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Thread: ZoneAlarms blocks access to FTP server

  1. #1
    Join Date
    Mar 2013

    Default ZoneAlarms blocks access to FTP server

    I just changed computers and installed ZoneAlarm Free I have an FTP server running which listens on port 526. My router is configured to pass incoming calls to the IP of my PC. When testing with one client for the first time on this PC, Zonealarm asked permission for the EFT server which I gave. The client could connect and everything seemed to work.

    However after the client disconnected he could not reconnect anymore. Only after restarting of the server could the client connect again. To see what the problem might be, I did the following.

    1) Client could connect one time, not the second time.
    2) I disabled the firewall, now the client could connect. My conclusion is that Zonealarm blocks the incoming traffic. It shouldn't because it should know that the EFTP server is listening to that port.
    3) I looked in the log and saw indeed that it had blocked that particular IP-address.
    4) When I add the incoming IP to the incoming zone and enable the firewall, the client can access the server again.

    Problem is that the client can login from any IP address, so the problem basically remains. Any idea why the first login to the server is accepted by ZoneAlarm, and the next attempts are blocked?

    I also tested with version and had the same result. On my old PC I had a much older version and did not have this problem. I also tested with 3 different ports and with 3 different persons. All have the same problem that they can only connect once.

  2. #2
    Join Date
    Nov 2004

    Default Re: ZoneAlarms blocks access to FTP server

    Sorry all users here and ZA support does not monitor this board (+ ZAfree offer no official support).

    The only thing I could suggest is to provide full details of the OS, Exact version of ZA (right click the ZA icon near the clock --> about --> Paste it in a reply) and the exact version of the FTP server used.

    ...and then hope that this is read by ZA staff and taken up by development.

    Alternatively, install ZA Extreme beta, test it and report the issue (if present) using the ZA beta feedback page. The message is received directly by ZA development team. (

    P.S. Obviously you have checked that all FTP server components have been granted all inbound/outbound permission (4 green checks) in ZA application control, right? Also checked by setting the application control to AUTO rather than MAX?
    Last edited by fax; March 31st, 2013 at 02:03 PM.

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  3. #3
    Join Date
    Mar 2013

    Default Re: ZoneAlarms blocks access to FTP server

    Yes, all 4 checks are there. And when the problem arose the application control was set to AUTO, I did change it to MAX with no result.

  4. #4
    Join Date
    Jun 2006
    The 3rd Coast - South Central Texas

    Smile Re: ZoneAlarms blocks access to FTP server

    Quote Originally Posted by YanYaj View Post
    Yes, all 4 checks are there. And when the problem arose the application control was set to AUTO, I did change it to MAX with no result.

    Welcome to the Zone Alarm User Forum..

    This Forum exist to allow Volunteer experienced Zone Alarm Users to help the Few Users who encounter a problem with ZoneAlarm and need to be guided in the right direction..

    It is Sometimes very Difficult to Diagnose and fix a Computer from halfway across the Country, or around the World,
    without All the Details about your computer it's Software that GURU Fax asked for that you failed to provide, without our ability to sit in front of your Computer monitor and see what's going on..

    The More information you post the more likely users here will be able to understand the issue and try to help.


    1.) I used "Serve-U FTP Server" and also a Mail Server for several Years on Windows XP with Zone Alarm Security Suite and Za Extreme security with no problems..

    2.) Also, I would not Rule out that It could even be an ISP issue. Sometime ISP's filter out ports at source (typically port 80 but also 20,21...)
    Last edited by GeorgeV; April 1st, 2013 at 11:55 AM.

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