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asn_analyze

This set of tools intends to aid in identifying patterns of access by converting IP addresses into AS Numbers (http://en.wikipedia.org/wiki/AS_number). These are often way more informative than looking at individual IP prefixes. Especially since some large providers can have thousands of different IP prefixes. Included are two scripts

asn_ip_analysis.pl

This script expects just a list of IPs separated by a new line. It will give you a break down of IPs. For example you can use it to troubleshoot network issues ie. you notice large number of connections sitting in SYN-RECV state. You could run something like this

$ ss -ant | grep SYN-RECV | awk '{ print $5 }' | cut -f1 -d:  | perl asn_ip_analysis.pl 
Top  ASes

#          ASN
   1170 http://bgp.he.net/AS7657	 NZ = VODAFONE-NZ-NGN-AS Vodafone NZ Ltd.
      2 http://bgp.he.net/AS4771	 NZ = NZTELECOM Telecom New Zealand Ltd.\

Makes it pretty clear that something is happening with SYN-ACKs going to Vodafone.

You could also analyze your web logs to see where most of your customers are coming from e.g.

# cut -f1 -d" " access.log | perl /opt/asn/asn_ip_analysis.pl 
............................
You supplied 28646 IPs. Showing top 40 ASNs

# IPs            ASN
  331569    http://bgp.he.net/AS7922   US = COMCAST-7922 - Comcast Cable Communications
  290686     http://bgp.he.net/AS786   GB = JANET The JNT Association
  215274   http://bgp.he.net/AS15169   US = GOOGLE - Google Inc.
  134660    http://bgp.he.net/AS2856   GB = BT-UK-AS BTnet UK Regional network
  132031    http://bgp.he.net/AS7018   US = ATT-INTERNET4 - AT&T Services
   98942    http://bgp.he.net/AS1213   IE = HEANET HEAnet Limited
   98017     http://bgp.he.net/AS701   US = UUNET - MCI Communications Services
   87109    http://bgp.he.net/AS5089   GB = NTL Virgin Media Limited
   75678    http://bgp.he.net/AS3352   ES = TELEFONICA-DATA-ESPANA TELEFONICA DE ESPANA
.......

varnish_asn_breakdown.pl

This script is used to sample traffic going through varnish. This is intended for situations where your machines are multi-homed and you want to make sure links are used properly overused. It is similar to asn_ip_analysis however it does couple additional things

  • Uses payload information - bytes sent and sorts ASNs to which you send most traffic to
  • Shows a sample IP so you could look up routing policy if you desire
  • Shows which hop/router traffic is gonna go out of
  • It requires no arguments. It uses varnishncsa to get data