From Comcast Cable, at my home in Atlanta, I can ping 10.10.1.1....
which is pong'ed from a private client network hanging somewhere off of
Insight Broadband's network in the North Central part of the US. Why on
god's green earth do network operators allow such nonsense as this?
-Jim P.
Traceroute -I 10.10.1.1 produces the following:
traceroute to 10.10.1.1 (10.10.1.1), 30 hops max, 38 byte packets
1 10.238.10.1 (10.238.10.1) 29.089 ms 25.387 ms 28.574 ms
2 66.56.22.66 (66.56.22.66) 30.923 ms 31.305 ms 33.142 ms
3 66.56.22.70 (66.56.22.70) 35.945 ms 35.874 ms 36.832 ms
4 c-66-56-23-38.atl.client2.attbi.com (66.56.23.38) 34.740 ms 35.041
ms 37.537 ms
5 12.118.184.41 (12.118.184.41) 41.967 ms 45.584 ms 43.997 ms
6 gbr2-p70.attga.ip.att.net (12.123.21.6) 44.988 ms 44.706 ms
43.033 ms
7 tbr2-p013602.attga.ip.att.net (12.122.12.37) 49.353 ms 44.010 ms
45.244 ms
8 12.122.10.138 (12.122.10.138) 62.244 ms 62.269 ms 62.148 ms
9 gbr1-p40.sl9mo.ip.att.net (12.122.11.114) 60.922 ms 67.005 ms
60.264 ms
10 gar1-p360.sl9mo.ip.att.net (12.123.24.209) 59.572 ms 64.013 ms
60.198 ms
11 12-220-0-69.client.insightBB.com (12.220.0.69) 77.000 ms 76.050
ms 77.926 ms
12 12-220-7-198.client.insightBB.com (12.220.7.198) 95.437 ms 80.068
ms 84.076 ms
13 10.10.1.1 (10.10.1.1) 93.612 ms 97.280 ms 192.994 ms
Jim Popovitch wrote:
From Comcast Cable, at my home in Atlanta, I can ping 10.10.1.1....
which is pong'ed from a private client network hanging somewhere off of
Insight Broadband's network in the North Central part of the US. Why on
god's green earth do network operators allow such nonsense as this?
FWIW, I get the same result from Comcast residential coax
service from Santa Clara, CA using a plain ol' *nix UDP
traceroute. (This is not ICMP specific.)
raceroute 10.10.1.1
traceroute to 10.10.1.1 (10.10.1.1), 64 hops max, 44 byte packets
[snip my internal net]
3 12.244.25.145 (12.244.25.145) 17.315 ms 17.378 ms 17.492 ms
4 12.244.67.17 (12.244.67.17) 33.548 ms 23.702 ms 13.066 ms
5 12.244.72.206 (12.244.72.206) 21.554 ms 18.118 ms 18.589 ms
6 gbr2-p50.sffca.ip.att.net (12.123.13.62) 23.677 ms 31.973 ms 18.647 ms
7 tbr1-p012702.sffca.ip.att.net (12.122.11.69) 24.447 ms 19.266 ms 19.036 ms
8 tbr1-cl2.sl9mo.ip.att.net (12.122.10.41) 73.801 ms 66.745 ms 71.541 ms
9 gbr2-p10.sl9mo.ip.att.net (12.122.11.102) 68.524 ms 62.157 ms 66.172 ms
10 gar1-p370.sl9mo.ip.att.net (12.123.24.213) 68.568 ms 65.325 ms 62.455 ms
11 12-220-0-69.client.insightBB.com (12.220.0.69) 93.072 ms 98.102 ms 91.132 ms
12 12-220-7-198.client.insightBB.com (12.220.7.198) 88.131 ms 83.943 ms 85.713 ms
13 10.10.1.1 (10.10.1.1) 159.507 ms 101.956 ms 95.575 ms
I know that Comcast (formerly AT&T BB) uses the 10-net internally
on their transit networks so they can't just blackhole the stuff.
Insight's ISP is AT&T (now Comcast?). Looking quickly at the AT&T
looking glass, Insight appears to not have its own AS. RFC1918
successfully crossing between ASes would be a Very Bad Thing.
However, it looks like it is completely within AT&T here. Not a
Good Thing, but not the end of the world. For all I know,
10.10.1.1 might be AT&T equipment using their internal 10-net.
Jim Popovitch wrote:
From Comcast Cable, at my home in Atlanta, I can ping 10.10.1.1....
which is pong'ed from a private client network hanging somewhere off of
Insight Broadband's network in the North Central part of the US. Why on
god's green earth do network operators allow such nonsense as this?
FWIW, I get the same result from Comcast residential coax
service from Santa Clara, CA using a plain ol' *nix UDP
traceroute. (This is not ICMP specific.)
Interesting to see who does and doesn't apply bogon filters to their BGP sessions.
From a Verio space, the packets do not make it past a default-free router. Good filtering.
From AT&T space, the trace goes all the way to InsightBB, no filtering of prefixes.
It appears XO does not filter, but that whomever they try to hand the traffic off to in Dallas does filter.
Comcast (New England) seems to have some level of filtering, but has a default route loop between Lowell, MA and Needham, MA in their traces. Nice.
Appears level3.net filters properly.
The presence of the route did provide a nice set of data to see whose networks are implementing filtering.
AT&T normally rejects bogons such as RFC1918, urpf-detected forgeries
from customers,
traffic pointed at internal network routers, etc. However, AT&T's
network does support MPLS,
so if InsightBB is part of the Comcast cloud, it may be that this
_looks_ like the public internet
but is really an MPLS private network cloud that happens to use
similar addresses and
only reaches the Internet through gateways, in spite of being carried
on much of the same hardware.
Disclaimer: As a Comcast stockholder, I probably should know their architecture
and whether or not InsightBB is part of their company,
but all I really know about it is that cable companies have a history
of doing funky things,
particularly with NAT, which is one of many reasons I use DSL at home
instead of cable modems. And this posting is strictly my private
speculation, not my employer's.
Bill Stewart