RE: traceroute-like tool for UDP or TCP packet

["David Gillett" <gillettdavid () fhda edu>]

> > Linux uses UDP packets to traceroute, not ICMP packets like 
> > windows does.
>
> Not really.... an ICMP packet is a type of UDP packet. 

  Nope.  ICMP and UDP are different protocols on top of IP.

> Basicly traceroute works by sending a series of ICMP ECHO 
> requests with increacing TTLs (time to live - how many hops 
> the packet can travel before it dies and aPacket
> Timeout error is sent).

  What kind of packet traceroute sends depends on what the
author chose to use.  The two most common are UDP echo-request
and ICMP echo-request, because the target host should reply
with a UDP echo or ICMP echo (respectively) instead of the 
ICMP time-exceeded which intermediate routers will send when
TTL expires.

> A ping is also just a ICMP ECHO message, just with
> a defualt TTL, rather than a series of increasing TTLs.

  ICMP echo-request, actually; ICMP echo is the answer coming
back.

David Gillett



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