : 32768
[2017/02/11 09:23:47.789196, 2] channel_request:  Channel request x11-req success
[2017/02/11 09:23:47.789696, 2] channel_rcv_change_window:  Adding 2097152 bytes to channel (43:0) (from 0 bytes)
[2017/02/11 09:23:47.789696, 2] channel_request:  Channel request exec success