"ssh -X ... " & Firefox

Поключаемся к удаленному хосту с "пробросом Х-ов"

local $ ssh -X user@host

При попытке запустить firefox получаем приблизительно такое:

remote $ firefox
The program 'firefox' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAccess (attempt to access private resource denied)'.
  (Details: serial 515 error_code 10 request_code 18 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)
remote $

Решается запуском firefox с ключом -no-remote

remote $ firefox -no-remote