ISP question [ was traceroute , pls ]

[David A. Bandel]

On Fri, Oct 17, 2008 at 11:15 AM, vu pham <vu at sivell.com> wrote:
> David A. Bandel wrote:
>>
>> On Fri, Oct 17, 2008 at 9:10 AM, vu pham <vu at sivell.com> wrote:
>>>
>>> Are the ISPs supposed to let the traceroute packets get thru ?
>>>
>>> I am on a server, which cannot traceroute all the way to the destination,
>>> and I still be able to make the smtp connection to the destination.
>>>
>>> So I guess I cannot conclude about connections based only on the
>>> traceroute
>>> path, is that correct ?
>>
>> Correct.  There are a _lot_ of clueless admins out there.  Most are
>> Windoze admins, but some find their way into other networking
>> positions.  They are under the mistaken illusion that if they block
>> things like ping (ICMP) and traceroute (in UNIX, udp, in Windoze
>> ICMP),
>
> You make me remember the first time I learned about how traceroute works by
> using the TTL field. That's a nice invention, isn't it ?
> It tooks almost 20 years since the Internet came into being to have such a
> simple but very useful tool like that.

???  Um, I know I used traceroute (and tcpdump) and others some 30
years ago (we're talking UNIX systems now, not DOS -- Windows didn't
even exist then).  That is less than 20 years after the arpanet (now
known as the Internet) came into being.  And ttl's are as old as the
IPv4 protocol (actually older).

Ciao,

David A. Bandel
-- 
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto