How can I prevent the warning No xauth data; using fake authentication data for X11 forwarding?

Every time I initiate an ssh connection from my Mac to a Linux (Debian) I do get this warning:

No xauth data; using fake authentication data for X11 forwarding.

This also happens for tools that are using ssh, like git or mercurial.

I just want to make a local change to my system in order to prevent this from appearing.

Note: I do have X11 server (XQuartz 2.7.3 (xorg-server 1.12.4)) on my Mac OS X (10.8.1) and it is working properly, I can successfully start clock locally or remotely.

Solution 1:

None of the posted solutions worked for me. My client (desktop) system is running macOS 10.12.5 (Sierra). I added -v to the options for the ssh command and it told me,

debug1: No xauth program.

which means it doesn't have a correct path to the xauth program. (On this version of macOS the path to xauth is nonstandard.) The solution was to add this line to /etc/ssh/ssh_config (may be /etc/ssh/config in some setups) or in ~/.ssh/config (if you don't have admin rights):

XAuthLocation /opt/X11/bin/xauth

Now the warning message is gone.

Solution 2:

Found the cause, my ~/.ssh/config was incomplete, you need both:

Host *
    ForwardAgent yes
    ForwardX11 yes

My mistake was that I included only the ForwardX11 option.

Solution 3:

Letting Ubuntu bash on Windows 10 run ssh -X to get a GUI environment on a remote server

• First

Install all the following. On Window, install Xming. On Ubuntu bash, use sudo apt install to install ssh xauth xorg.

sudo apt install ssh xauth xorg

• Second

Go to the folder contains ssh_config file, mine is /etc/ssh.

• Third

Edit ssh_config as administrator(USE sudo). Inside ssh_config, remove the hash # in the lines ForwardAgent, ForwardX11, ForwardX11Trusted, and set the corresponding arguments to yes.

# /etc/ssh/ssh_config

Host *
    ForwardAgent yes
    ForwardX11 yes
    ForwardX11Trusted yes

• Forth

In ssh_config file, remove the front hash # before Port 22 and Protocol 2, and also append a new line at the end of the file to state the xauth file location, XauthLocation /usr/bin/xauth, remember write your own path of xauth file.

# /etc/ssh/ssh_config

#   IdentifyFile ...
    Port 22
    Protocol 2
#   Cipher 3des
#   ...
#   ...
    ...
    ...
    GSSAPIDelegateCredentials no
    XauthLocation /usr/bin/xauth

• Fifth

Now since we are done editing ssh_config file, save it when we leave the editor. Now go to folder ~ or $HOME, append export DISPLAY=localhost:0 to your .bashrc file and save it.

# ~/.bashrc
...
...
export DISPLAY=localhost:0

• Last

We are almost done. Restart your bash shell, open your Xming program and use ssh -X yourusername@yourhost. Then enjoy the GUI environment.

ssh -X yourusername@yourhost

The problem is also in Ubuntu subsystem on Windows, and the link is at

https://gist.github.com/DestinyOne/f236f71b9cdecd349507dfe90ebae776

Note: the linked text includes 2 typos (XauthLocaion instead of XauthLocation)