[Click] Problems using Click

[Julián David Morillo Pozo]

Sorry, there was a mistake on the previous message: the IP address of the 
client machine is 10.0.0.1 and not 10.0.0.4. 

El Jueves, 3 de Febrero de 2005 16:21, Julián David Morillo Pozo escribió:
> Hello,
>
> We are trying to comunicate two machines using user level CLICK, but some
> strange things are happening. We are using two directly connected machines
> that have flat IP addresses (10.0.0.1/32 and 10.0.0.4/32) and that act both
> as a router and as a host. In order to allow this behaviour, we are using
> the KernelTun element and every packet generated by the machine is routed
> to the tun0 device created by this element (this is the only route we have
> in the kernel forwarding table of both machines).
>
> We are able to ping from one machine to the other but we can not establish
> a tcp connection (ftp, ssh) between them. By executing tcpdump on the
> client machine (10.0.0.4/32) we have got the following:
>
> tcpdump: listening on eth0
> 15:34:58.439506 10.0.0.1.35284 > 10.0.0.4.ftp: S 2110020349:2110020349(0)
> win 6024 <mss 2008,sackOK,timestamp 590699432 0,nop,wscale 1> (DF)
> 15:34:58.439774 10.0.0.4.ftp > 10.0.0.1.35284: S 2069372027:2069372027(0)
> ack 2110020350 win 5988 <mss 2008,sackOK,timestamp 619677506
> 590699432,nop,wscale 0> (DF)
> 15:34:58.439948 10.0.0.1.35284 > 10.0.0.4.ftp: R 2110020350:2110020350(0)
> win 0 (DF)
>
> And at the same time, click shows the following error messages:
>
> LinearIPLookup: no gw for 3205393
> LinearIPLookup: no gw for 4215393
>
> Everything works fine if we use regular kernel forwarding in the client
> machine (10.0.0.4/32).
>
> The CLICK configuration we are using in the client is the following (in the
> server, the configuration is the same, just changing IP addresses):
>
> ============================================================
> // Shared IP input path and routing table
> _xorp_ip :: Strip(14)
>     -> CheckIPHeader(INTERFACES 10.0.0.1/32)
>     -> _xorp_rt :: LinearIPLookup(10.0.0.1/32 1, 10.0.0.4/32 0);
>
> elementclass FixChecksums {
>     input -> SetIPChecksum
>           -> ipc :: IPClassifier(tcp, udp, -)
>           -> SetTCPChecksum
>           -> output;
>     ipc[1] -> SetUDPChecksum -> output;
>     ipc[2] -> output
> }
>
> tun :: KernelTun(172.16.0.1/24) -> Paint(0) -> _xorp_rt;
>
>
> // ARP responses are copied to each ARPQuerier and the host.
> _xorp_arpt :: Tee(2);
>
> // Input and output paths for eth0
> _xorp_c0 :: Classifier(12/0806 20/0001, 12/0806 20/0002, 12/0800, -);
> FromDevice(eth0) -> _xorp_c0;
> _xorp_out0 :: Queue(200) -> _xorp_to_device0 :: ToDevice(eth0);
> _xorp_c0[0] -> _xorp_ar0 :: ARPResponder(10.0.0.1 00:0C:6E:F2:9B:6E) ->
> _xorp_out0;
> _xorp_arpq0 :: ARPQuerier(10.0.0.1, 00:0C:6E:F2:9B:6E) -> _xorp_out0;
> _xorp_c0[1] -> _xorp_arpt;
> _xorp_arpt[0] -> [1]_xorp_arpq0;
> _xorp_c0[2] -> Paint(1) -> _xorp_ip;
> _xorp_c0[3] -> Print("eth0 non-IP") -> Discard;
>
> // Local delivery
> _xorp_arpt[1] -> Discard;
> _xorp_rt[1] -> Discard;
>
> // Forwarding path for eth0
> _xorp_rt[0] -> DropBroadcasts -> _xorp_sw0 :: PaintSwitch();
> _xorp_gio0 :: IPGWOptions(10.0.0.1)
>     -> FixIPSrc(10.0.0.1)
>     -> _xorp_dt0 :: DecIPTTL
>     -> _xorp_fr0 :: IPFragmenter(1500)
>     -> [0]_xorp_arpq0;
>
> _xorp_sw0[0] -> StoreIPAddress(10.0.0.1,12) -> FixChecksums -> _xorp_fr0;
> _xorp_sw0[1] -> _xorp_cp0 :: Tee(2) -> ICMPError(10.0.0.1, redirect, host)
> -> _xorp_rt;
> _xorp_cp0[1] -> _xorp_gio0
> _xorp_dt0[1] -> ICMPError(10.0.0.1, timeexceeded) -> _xorp_rt;
> _xorp_fr0[1] -> ICMPError(10.0.0.1, unreachable, needfrag) -> _xorp_rt;
> _xorp_gio0[1] -> ICMPError(10.0.0.1, parameterproblem) -> _xorp_rt;
> ==============================================================
>
> Does anybody know what is the problem?
>
> Cheers,

-- 
=============================================
Julián David Morillo Pozo
PhD Student - Computer Networking Group
Department of Computer Architecture   (DAC)
Polytechnical University of Catalonia (UPC)
Phone: +34-934017182   Fax: +34-934017055
URL: http://people.ac.upc.edu/jmorillo
=============================================