[Click] Problems using Click
Julián David Morillo Pozo
jmorillo at ac.upc.edu
Fri Feb 4 05:50:20 EST 2005
Hello,
John, thanks for yout answer but I think it is not my solution (probably I
didn't explain very well my problem). Briefly, my question is: Why, with my
configuration shown in the previous mail, I can ping from one machine to the
other but I cannot open a TCP connection?
I guess that my kernel receives packets destined for it (a ping works
correctly).
The tcpdump log (shown in the previous mail) shows that my client machine
(10.0.0.1) generates a SYN packet, then a SYN-ACK reply arrives from the
server machine (10.0.0.4). The problem comes then, when my client machine
generates a RESET packet instead of an ACK packet, and the connection is not
established.
If I don't use linux on my client everything works fine, so I guess that the
problem is with CLICK. But pings works, and UDP too. Even T CP works ok until
the third step of the 3-WayHandshake, when my client sents a RESET.
Any idea?? (I'm completely lost)
Thanks a lot
El Jueves, 3 de Febrero de 2005 19:46, John Bicket escribió:
> I think I understand that you want click to route packets from eth0
> on the 10.0.0.X network.
>
> Your probably want to do this instead of what you configuration does:
>
> 1. run ifconfig eth0 up, but don't give it an ip address. Otherwise linux
> will handle the routing and arp, and if I understand you correctly you
> want userlevel click to handle this stuff.
> 2. Use tun :: KernelTun(10.0.0.1/24). Linux will add the route to
> 10.0.0.X through the tun0 brought up by kerneltun. Now you have
> to send packets destined to 10.0.0.1 in your configuration to the "tun"
> element, otherwise the kernel will not get them.
>
> --john
>
> Juli?n David Morillo Pozo [jmorillo at ac.upc.edu] wrote:
> >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, Juli?n David Morillo Pozo escribi?:
> >> 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,
> >
> >--
> >=============================================
> >Juli?n 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
> >=============================================
> >
> >
> >_______________________________________________
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> >click at amsterdam.lcs.mit.edu
> >https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>
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--
=============================================
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
=============================================
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