traceroute using tcp on a specific port?

My home linux system had a whole lot of connectivity problems a few days 
ago. One of the problems was that all of a sudden people who tried to 
connect to my sendmail server got connection refused. 

I knew that the problem was not related to anything going on at my end. My 
server was not getting any packets (seen via ethereal). I called my ISP 
(RCN) who insisted that they were not blocking my port 25. (I pay extra 
for them to not block me.)

And yet when I went over to another machine outside of RCN and tried to 
telnet to my 25 I would in fact get connection refused.

To add to the confusion, a friend told me that a backbone had just gone 
bankrupt and the whole world was trying to figure out how to reroute 
packets. The result was that packets were taking more hops to get where 
they wanted to go.

So what I am looking for is a tool that can tell me just where along the 
path my packets were getting refused. How can I tell if it was RCN or 
someone even before it got to RCN.

(The problem clearup up after >5 hours.)

Thanks guys.

-- 
Time flies like the wind. Fruit flies like a banana. Stranger things have  .0.
happened but none stranger than this. Does your driver's license say Organ ..0
Donor?Black holes are where God divided by zero. Listen to me! We are all- 000
individuals! What if this weren't a hypothetical question?
steveo at syslang.net
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