[Click] New userlevel elements

[Mark Huang]

Hello all,

To support and encourage development of overlay networks on PlanetLab 
(http://www.planet-lab.org), I've developed a few new (mostly userlevel) 
Click elements that are immediately available from Click anonymous CVS 
(http://www.pdos.lcs.mit.edu/click/anoncvs.html). The new elements enable a 
PPTP ingress node and a userlevel NAT egress node to be easily constructed 
from standard Click elements, and leaves possibilities wide open for 
constructing the overlay itself.

The bulk of the elements are distributed in the "iias" package, which is 
distributed separately from the main Click distribution (check out 
click/packages in addition to click/release/one). Also in the "iias" package 
is an example configuration that I use to demonstrate a 
IP-in-GRE-in-UDP-in-IP overlay network on PlanetLab. The overlay network
is actually composed of two distinct networks: a PPP network that provides 
ingress into the overlay, and an IP-in-GRE-in-UDP-in-IP overlay network that 
is fully connected in a static routing scheme. One of the routers in the 
overlay network uses the new IPFlowRawSockets element to provide userlevel 
NAT egress for the entire overlay.

The Click ChangeLog contains more detailed information. Much of the PPTP code 
is derived from the open-source pppd and PoPToP projects, which is why the 
PPP elements are distributed separately from the main distribution.

Enjoy!

--Mark