ftpd behind NAT router - Minix

This is a discussion on ftpd behind NAT router - Minix ; Has anyone got "ftpd" working on minix connected to the outside world through a router? I found interesting link: http://www.allaboutjake.com/network/linksys/ftp that puts some light on the subject. But minix ftpd manual does not describe any config files. Karel...

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Thread: ftpd behind NAT router

  1. ftpd behind NAT router

    Has anyone got "ftpd" working on minix connected to the outside world
    through
    a router?
    I found interesting link:
    http://www.allaboutjake.com/network/linksys/ftp that puts some light
    on the subject.
    But minix ftpd manual does not describe any config files.

    Karel


  2. Re: ftpd behind NAT router

    On Jan 29, 11:27 am, "karel" wrote:
    > Has anyone got "ftpd" working on minix connected to the outside world
    > through
    > a router?
    > I found interesting link:http://www.allaboutjake.com/network/linksys/ftpthat puts some light
    > on the subject.
    > But minix ftpd manual does not describe any config files.
    >
    > Karel


    Hello,
    normally ftp servers have some direct connection or translation so
    have access to all ports. You use the passive
    command from the ftp client.

    ftp uses port 21 for control and 20 for data. When you issue a DIR
    command, ftp client send where it is listening, but if you are behind
    a NAT or firewall, the information that ftp client sends is IP and
    ports of internal machine. Some firewalls does the work of translating
    the IP and port, creates a LAT (Local Address Translation Table) and
    this ftp proxy uses the table to translate the commands. The firewall
    that does not translate commands, need to use passive mode, so ftp use
    the same control and data port, the problem is that you can not send
    out of band commands, like control C to cancel the data stream.

    I saw that when you like to have an ftp server, you configure mapping
    an internal IP to external IP so it can use all available ports. NAT
    concept is to translate both IP and ports, but the common
    implementation I saw is to use a fix IP and translate ports, so the
    software in the NAT router hava a simple table. More complex
    implementations, like PIX firewalls, translates both IP and ports.

    I did some work for using NAT in minix 2.0 so I used it at home with a
    small network and a single dial up line. In that work I only translate
    ports, using the fix IP assigned by the dial up ISP.

    For minix ftpd you only need that it handle the PASV o passive
    command. You can test if from any ftp client.

    Regards,
    Claudio.



  3. Re: ftpd behind NAT router

    I have now minix ftpd working behind a router. I had to disable
    the NAT translation by using DMZ (Demilitarized Zone) feature
    of the router. This way all traffic from outside is directed to
    the minix machine and ftpd works fine.
    Karel


  4. Re: ftpd behind NAT router

    On Feb 1, 4:52 pm, "karel" wrote:
    > I have now minix ftpd working behind a router. I had to disable
    > the NAT translation by using DMZ (Demilitarized Zone) feature
    > of the router. This way all traffic from outside is directed to
    > the minix machine and ftpd works fine.
    > Karel


    Karel, thank you for yours tests and comments.

    Regards,
    Claudio.


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