On Sep 6, 2006, at 9:04 AM, Mike Walter wrote:
Recently with no changes to my network, I have been having problems connecting to certain websites and mail servers. I am always able to ping the sites and trace route without error. If I telnet to port 80 or port 25 it does not connect. If I login to my router and telnet sourcing my each of Internet Providers ports, I am able to get to the sites. I have talked with all the providers and none
Check a packet dump and see if your affected boxes are sending SWE (SYN with ECN enabled) instead of plain SYN packets. Some firewalls (at least default m0n0wall and older PIX) reject and dump ECN syn packets while allowing pure syns through. If your affected peer has you running through some weird filter that's dropping SWE packets, this would cause symptoms exactly as you're seeing - ping is fine, traceroute is fine, but TCP sessions never complete the handshake (as the receiving side never got the first SYN). - J