ICMP being blocked by ATT

[Derek Zeanah]

>I was chatting with our internet provider who gets their feed from ATT,
>he notified me that they are blocking all ICMP protocols.
>By gosh by golly, I can't ping, tracert, nothing...  Is this new?
>Shall I complain?
>

I'm not sure you'll be able to do much.

You remember that last batch of Microsoft RPC worms?  There was another 
that followed it up, supposedly designed to "fix" the vulnerability, but 
that's questionable.  Anyway, this follow-up (called Welchia, among 
other things) has a nasty habit of causing pingstorms.  It wants to ping 
the entire IP address space sequentially, from what I can tell, looking 
for new hosts to try and infect.

I've seen one infected machine consume so much bandwidth that no-one 
else could access the T1, going through each IP sequentially...

Anyway, my ISP (Megapath) shut off ICMP traffic temporarily to make the 
network usable gain; now tracert's coming from outside the network 
behave as advertized, but anything initiated within the network gets 
stomped.  AT&T is probably doing the same, and I doubt they'll change 
anything until Welchia runs its course.