7.04: X11 remote display problem

Wed Nov 21 17:09:15 UTC 2007

On Wednesday 21 November 2007, you wrote:
> Il giorno mer, 21/11/2007 alle 14.55 +0000, bill purvis ha scritto:
> > Smoot,
> > unless I'm mis-reading it this is turned on:
> >
> > /etc/ssh/ssh_config (on felix)
> >
> > #   ForwardX11 no
>
> You misread :) If the value commented out in the default configuration
> file is (normally) the default value.
> Try using option -X (Capital X) to ssh, this will enable ssh port
> forwarding for X even if is disabled in /etc/ssh_config. Of course, it
> still must be enabled in sshd_conf on the server machine.
>
> If this does not work, try running ssh in debug mode and see what it
> says...
Leo,
You didn't read all my message - I had already tried the -X option with no
joy. And all the config files I've dealt with don't follow your convention -
they usually provide ability to switch by simply commenting or uncommenting
the line.

However,
I did try changing the ssh_config file to read

ForwardX11  yes

but still no joy.
I have tried using the debug option (-vv)
and got the following. Note that the IP addresses are private to my network
so I don't think this reveals much to any outside hackers.

Felix is the laptop, bohuslav is the server...

---------------------------------------------------------------------
felix ~$ ssh -vv bohuslav
OpenSSH_4.3p2 Debian-8ubuntu1, OpenSSL 0.9.8c 05 Sep 2006
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to bohuslav [192.168.0.154] port 22.
debug1: Connection established.
debug1: identity file /home/bill/.ssh/identity type -1
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug2: key_type_from_name: unknown key type '-----END'
debug1: identity file /home/bill/.ssh/id_rsa type 1
debug1: identity file /home/bill/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_3.9p1
debug1: match: OpenSSH_3.9p1 pat OpenSSH_3.*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3p2 Debian-8ubuntu1
debug2: fd 3 setting O_NONBLOCK
debug1: An invalid name was supplied
Configuration file does not specify default realm

debug1: An invalid name was supplied
A parameter was malformed
Validation error

debug1: An invalid name was supplied
Configuration file does not specify default realm

debug1: An invalid name was supplied
A parameter was malformed
Validation error

debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: 
diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: 
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: 
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: 
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: 
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: 
diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: 
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: 
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc at lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: 
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: 
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
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
debug2: dh_gen_key: priv key bits set: 124/256
debug2: bits set: 510/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'bohuslav' is known and matches the RSA host key.
debug1: Found key in /home/bill/.ssh/known_hosts:2
debug2: bits set: 519/1024
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/bill/.ssh/identity ((nil))
debug2: key: /home/bill/.ssh/id_rsa (0x80054500)
debug2: key: /home/bill/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: /home/bill/.ssh/identity
debug1: Offering public key: /home/bill/.ssh/id_rsa
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 149
debug2: input_userauth_pk_ok: fp 
<rsa key edited out, just in case>8-)
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: x11_get_proto: /usr/bin/X11/xauth  list :0.0 2>/dev/null
debug1: Requesting X11 forwarding with authentication spoofing.
debug2: channel 0: request x11-req confirm 0
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 0
debug1: Sending environment.
debug1: Sending env LC_COLLATE = C
debug2: channel 0: request env confirm 0
debug1: Sending env LANG = C
debug2: channel 0: request env confirm 0
debug2: channel 0: request shell confirm 0
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 131072
Last login: Wed Nov 21 16:46:31 2007 from felix.billp.org
bohuslav bill$ emacs &
[1] 20965
bohuslav bill$ emacs: Cannot connect to X server felix:0.0.
Check the DISPLAY environment variable or use `-d'.
Also use the `xhost' program to verify that it is set to permit
connections from your machine.

[1]+  Exit 1                  /usr/bin/emacs -geometry 80x48 -font 9x15
bohuslav bill$ 

That all looks OK to me apart from a couple of validation errors, which
don't convey much to me, and of course the failure of emacs to make a
connection. Since there is no indication of what the invalid name was 
I can't see how to fix that. 

Bill
-- 
+---------------------------------------+
| Bill Purvis, Amateur Mathematician    |
|  email: bil at beeb.net                  |
|  http://bil.members.beeb.net          |
+---------------------------------------+