FTP non-standard port

Discussion in 'Networking Issues' started by jaxxone, Jun 11, 2008.

  1. jaxxone

    jaxxone Addicted to LI Member

    Hi guys,

    I need some help, read this please.

    Equip's on network:

    Router - Linksys RV042 - firmware v1.3.10 (wan - 86.55.14.xxx)
    Iomega Home Network External HDD with FTP service attached to a lan port at Linksys router.

    Router config:

    In service management i've added a new service FTP2 with tcp port 2021.
    Created a forward rule for FTP2 to (iomega hdd)

    Iomega config:

    Listening on port 2021

    Results for trying to connect from outside to my iomega hdd ftp service:

    telnet 86.55.14.xxx 2021
    220 IOMEGA NET Disk FTP Server ready.

    This means that I am connectet to my IOMEGA ftp service from outside network.

    If I try from inside my network to connect to ftp://86.55.14.xxx:2021 ... it works.
    I can access the ftp from inside.

    From outside... I cannot access the IOMEGA FTP with any kind of software or windows explorer. I only can see that I'm connect if I do a cmd telnet command to the ip that forwards connections on 2021 port to my inside network IOMEGA FTP hdd.

    In my opinion something is not well configured or my router still has any other firmware problems.

    Anyone ... please feel free to add a opinion.
    Thank you,
  2. fyellin

    fyellin LI Guru Member

    FTP is always a big pain when it comes to firewalls and NAT. You may want to read up about FTP on Wikipedia.

    What happens if you forward both 2020 and 2021 to the iomega hdd? This may be sufficient to fix your problem. It depends on the particular way that NAT works on your router.

    In general, you shouldn't be using ftp, period, unless you're inside a secure network or you're accessing "public" data. It's a highly insecure protocol. Use scp or sftp instead.
  3. jaxxone

    jaxxone Addicted to LI Member

    As I told you, I can test this connection only with command prompt.
    I mean when I access via command prompt ... i can connect.
    I can use dir command but I cannot get something or put something.

  4. fyellin

    fyellin LI Guru Member

    I think you misunderstood my comment (or I misunderstood yours).

    Try telling your router to forward both ports. Even though FTP communication in your configuration is initiated on 2021, the actual data transfer happens on 2020. Forwarding both ports may allow you to ftp from the outside.

    Don't try "telnet <myrouter> 2020" from outside. There's no one there unless ftp is active.

    I actually don't have great confidence that this will work. But it's an easy thing to try.
  5. jaxxone

    jaxxone Addicted to LI Member

    I don't have 2 ports to set in my ftp hdd.
    So witch ports to forward... except 2021?
  6. fyellin

    fyellin LI Guru Member

    The data port is always the server port minus 1. 2020 in my message above wasn't intended to be a random number.

    Like I said, this probably won't work. But it's worth a try.
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