different proxys at different locations

[Amedee Van Gasse]

Hello,

I use my netbook at 3 different locations:

HOME: no proxy

WORK: ISA proxy http://a.b.c.d:8080/ with Basic Auth, asks for user_work +
pass_work, can be set with $http_proxy and $https_proxy.

SCHOOL: ISA proxy http://e.f.g.h:8080/ with NTLM Auth, asks for
domain_school\user_school + pass_school, requires cntlm to work,
$http_proxy has to be set to http://127.0.0.1:3128/


Currently I have to remember and change the proxy settings all the time.
Sometimes I even have to reboot because the proxy changes don't "take".

I would like a solution where I set only one proxy, something like
http://127.0.0.1:3128/, and Ubuntu figures out what to do, wherever I am.

Any pointers would be helpful, because Google was not my friend this morning.

-- 
Amedee