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Thread: Destination unreachable (Port unreachable

  1. #1

    Default Destination unreachable (Port unreachable

    I've run into a perplexing network issue that I've not been able to solve.

    I had a network application that worked fine until an update. Then all of a sudden it quit connecting. It works with Mac, and Winblows, but no longer Linux. In this case, I use Playonlinux. The obvious reaction is that it is an application problem. But upon further review it appears to be a port issue. I ran some packet traces and noticed that during the login sequence, I get responses that certain ports of mine are unreachable. I tried turning the firewall off within Yast2, and it made no difference. I then started manually adding port exceptions in the firewall and one by one those went away, but the list was up to about 10 and it was growing. Which lead me to the question why are these ports even close by default? I thought unless blocked should default to open.

    I did an nmap and here is what popped up:

    nmap -p 30000-60000 localhost

    Starting Nmap 6.25 ( http://nmap.org ) at 2014-05-06 21:56 MST
    Nmap scan report for localhost (127.0.0.1)
    Host is up (0.0000070s latency).
    Not shown: 29995 closed ports
    PORT STATE SERVICE
    30000/tcp open unknown
    30001/tcp open pago-services1
    32400/tcp open unknown


    So you can see they are specifically closed! How can I make sure a range of port are open for UDP service? I tried to make a custom rule that says 30000-60000, but that is invalid apparently.

    Any insite into this appreciated.

  2. #2
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    Default Re: Destination unreachable (Port unreachable

    "Port unreachable" is what you see when there is no running process that receives packets on that port. It is not a routing problem.

    So, yes, I would guess that it is a software problem.
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  3. #3

    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by nrickert View Post
    "Port unreachable" is what you see when there is no running process that receives packets on that port. It is not a routing problem.

    So, yes, I would guess that it is a software problem.
    ==============
    Thank you very much for the response. So when nmap shows those ports "closed", it doesn't mean they are shut down, just that nothing is using them then? I am not an expert, so I thought when it said closed, it meant they had to be opened in order to use them. What lead me to believe this line of thinking was right, was when I specifically allowed certain ports to be opened, that the error on that particular port went away, but then another showed up.

    It still seems like what you say is correct, since it DID work fine for months until they did an update. Unfortunately since it is using a wrappers type program they hide behind "we don't support" Linux.

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    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by lshantz View Post
    So when nmap shows those ports "closed", it doesn't mean they are shut down, just that nothing is using them then?
    It probably reports either nothing using the port or blocked, though I'm not an expert on what "nmap" reports.
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  5. #5
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    Default Re: Destination unreachable (Port unreachable

    AFAIK only the firewall would block any port. you tried to shut the firewall down and still couldn't connect. do you know which is the iport where your app Playonlinux tries to connect to? can you reach it using another protocol?

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    Default Re: Destination unreachable (Port unreachable

    A closed port is not a blocked port. It generally means there is no application listening on it.Refer to 'man nmap'

    A closed port is accessible (it receives and responds to Nmap probe packets), but there is no
    application listening on it. They can be helpful in showing that a host is up on an IP address (host
    discovery, or ping scanning), and as part of OS detection. Because closed ports are reachable, it
    may be worth scanning later in case some open up. Administrators may want to consider blocking such
    ports with a firewall. Then they would appear in the filtered state, discussed next.

  7. #7

    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by dmera View Post
    AFAIK only the firewall would block any port. you tried to shut the firewall down and still couldn't connect. do you know which is the iport where your app Playonlinux tries to connect to? can you reach it using another protocol?
    I didn't take it that far. I have come to the conclusion it HAS to be a software issue. I have not changed my system, it worked for months fine, they pushed a new update on me, and it quit working. I was hoping I could work around it, but they have slammed the door in my face with, "we do not support linux". They will not help in any way. I guess I could get some hack tools to portscan myself, but if memory serves, that shows "open" ports for something that it is actively listening to. Not a passively listening port.

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    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by lshantz View Post
    I didn't take it that far. I have come to the conclusion it HAS to be a software issue.
    Almost for sure.

    I have not changed my system, it worked for months fine, they pushed a new update on me, and it quit working. I was hoping I could work around it, but they have slammed the door in my face with, "we do not support linux". They will not help in any way. I guess I could get some hack tools to portscan myself, but if memory serves, that shows "open" ports for something that it is actively listening to. Not a passively listening port.
    Out of interest, what is the software you are referring to?

  9. #9

    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by deano_ferrari View Post
    Almost for sure.


    Out of interest, what is the software you are referring to?
    Don't laugh. World of tanks. One of the side benefits of getting this to work was learning about Playonlinux. What a great little wrapper! Google quit supporting Picasa for Linux awhile back and I found out by accident that I can use Playonlinux to install Picasa through it. Works better than ever!

    So now I'm stuck playing WOT on a mac laptop. Ironically the playonmac wrapper works. ??

  10. #10
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    Default Re: Destination unreachable (Port unreachable

    Quote Originally Posted by lshantz View Post
    Don't laugh. World of tanks. One of the side benefits of getting this to work was learning about Playonlinux. What a great little wrapper! Google quit supporting Picasa for Linux awhile back and I found out by accident that I can use Playonlinux to install Picasa through it. Works better than ever!

    So now I'm stuck playing WOT on a mac laptop. Ironically the playonmac wrapper works. ??
    You might try casting your net wider by posting in the Steam and/or PlayOnLinux forums...

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