Questions about network ports

Discussion in 'Tech Talk' started by Furant, May 3, 2007.

  1. Furant

    Furant Millennium Member

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    Are all network ports created equal?

    I'm trying to setup a secure shell to a friend's computer, but it appears that her ISP may be blocking ports 22 and 443. I'm considering using something like Port Detective or the Shields Up! web-based tool to confirm this. If it turns out that all ports except the standard email, web, news ports are closed, I assume there's not much I can do. However, would it be possible to use the NNTP (119) port as a TCP connection for SSH if they don't use a usenet client? If not, are there any other ports that I should try configuring the SSH server and client to use?

    She's not behind a router on her system, but it appears that the ISP still assigns her computer a 192.168.1.2 local IP address as if it were behind a router. I'm trying to setup a DNS client so that I can always resolve her dynamic externally-facing IP address.

    Joey
     
  2. Deanster

    Deanster Cheese? CLM Millennium Member

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    It's increasingly common practice to set up SSH on a port other than 22 - it can still be found by doing a port scan, but it will avoid a WHOLE lot of folks who just knock on 22.

    I'd avoid like heck using a port that has a common assigned use - even if it's one you're not using at the moment, it's likely to cause a problem somewhere down the line. Look into one of the 2000 or 3000 series ports...

    As you note, it all depends on how the ISP has things configured - if they're blocking most/all incoming traffic, you're going to have a mighty hard time of it, unless you set up a full-on VPN.
     

  3. stratocastor80

    stratocastor80 NM FTW

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    I don't run many things on standard ports. Got into the habit of starting stuff up on my linux box in the 8000's.. It never gets blocked, have had to switch isps over the years of moving, and not a problem to speak of. I just like it personally (i know whats running on what port)
     
  4. NetNinja

    NetNinja Always Faithful

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    I think you know this but for the sake of other people reading this thread
    192.168 is a class C network address and is non routable or used for small private networks.

    She is behind her router which most ISP's provide a Modem/Router

    She should be able to go into her Modem and allow certain ports.

    Who is her ISP and what make/model is her modem?
     
  5. doktarZues

    doktarZues

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    We had a setup in the Army where SSH came in on 4 different ports which was kind of a added security feature, superuser accounts had to connect on special ports .. I'd be little help directing you how to configure it, but it's very possible, depending on what exact software you're using.

    I'm confident no ISP is blocking 22 or 443 though