artificial latency for a network interface

[Andreas Schuldei <andreas@schuldei.org>]

to simulate a sattelite link, I need to add a latency to a
network connection. 

What is the easiest and best way to do that?

I wanted to do that using two tun devices. 
I had hoped to have a routing like this:

 <-> eth0 <-> tun0 <-> userspace, waiting queue <-> tun1 <-> eth1

I need to do it this way and not with iptables help, because it
needs to work also on 2.2.x kernels.

Now I started experimenting with the tun0 interfaces and got
problems: till now I have not succeeded to get a tun0 interface
up. the example code (br_select.c) in the package (as found for
example on sourceforge) looks fishy and does not work too well. 
is it correct that only one /dev/tun file is necessary, but
/dev/tun0 and tun1 are opend for reading and writing?

I also did not manage to point any routes at tun0 or tun1. thoes
interfaces do not show up in the /proc/net/dev either.

only the module is loaded.

I seem to miss something. who has used those devices before and
got them working and could help me debug this?