[Click] click + gre tunnel

[Erik VandeKieft]

Hi,

I still can't seem to successfully send packets to a gre tunnel using
click.  Here's the tcpdump output of gre packets sent via the regular
linux kernel, versus with click. To do the first test, I simply added a
route to gradlab.ucsd.edu with device "farm" (the gre tunnel device), and
pinged gradlab:

btw, (128.54.16.16 == other end of gre tunnel)

----
# tcpdump -vvv -i eth0 dst 128.54.16.16
tcpdump: listening on eth0
18:07:14.769438 wamp.ucsd.edu > teleport.ucsd.edu: gre 10.0.1.1 > gradlab.ucsd.edu: icmp: echo request (DF) (ttl 64, id 0, len 84) (DF) (ttl 255, id 0, len 108)
18:07:15.782063 wamp.ucsd.edu > teleport.ucsd.edu: gre 10.0.1.1 > gradlab.ucsd.edu: icmp: echo request (DF) (ttl 64, id 0, len 84) (DF) (ttl 255, id 0, len 108)
18:07:16.782135 wamp.ucsd.edu > teleport.ucsd.edu: gre 10.0.1.1 > gradlab.ucsd.edu: icmp: echo request (DF) (ttl 64, id 0, len 84) (DF) (ttl 255, id 0, len 108)
---

Note the nice output that shows you what the encapsulated gre packet's
source and dst are.

Now, here's the same tcpdump using the following click command:

# click -e 'ICMPPingSource(10.0.1.1, 132.239.55.107) -> ToDevice(farm)'

btw, (132.239.55.107 == gradlab.ucsd.edu)

---
18:13:23.753185 wamp.ucsd.edu > teleport.ucsd.edu: gre gre-proto-0x0003 (DF) (ttl 255, id 0, len 52)
18:13:24.763224 wamp.ucsd.edu > teleport.ucsd.edu: gre gre-proto-0x0003 (DF) (ttl 255, id 0, len 52)
18:13:25.763296 wamp.ucsd.edu > teleport.ucsd.edu: gre gre-proto-0x0003 (DF) (ttl 255, id 0, len 52)
---

Note that the encapsulated gre packet seems different. Anyone have any
clue as to what might be going on?

Thanks,
--Erik Vandekieft


On Thu, 8 Jul 2004, Eddie Kohler wrote:

> Erik,
>
> Could you use 'tcpdump' to compare Click's packets with packets
> generated by some other program?
>
> E
>
> On Jul 8, 2004, at 3:00 PM, Erik VandeKieft wrote:
>
> > Hi, I'm running click in userland and trying to send and receive
> > packets
> > to a gre tunnel interface. The name of my tunnel interface is "farm". I
> > created a simple FromDevice(farm) element, and that seems to recieve
> > packets just fine. But the ToDevice(farm) element doesn't seem to work
> > correctly... I can see the gre packets going out on eth0, but they get
> > dropped somewhere at the other end of the tunnel-- could it be that
> > they
> > are formatted improperly?
> >
> > In short, is my usage expected to work? Do I have to do anything
> > special
> > to send IP packets to a gre tunnel?
> >
> > Thanks very much,
> > --Erik Vandekieft
> >
> >
> > _______________________________________________
> > click mailing list
> > click at amsterdam.lcs.mit.edu
> > https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>
>