lft :: Layer Four Trace

Colin pointed out a useful utility called lft in response to a question on IIU. lft looks like a useful alternative traceroute application as it claims to have the ability to identify stateful inspection firewalls and other useful information.

What I found immediately attractive was the -A option which displays the AS numbers of addresses along the path and also the -N which looks up and displays the network names.

e.g.

# lft -S -A  www.yahoo.com

TTL  LFT trace to f1.us.www.vip.ird.yahoo.com (87.248.113.14):80/tcp
 ...
 ...
 3   [AS35272] lns3.net.imagine.ie (87.232.0.26) 27.3ms
 4   [AS35272] ve5.core.net.imagine.ie (87.232.0.129) 9.0ms
 5   [AS35272] ge0-0.border1.net.imagine.ie (87.232.0.1) 8.6ms
 6   [AS3257] ge-2-0-0-207.dub20.ip.tiscali.net (213.200.67.145) 13.8ms
 7   [AS3257] yahoo-overture-gw2.dub20.ip.tiscali.net (213.200.67.202) 13.9ms
 8   [AS34010] ge-1-4.bas-b1.ird.yahoo.com (87.248.101.13) 10.9ms
 9   [AS34010] [target] f1.us.www.vip.ird.yahoo.com (87.248.113.14):80 12.6ms

and

# lft -S -N www.heanet.ie

TTL  LFT trace to www.heanet.ie (193.1.219.79):80/tcp
 ...
 ...
 3   [87-RIPE/IMAGINE-IRL] lns1.net.imagine.ie (87.232.0.24) 24.0ms
 4   [87-RIPE/IMAGINE-IRL] ve5.core.net.imagine.ie (87.232.0.129) 22.3ms
 5   [87-RIPE/IMAGINE-IRL] ge0-0.border1.net.imagine.ie (87.232.0.1) 60.6ms
 6   [RIPE-CBLK/IE-INEX-IPV4-PI-NETBLK1] gige6-1-cr1-cwt.hea.net (193.242.111.16) 8.7ms
 7   [RIPE-CBLK/HEANET-EXT] gige6-1-ar1-cwt.hea.net (193.1.195.177) 45.4ms
 8   [RIPE-CBLK/HEANET-EXT] blanch-sr1-po1.services.hea.net (193.1.195.139) 25.6ms
 9   [RIPE-CBLK/HEANET-LAN] [target] www.heanet.ie (193.1.219.79):80 9.4ms