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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: mail service with no mx (was - Re: Computer systems blamed forfeeble hurricane response?)
Adam McKenna wrote: On Tue, Sep 13, 2005 at 04:31:05PM -0700, william(at)elan.net wrote:Telnet option negotiation is at Layer 7 after TCP connection has been established. Firewalls typically don't operate at this level (TCP session is Layer 4 if I remember right) and would refuse or reject (difference type of ICMP response) based solely on attempt to connect to certain ip or certain TCP/UDP port.Application layer firewalls have existed for at least 6 years. AAAAAAAAAAAGGGGGGGGGGHHHHHH! But the point is that you would still establish a TCP connection before a MTA, firewall, IPS, or whatever could know it was telnet! The FEMA address that started this whole thing was timing out. You can tell the difference between a telnet filter and something completely, silently blocking 25/tcp. CAN THIS DIE NOW? Pulllleeeeeese... -- Crist J. Clark [email protected] Globalstar Communications (408) 933-4387
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