Strange issue while connecting using ssh / Need UDP ports open? - SSH

This is a discussion on Strange issue while connecting using ssh / Need UDP ports open? - SSH ; Hi, I'm experiencing a very strange problem while configuring my firewall on my linux box. I'm connecting to this linux box from my home computer running windows, using PuTTY. It seems in order to SSH to my linux box, from ...

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Thread: Strange issue while connecting using ssh / Need UDP ports open?

  1. Strange issue while connecting using ssh / Need UDP ports open?

    Hi,

    I'm experiencing a very strange problem while configuring my firewall
    on my linux box. I'm connecting to this linux box from my home
    computer running windows, using PuTTY. It seems in order to SSH to my
    linux box, from another computer, I need an open, UDP port range
    somewhere between 42000 to 42200 on my firewall. I tried tracing this
    down to a specific port, but it seems whatever this is, it changes
    every few minutes.

    If this UDP range isn't open, I cannot open a SSH connection to my
    linux box.

    I'm totally baffled here, ssh has always been available to me with
    just port 22. Could this be some type of back door into my system?
    (We have had "consultants" work on our server at some times).

    I don't see anything in the secure logs about these failures, and I
    tried running nmap on my server, and I can't see any open UDP ports in
    this range.

    Does anyone know what is going on here?


  2. Re: Strange issue while connecting using ssh / Need UDP ports open?

    woodswatcher@gmail.com writes:

    > Hi,
    >
    > I'm experiencing a very strange problem while configuring my firewall
    > on my linux box. I'm connecting to this linux box from my home
    > computer running windows, using PuTTY. It seems in order to SSH to my
    > linux box, from another computer, I need an open, UDP port range
    > somewhere between 42000 to 42200 on my firewall. I tried tracing this
    > down to a specific port, but it seems whatever this is, it changes
    > every few minutes.
    >
    > If this UDP range isn't open, I cannot open a SSH connection to my
    > linux box.


    Does ssh -vv to the box say anything useful when attempting to auth
    without the port range open?

    > Does anyone know what is going on here?


    Slap wireshark on your box and capture traffice while you're trying to
    connect... and it too can give you clues as to what if anything is
    going on in that port range.

    --
    Todd H.
    http://www.toddh.net/

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