I would try a tracert command and see if you can spot a node where the break
is occuring. It definetely sounds like a routing issue.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED]
Sent: Thursday, August 12, 1999 5:19 PM
To: [EMAIL PROTECTED]
Subject: Re: [IMail Forum] service denial: no server access
The machine in question was completely blocked from going beyond the router,
even by pinging IP addresses. On the internal LAN, however, it worked
great.
Similiarly, any outside system could ping into the LAN, but not to that one
system. Since this was all with IP addresses, DNS isn't the issue. I think
the comment someone else made is along the right path: some sort of block
along the upstream path. But how, and how do I detect it? Or, if it is a
DoS attack, how do I detect that?
Ben
In a message dated 8/11/99 6:44:04 PM Pacific Daylight Time,
[EMAIL PROTECTED] writes:
<<
>So what could block this one machine and no other? The problem appeared
suddenly, lasted for a couple of hours, and then disappeared without
explanation. I'm not sure what to look for or how to investigate it.
Were you trying to use names or IP numbers? If it was names, since this
machine is your DNS server, something could have happened with the name
resolution system. If even the IP numbers were not working, then I would go
after something at the gateway. There is even an "esoteric" possibility
that
has just been advertised: there is a new DoS attack using ICMP packets to
corrupt routing tables. AFAIK, it only affects Win9x and Win2k, but who
knows?
HTH,
Rubens
>>
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