Invalid MIT-MAGIC-COOKIE-1 in Arch Linux

I recently reinstalled my Arch Linux desktop onto a brand spankin’ new solid-state hard drive. I’ve been extremely happy with the performance, but I was having problems with X11 forwarding over SSH.

aorth@dspace:~$ meld
Invalid MIT-MAGIC-COOKIE-1 key/usr/lib/pymodules/python2.6/gtk-2.0/gtk/ GtkWarning: could not open display
  warnings.warn(str(e), _gtk.Warning)
/usr/bin/meld:111: GtkWarning: gtk_icon_theme_get_for_screen: assertion `GDK_IS_SCREEN (screen)' failed
Traceback (most recent call last):
  File "/usr/bin/meld", line 111, in 
AttributeError: 'NoneType' object has no attribute 'append_search_path'

It was happening on both CentOS and Debian remotes, both of which were working when SSH’d from other machines.

Install xauth!

The solution is to install xauth!

sudo pacman -Sy xorg-xauth

I guess I’m just used to Debian-based distros where xauth was preinstalled (or alongside Xorg, I suppose?). Anyways, that’s what’s up. 😛