Good old WEP-bugs from 2006 in 2009.

As everybody should know, WEP is a dead protocol - but right now I need it. On the run on an island where only a WEP-AP is available.

But Gnomes Network-Manager failed after key definition, it tries to establish a connection several times and finally kills itself.

Read the man-pages - they do suggest for a manual definition using 's:passphrase', which only lead to error messages ...

A simple solution can be found on the net, and so I gave it a try:

'sudo iwconfig eth0 essid name_of_AP key restricted your_wep_key_here'
(w/o the 's:'-string-stuff) [1]

Now try to fire it up and grab an address via DHCP:
'sudo dhclient3'

It works for me - and the Network-Manager stills says 'no connection available'. Looks like the short word 'restricted' is the key for salvation.

Helper pages:
[1] https://bugs.launchpad.net/debian/+source/netcfg/+bug/20247

P.S. Just written after connecting via WEP using this hint.