[ale] Cablemodem shows in my traceroutes?

Robert L. Harris Robert.L.Harris at rdlg.net
Thu Feb 27 11:08:45 EST 2003



I can get in and out fine, traceroutes are just slow some days and I'd
never seen it before (or not noticed).  It's got a short name of
"cablemodem" as I've put it in /etc/hosts just to speed up lookups.


Thus spake Drag0n (dragon at atlantacon.org):

> 	It is common for frame providers to route traffic across their internal
> network using assigned private numbers. A cablemodem is in a way, a
> hybid ATM frame relay network. What looks like is happening is some
> admin of the network is either cut and pasted the wrong host name into
> the dns table or they are just using a simple name to refer to the core
> cablemodem router. If everything works as its supposed to, (you can get
> out and data can get in) then there is nothing to worry about. I get a
> similar situation from home, but am able to access my home systems
> remotely so no routing problems there.
> 
>  1  * * *  (I drop all icmp trafic aimed at my firewall, internal or
> external)
>  2  10.238.252.1 (10.238.252.1)  7.257 ms  9.202 ms  11.586 ms
>  3  c-66-56-66-2.atl.client2.attbi.com (66.56.66.2)  7.950 ms  11.592
> ms  8.365 ms
>  4  c-66-56-23-38.atl.client2.attbi.com (66.56.23.38)  8.265 ms  10.729
> ms  8.158 ms
>  5  c-66-56-22-146.atl.client2.attbi.com (66.56.22.146)  8.186 ms 
> 23.566 ms  9.122 ms
> 
> Drag0n
> dragon at atlantacon.org
> 
> "Robert L. Harris" wrote:
> > 
> > I'm trying to debug some IPv6 and just ran a traceroute from behind my
> > firewall:
> > 
> > {0}:/usr/src/kernel>traceroute www.kame.net
> > traceroute to apple.kame.net (203.178.141.220), 30 hops max, 38 byte
> > packets
> >  1  wally (192.168.0.1)  0.249 ms  0.154 ms  0.130 ms
> >  2  cablemodem (10.2.0.1)  31.877 ms  9.824 ms  66.160 ms
> >  3  209.186.118.17 (209.186.118.17)  11.221 ms  11.911 ms  9.951 ms
> >  4  172.26.96.2 (172.26.96.2)  13.143 ms  9.803 ms  15.492 ms
> >  5  65.90.64.5 (65.90.64.5)  13.588 ms  12.239 ms  12.465 ms
> >  6  P5-0.c0.atln.broadwing.net (216.140.12.41)  12.650 ms  12.825 ms 12.056 ms
> >  7  p3-0.c0.wash.broadwing.net (216.140.8.109)  22.946 ms  24.353 ms 23.576 ms
> > .
> > .
> > .
> > 
> > umm, this is odd as the external interface of my firewall (wally) has a
> > valid IP (24.216.225.11)...
> > 
> > From my firewall:
> > 
> > raceroute to apple.kame.net (203.178.141.220), 30 hops max, 38 byte
> > packets
> >  1  cablemodem (10.2.0.1)  77.861 ms  20.864 ms  8.453 ms
> >  2  209.186.118.17 (209.186.118.17)  24.057 ms  39.684 ms  9.449 ms
> >  3  172.26.96.2 (172.26.96.2)  12.061 ms  10.679 ms  10.443 ms
> >  4  65.90.64.5 (65.90.64.5)  19.208 ms  11.687 ms  12.402 ms
> >  5  P5-0.c0.atln.broadwing.net (216.140.12.41)  19.451 ms  12.975 ms 16.829 ms
> >  6  p3-0.c0.wash.broadwing.net (216.140.8.109)  27.234 ms  29.734 ms 23.076 ms
> > 
> > Anyone else see this?  Is it normal?  I thought the cable modems acted
> > like a transparent bridge and wouldn't show in traceroutes, etc...
> > 
> > Robert
> > 
> > :wq!
> > ---------------------------------------------------------------------------
> > Robert L. Harris                     | PGP Key ID: E344DA3B
> >                                          @ x-hkp://pgp.mit.edu
> > DISCLAIMER:
> >       These are MY OPINIONS ALONE.  I speak for no-one else.
> > 
> > Diagnosis: witzelsucht
> > 
> > IPv6 = robert at ipv6.rdlg.net     http://ipv6.rdlg.net
> > IPv4 = robert at mail.rdlg.net     http://www.rdlg.net
> > 
> >   ------------------------------------------------------------------------
> >    Part 1.2Type: application/pgp-signature
> 
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:wq!
---------------------------------------------------------------------------
Robert L. Harris                     | PGP Key ID: E344DA3B
                                         @ x-hkp://pgp.mit.edu 
DISCLAIMER:
      These are MY OPINIONS ALONE.  I speak for no-one else.

Diagnosis: witzelsucht  	

IPv6 = robert at ipv6.rdlg.net	http://ipv6.rdlg.net
IPv4 = robert at mail.rdlg.net	http://www.rdlg.net

 PGP signature




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