John McGowan wrote:
> Kernel 2.6.13: TCP (libnet?)
>
> Broken libnet?
>
> KERNEL: [email protected]
> LIBNET 1.1 (c) 1998 - 2004 Mike D. Schiffman <[email protected]>
>
> I don't like spam. I track spamvertized sites. Many only respond to TCP
> packets sent to port 80. I need a TCP traceroute (traceroute using TCP/SYN
> packets).
>
> I have four such programmes.
>
> 1: Hping in traceroute mode.
> Poor. If it hits a router which does not respond, it just sits
> and waits.
> 2: LFT
> OK.
> a: Does not work in Fedora Core2 - without patching.
> The source code expects a header of zero bytes in the
> pcap output of zero bytes (hard coded in the source).
> My captures have a "linux cooked capture" header of sixteen bytes.
> Changing an offset from zero to sixteen gets it to work.
> b: Requires traffic on the interface.
> It seems it gets into a loop and awaits some traffic.
> It examines it - if it is data it expects it uses it.
> If it is other data from other programmes accessing the 'net
> it does nothing with it.
> In both those cases it moves on and starts over.
> What if there is no traffic? Unless there is something for it
> either to use or ignore, it seems to hang. To get it to work
> I have to, say, read the NY Times online while running it.
> (I believe the traceproto site mentions doing something to
> get around the timeout problem)
> Output is OK - but I don't really like it.
> 3: Tcptraceroute
> I have used this since kernel 2.2 through 2.4
> (older version with older version of libnet) and
> 2.6.5, 2.6.7, 2.6.9, 2.6.10, 2.6.11, 2.6.12
> It was my favourite until I got traceproto.
> 4: Traceproto
> I have used this in kernels 2.4,
> 2.6.5, 2.6.7, 2.6.9, 2.6.10, 2.6.11, 2.6.12
> Good.
>
>
> In kernel 2.6.13: [patching 2.1.12 with the patch file]
>
> Standard "traceroute" works.
> LFT works.
> HPING works (also in traceroute mode).
> tcptraceroute fails.
> traceproto (tcp or udp mode) fails.
>
> How do they fail?
>
> A TCPDUMP shows that they do send out the packets.
> I do get back ICMP "time exceeded" error messages.
> They no longer recognize them.
>
> Something that had never changed before has now changed
> and has broken traceproto and tcptraceroute.
[netdev CC'ed]
Could you provide tcpdump dumps and your .config file please?
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