Date: Wed, 10 Sep 2008 21:43:55 -0500 From: Kevin Kinsey <kdk@daleco.biz> To: Andrew Falanga <af300wsm@gmail.com> Cc: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: mail server DNS configuration questions Message-ID: <48C885EB.7070302@daleco.biz> In-Reply-To: <48C87517.8020908@gmail.com> References: <200809061928.28539.af300wsm@gmail.com> <20080907034834.GB37461@shepherd> <48C87517.8020908@gmail.com>
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Andrew Falanga wrote: > Clients in the churches private network cannot send mail using this > server, though they can receive mail from it (POP). The church has a > private network, PN1, and the mail server sits at a church members house > because he has a static IP address; let's call that PN2. The router at > his house is setup to forward traffic over port 25, and the POP port, to > this server. Also, just to further clarify, the Internet separates > these two Private Networks. However, this may not be entirely true as I > think about it because at both locations, the ISP is CableOne using > cable broadband. So, though technically part of the Internet, the > traffic shouldn't leave the CableOne domain. Also, of interest, is that > another of our pastors uses CableOne at home and is unable to send > e-mail using the churches server from home. However, from a coffee shop > in town, that our pastors frequent, they are able to send mail. It is > my understanding that this coffee shop does not use CableOne. > > So, just to make sure everyone's got it, the mail server sits in PN2. > While diagnosing this, I connect to the server (using Putty) from a > machine in PN1, using either a mail client or telnet I'm unable to make > a connection to the mail server over port 25. Using tcpdump during this > putty session I do not even see the SYN packets for the start of the > connection from the machines in PN1. This is only when connecting to > port 25. Obviously, I can connect to the server because I'm using > putty. Also, I can see the SYN packets for the start of the connection > when this same machine in PN1 attempts to connect to port 80. The > problem seems to be when trying to connect over port 25. For some > reason, the packets aren't being delivered to that address > (72.24.34.252). This happens if I try to telnet to > mail.whitneybaptist.org or telnet to 72.24.34.252 on port 25. The > packets aren't being delivered. They're being sent somewhere else, or > lost in digital purgatory. > > Now, from home (my home) let's call this PN3, I can send/receive mail > using the church e-mail server. I, however, don't use CableOne. Are > there routers that route traffic based on port number? It's almost as > if traffic, that originates within the CableOne domain and travels > through, but not outside, the CableOne domain, doesn't get routed to the > correct address when it's destined for port 25. So a common thread is that traffic on the ISP's net isn't going out via yourserver.com:25 --- would seem to indicate port blocking, which is quite common for port 25. Tried 587 or some weird alternate? Kevin Kinsey -- If the odds are a million to one against something occurring, chances are 50-50 it will.
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