Layer Four Traceroute (lft)
31 03 2007I’m a big fan of tcptraceroute. It’s a very useful tool for network administrators (in addition to the traditional traceroute). I had tcptraceroute installed on my MacBook via MacPorts, but later it stopped working (”libnet_write failed? Attempted to write 40 bytes, only wrote -1″ error message) due to libnet compatibility problem. I couldn’t find a fix to that problem so I searched for a similar tool to replace tcptraceroute for my MacBook. I found lft on Google. Apparently lft is more flexible and advanced than tcptraceroute. What makes lft even better than tcptraceroute? lft is included in Fedora Extras! Since I use Fedora Core for my servers, this is much better than having to use third-party repository (e.g. dries, dag, etc.)
Normally, I use the following syntax for lft:
lft -C -z -n -E -S google.com
Since this problem was posted ages and ages ago, it is no longer directly relevant but FWIW a google search has lead me here, so…
libnet_write failed? Attempted to write 40 bytes, only wrote -1″ error message
seems just to be a firewall thing!!
I did a quick
#/etc/rc.d/init/iptables stop
And the trace ran fine, restarted iptables, fiddled around with the settings and all was well.
JFWIW