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Thread: [SOLVED] ports sometime closed

  1. #1
    Join Date
    Sep 2006
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    Chicago, Illinois
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    Ubuntu 10.04 Lucid Lynx

    [SOLVED] ports sometime closed

    I am having an unusual issue. I hope someone may have some insight for me.
    I have 3 computers. Lets call them home, work and server.

    When connecting through ssh I can connect:
    - from home to server
    - from server to work
    - from home to server to work
    but when I try to connect from home to work I get:
    Code:
    ssh: connect to host ems4.rrc.uic.edu port 22: Connection refused
    Also when I nmap from home to work I get:
    Code:
    Starting Nmap 4.53 ( http://insecure.org ) at 2008-06-24 21:48 CDT
    All 1714 scanned ports on work.workserver.com (***.***.***.***) are closed
    
    Nmap done: 1 IP address (1 host up) scanned in 0.235 seconds
    though from server (or home to server) to work I get:
    Code:
    Starting Nmap 4.53 ( http://insecure.org ) at 2008-06-24 21:51 CDT
    Interesting ports on work.workserver.com (***.***.***.***):
    Not shown: 1707 closed ports
    PORT     STATE SERVICE
    22/tcp   open  ssh
    111/tcp  open  rpcbind
    113/tcp  open  auth
    631/tcp  open  ipp
    1234/tcp open  hotline
    5900/tcp open  vnc
    8000/tcp open  http-alt
    
    Nmap done: 1 IP address (1 host up) scanned in 0.129 seconds
    I wonder if this is due to the ssl key stuff, but then why could I go from home to server but not home to work. And besides nmap comes up empty too which would not have anything to do with ssl. So perhaps I am off base there.
    As a note all comps are running Ubuntu 8.04 and are regularly updated, the server does not run X.
    Thanks for any help
    Last edited by stringkarma; June 25th, 2008 at 03:56 AM.

  2. #2
    Join Date
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    Re: ports sometime closed

    So I have been doing some testing and the nmap results are the most important. I have been trying to vnc in from various computers and they all work (even some windows boxes) except from the "home" computer.

    Basically it comes down to all ports on work are closed to "home," but ports are open to all others.

    Any ideas?

  3. #3
    Join Date
    Feb 2008
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    Re: ports sometime closed

    Quote Originally Posted by stringkarma View Post
    So I have been doing some testing and the nmap results are the most important. I have been trying to vnc in from various computers and they all work (even some windows boxes) except from the "home" computer.

    Basically it comes down to all ports on work are closed to "home," but ports are open to all others.

    Any ideas?
    Can you paste the Netmask of all machines?

  4. #4
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    Re: ports sometime closed

    From ifconfig:
    home has mask: 255.255.255.0
    server: 255.255.255.0
    work: 255.255.255.0

    Is this what you were asking for?
    If not let me know.

  5. #5
    Join Date
    Feb 2008
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    Re: ports sometime closed

    Quote Originally Posted by stringkarma View Post
    From ifconfig:
    home has mask: 255.255.255.0
    server: 255.255.255.0
    work: 255.255.255.0

    Is this what you were asking for?
    If not let me know.
    Ok, the netmask seems ok..
    Just to make sure.. did you update your ssh client and server?
    if not..
    login as root... and do:

    apt-get update
    apt-get dist-upgrade

    when you do this, the dist-upgrade will show you what packages needs to be updated, tell me if openssh is in the list and also, when it is.. just upgrade/update it..

  6. #6
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    Re: ports sometime closed

    As I said, I keep my computers updated, all the same I just did the upgrade and after today's new updates (the closest of which was vino) I never saw any openssh packages.

    To add to the pool of knowledge I installed an ssh client on my wife's computer (Vista) which is also wirelessly connected behind my home router. Her's was able to connect to the work computer. This confirms that it is not the settings of the router.

    As I am able to connect to the server (outside the router) I think I am left to think that either home blocks connections to work or work blocks connections from home. I think perhaps active blocking, perhaps blacklisted somehow.

    Also Thanks Vascotia for the attention.

  7. #7
    Join Date
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    Re: ports sometime closed

    Your home machine might be blocked at your work's end. Some IT departments get nervous about who they let in.
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  8. #8
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    Re: ports sometime closed

    see my other thread on this if you need an answer to a similar problem:

    http://ubuntuforums.org/showthread.php?t=843388

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