Forward X11 failed: Network error: Connection refused

Question

I have a VPS which OS is CentOS6.3. I want to run startx via PuTTY and Xming.

But, it produces this error:

PuTTY X11 proxy: unable to connect to forwarded X server: Network error: Connection refused

The whole condition:

Using username "root".
Authenticating with public key "rsa-key-20150906" from agent
Last login: Thu Jan 21 13:53:40 2016 from 222.222.150.82
[root@mairo ~]# xhost +
PuTTY X11 proxy: unable to connect to forwarded X server: Network error: Connection refused
xhost:  unable to open display "localhost:10.0"
[root@mairo ~]# echo $DISPLAY
localhost:10.0
[root@mairo ~]# gedit
PuTTY X11 proxy: unable to connect to forwarded X server: Network error: Connection refused
(gedit:6287): Gtk-WARNING **: cannot open display: localhost:10.0
[root@mairo ~]#

And here is the Xming log:

Welcome to the Xming X Server
Vendor: Colin Harrison
Release: 6.9.0.31
FreeType2: 2.3.4
Contact: http://sourceforge.net/forum/?group_id=156984

Xming :10 -multiwindow -clipboard 

XdmcpRegisterConnection: newAddress 192.168.139.1
winAdjustVideoModeShadowGDI - Using Windows display depth of 32 bits per pixel
winAllocateFBShadowGDI - Creating DIB with width: 1366 height: 768 depth: 32
winInitVisualsShadowGDI - Masks 00ff0000 0000ff00 000000ff BPRGB 8 d 24 bpp 32
glWinInitVisuals:1596: glWinInitVisuals
glWinInitVisualConfigs:1503: glWinInitVisualConfigs glWinSetVisualConfigs:1581: glWinSetVisualConfigs
init_visuals:1055: init_visuals
null screen fn ReparentWindow
null screen fn RestackWindow
InitQueue - Calling pthread_mutex_init
InitQueue - pthread_mutex_init returned
InitQueue - Calling pthread_cond_init
InitQueue - pthread_cond_init returned
winInitMultiWindowWM - Hello
winInitMultiWindowWM - Calling pthread_mutex_lock ()
winMultiWindowXMsgProc - Hello
winMultiWindowXMsgProc - Calling pthread_mutex_lock ()
glWinScreenProbe:1390: glWinScreenProbe
fixup_visuals:1303: fixup_visuals
init_screen_visuals:1336: init_screen_visuals
(--) 5 mouse buttons found
(--) Setting autorepeat to delay=500, rate=31
(--) winConfigKeyboard - Layout: "00000804" (00000804) 
(EE) Keyboardlayout "Chinese (Simplified) - US Keyboard" (00000804) is unknown
Could not init font path element D:\Program Files (x86)\Xming/fonts/misc/, removing from list!
Could not init font path element D:\Program Files (x86)\Xming/fonts/TTF/, removing from list!
Could not init font path element D:\Program Files (x86)\Xming/fonts/Type1/, removing from list!
Could not init font path element D:\Program Files (x86)\Xming/fonts/75dpi/, removing from list!
Could not init font path element D:\Program Files (x86)\Xming/fonts/100dpi/, removing from list!
Could not init font path element C:\Program Files\Xming\fonts\dejavu, removing from list!
Could not init font path element C:\Program Files\Xming\fonts\cyrillic, removing from list!
Could not init font path element C:\WINDOWS\Fonts, removing from list!
winInitMultiWindowWM - pthread_mutex_lock () returned.
winInitMultiWindowWM - pthread_mutex_unlock () returned.
winInitMultiWindowWM - DISPLAY=127.0.0.1:10.0
winMultiWindowXMsgProc - pthread_mutex_lock () returned.
winMultiWindowXMsgProc - pthread_mutex_unlock () returned.
winMultiWindowXMsgProc - DISPLAY=127.0.0.1:10.0
winProcEstablishConnection - Hello
winInitClipboard ()
winProcEstablishConnection - winInitClipboard returned.
winClipboardProc - Hello
DetectUnicodeSupport - Windows Vista
winClipboardProc - DISPLAY=127.0.0.1:10.0
winInitMultiWindowWM - XOpenDisplay () returned and successfully opened the display.
winMultiWindowXMsgProc - XOpenDisplay () returned and successfully opened the display.
winClipboardProc - XOpenDisplay () returned and successfully opened the display.

Here is my sshd_config on VPS:

#   $OpenBSD: sshd_config,v 1.80 2008/07/02 02:24:18 djm Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/local/bin:/bin:/usr/bin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options change a
# default value.

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# Disable legacy (protocol version 1) support in the server for new
# installations. In future the default will change to require explicit
# activation of protocol 1
Protocol 2

# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024

# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile .ssh/authorized_keys
#AuthorizedKeysCommand none
#AuthorizedKeysCommandRunAs nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
PasswordAuthentication yes

# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes
ChallengeResponseAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
#KerberosUseKuserok yes

# GSSAPI options
#GSSAPIAuthentication no
GSSAPIAuthentication yes
#GSSAPICleanupCredentials yes
GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no

# Set this to 'yes' to enable PAM authentication, account processing, 
# and session processing. If this is enabled, PAM authentication will 
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
#UsePAM no
UsePAM yes

# Accept locale-related environment variables
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS

#AllowAgentForwarding yes
#AllowTcpForwarding yes
GatewayPorts yes
#X11Forwarding no
X11Forwarding yes
#X11DisplayOffset 10
X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#ShowPatchLevel no
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none

# no default banner path
#Banner none

# override default of no subsystems
Subsystem   sftp    /usr/libexec/openssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#   X11Forwarding no
#   AllowTcpForwarding no
#   ForceCommand cvs server

And I have enabled the X11 forwarding

What's causing the error given above?

---

New added details

According to @lilydjwg answer, I have filled the "X display location" And then tried again, but it's still wrong:

Using username "root".
Authenticating with public key "rsa-key-20150906" from agent
Last login: Thu Jan 21 22:24:57 2016 from 222.222.150.82
[root@mairo ~]# echo $DISPLAY
localhost:10.0
[root@mairo ~]# gedit
process 6968: D-Bus library appears to be incorrectly set up; failed to read machine uuid: Failed to open"/var/lib/dbus/machine-id": No such file or directory
See the manual page for dbus-uuidgen to correct this issue.
  D-Bus not built with -rdynamic so unable to print a backtrace
Aborted
[root@mairo ~]#

Answer 1

Other answers are outdated, or incomplete, or simply don't work.

You need to also specify an X-11 server on the host machine to handle the launch of GUId programs. If the client is a Windows machine install Xming. If the client is a Linux machine install XQuartz.

Now suppose this is Windows connecting to Linux. In order to be able to launch X11 programs as well over putty do the following:

- Launch XMing on Windows client
- Launch Putty
    * Fill in basic options as you know in session category
    * Connection -> SSH -> X11
        -> Enable X11 forwarding
        -> X display location = :0.0
        -> MIT-Magic-Cookie-1
        -> X authority file for local display = point to the Xming.exe executable

Of course the ssh server should have permitted Desktop Sharing "Allow other user to view your desktop".

MobaXterm and other complete remote desktop programs work too.

Answer 2

PuTTY can't find where your X server is, because you didn't tell it. (ssh on Linux doesn't have this problem because it runs under X so it just uses that one.) Fill in the blank box after "X display location" with your Xming server's address.

Alternatively, try MobaXterm. It has an X server builtin.

Answer 3

The D-Bus error can be fixed with dbus-launch :

dbus-launch command

Answer 4

fill in the "X display location" did not work for me. but install MobaXterm did the job.

Answer 5

I had the same problem, but it's solved now. Finally, Putty does work with Cigwin-X, and Xming is not an obligatory app for MS-Windows X-server.

Nowadays it's xlaunch, who controls the run of X-window. Certainly, xlaunch.exe must be installed in Cigwin. When run in interactive mode it asks for "extra settings". You should add "-listen tcp" to additional param field, since Cigwin-X does not listen TCP by default.

In order to not repeat these steps, you may save settings to the file. And run xlaunch.exe via its shortcut with modified CLI inside. Something like

C:\cygwin64\bin\xlaunch.exe -run C:\cygwin64\config.xlaunch