Asn

This Sunday I was looking at global routing table dump and found AS1 announcing some very weird prefixes.

AS1 i.e Autonomous System Number 1 belongs to Level3 but as far as I know they are not actively using it. They use AS3356 globally (along with Global Crossing’s AS3549). I noticed quite a few prefixes of a Brazil based telecom provider - Netvip Telecomunicaes being announced by AS1. 

Some of entries in global routing table belonging to AS1 (as picked from BGP table dump of route-views archive):

Sometimes we see interesting IP’s in traceroute & they confuse lot of people.

I have seen this topic in discussion twice on NANOG and once on Linux Delhi user group. 

OK - let’s pick an example: 

anurag:~ anurag$ traceroute 71.89.140.11
traceroute to 71.89.140.11 (71.89.140.11), 64 hops max, 52 byte packets
1 router (10.10.0.1) 1.176 ms 0.993 ms 0.941 ms
2 117.220.160.1 (117.220.160.1) 20.626 ms 29.101 ms 19.216 ms
3 218.248.169.122 (218.248.169.122) 23.983 ms 43.850 ms 45.057 ms
4 115.114.89.21.static-mumbai.vsnl.net.in (115.114.89.21) 118.094 ms 81.447 ms 66.838 ms
5 172.31.16.193 (172.31.16.193) 115.979 ms 90.947 ms 90.491 ms
6 ix-4-2.tcore1.cxr-chennai.as6453.net (180.87.36.9) 95.778 ms 98.601 ms 98.920 ms
7 if-5-2.tcore1.svw-singapore.as6453.net (180.87.12.53) 321.174 ms
if-3-3.tcore2.cxr-chennai.as6453.net (180.87.36.6) 331.386 ms 326.671 ms
8 if-6-2.tcore2.svw-singapore.as6453.net (180.87.37.14) 317.442 ms
if-2-2.tcore2.svw-singapore.as6453.net (180.87.12.2) 334.647 ms 339.289 ms
9 if-7-2.tcore2.lvw-losangeles.as6453.net (180.87.15.26) 318.003 ms 328.334 ms 309.234 ms
10 if-2-2.tcore1.lvw-losangeles.as6453.net (66.110.59.1) 306.500 ms 326.194 ms 341.537 ms
11 66.110.59.66 (66.110.59.66) 315.431 ms 330.417 ms 308.372 ms
12 dls-bb1-link.telia.net (213.155.136.40) 354.768 ms 344.360 ms 357.050 ms
13 chi-bb1-link.telia.net (80.91.248.208) 352.479 ms 358.751 ms 359.987 ms
14 cco-ic-156108-chi-bb1.c.telia.net (213.248.89.46) 367.467 ms 370.482 ms 377.280 ms
15 bbr01aldlmi-bue-4.aldl.mi.charter.com (96.34.0.98) 387.269 ms 385.362 ms 365.694 ms
16 crr02aldlmi-bue-2.aldl.mi.charter.com (96.34.2.11) 375.275 ms 375.356 ms 371.621 ms
17 dtr02grhvmi-tge-0-1-0-0.grhv.mi.charter.com (96.34.34.83) 383.539 ms 371.817 ms 383.804 ms
18 dtr02whthmi-tge-0-1-0-0.whth.mi.charter.com (96.34.34.85) 384.400 ms 391.197 ms 393.340 ms
19 dtr02ldngmi-tge-0-1-0-0.ldng.mi.charter.com (96.34.34.87) 371.192 ms 375.679 ms 378.457 ms
20 acr01mnplmi-tge-0-0-0-3.mnpl.mi.charter.com (96.34.40.75) 364.824 ms 385.534 ms 374.401 ms
21 * *^C
anurag:~ anurag$

Let’s try pinging IP on 14th hop (which is with a major backbone Telia) - 213.248.89.46

Sleepless night. Reading more about Quagga and it’s options.

In meanwhile a quick 5min script to enable domain to BGP/IP/ASN mapping. This script is using basic dig command (for finding IP address) and Team Cymru whois service for IP to ASN/block mapping.

#!/bin/bash  
\# Script for domain name to IP/ASN/BGP block mapping  
hostname=v4.whois.cymru.com  
IP=$(dig $1 a +short)  
whois -h $hostname " -c -p $IP"

Yeah just 3 line script! Less code = more power! 

Whenever I see a new unknown IP range, it gets hard to find exact source of that IP within command shell. Recently, I found a very interesting source of that information from Team Cymru.

I figured out (with a friend’s help) that using their whois server - v4.whois.cymru.com one can actually grab limited information as required. 

E.g

anurag@laptop:~$ whois -h v4.whois.cymru.com "  -v 8.8.8.8"
AS      | IP               | BGP Prefix          | CC | Registry | Allocated  | AS Name

15169   | 8.8.8.8          | 8.8.8.0/24          | US | arin     | 1992-12-01 | GOOGLE - Google Inc.

As we can see -v gives all possible information. All I needed was AS number, AS Name, BGP Prefix, Country code - this gives enough information for an IP address. Thus command turns out to be with -c & -p.