Error: An established connection was aborted by the software in your host machine.

Posted on 2009-05-02
Last Modified: 2012-05-06
I have a VB (3.5) app that communicates via sockets on port 25 to an SMTP server. The 2 machines are on a company domain on the same LAN. I manually build MIME messages. I get the above error when sending large (approx 2 megabyte) messages. I do not get the error when sending smaller messages. Other notes:

- I am sending  from W2K3 SBS, IIS v 7. process to another W2K3 SBS machine.
- Also tried it on my network, from XP Pro, IIS 5.1 (?) to W2K3 SBS machine.
- The Idle timeout was set to 90 minutes. The error occurs after roughly 25 minutes.
- On my network I have Norton Antivirus on the XP machine. The client network (2003 to 2003) does not have antivirus. The NAV log showed no blocking activity during the time I got the errors.

What is causing this error? Is there a way to do a trace or something to get a better message?

Thank you.
Question by:MikeBroderick
    LVL 9

    Accepted Solution

    First thing i'd do is check the event log of the machine running the SMTP service. Maybe the error message there (if existent) is more helpful.

    Author Comment

    I did not find any errors that looked like SMTP errors. Sorry.
    LVL 9

    Assisted Solution


    Author Comment

    I found the problem. I turned off norton antivirus 2008 and it worked. I started connecting to the local machine's SMTP virtual server and it worked even with Norton turned on.

    I did not suspect Norton because there wasnt anything in their history log and sending small amounts of data worked. I had a similar problem a few years ago where very long-running (30 minute)  dos copy commands (copy c:aaa \\rmtshare\aaa) would fail when shorter-running commands would work. It turned out that in Norton's history file there was an entry saying the some kind of  "Raster-Blaster III-sounding"  Worm-trojan attack has been blocked every time my copy failed. I told Norton AV to ignore those attacks and my copys worked. New Norton versions have been put on and I havent had the problem again, so Norton apparently quietly fixed the problem. In Norton's defense, they said that the Microsoft copy (and xcopy) program, when used with network shares, woud do some kind of buffer overrun just like the worm did. OK.

     This looks just like a false-positive like before. I contacted norton and tried to find out why a) their history didnt show this false-positive and b) where are the exclusion lists. She was nice, but everything she told me was steps to install the latest version of NAV. Even after I explicitly told her that I did not want to install new software. I swear that I could have asked her "What is two and two equal" and her answer would be "install NAV 9".

    On you event response, I will look at it. I did not know you could set up logging. My target machine doesnt have a virtual smtp server in IIS. I am guessing it is because Exchange and ISA are also on that box. Besides, if norton was blocking on the client side, I think the log would have just seen the packets quit coming. Good info though.

    Thanks for your help.
    LVL 9

    Expert Comment

    Are you honestly trying to tell me that two and two no longer equals installing NAV9 ? Blasphemy.

    Glad you worked it out. ;)

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