TCP/IP Problems

By bladejtr ยท 9 replies
May 4, 2008
  1. I am attempting to connect to a java based file sharing program. Every time I try to log on it recieves a small packet of information then wont upload and the connection doesnt work.

    I can connect to websites fine and have no problem with torrents or things like that. According to their support I either have a firewall running or a NAT and have to set allowances for firewall or forward a port to allow server to connect. The problem is my cable modem has no routing abilities or firewall and I have a public ip address and I disabled all software firewalls to try to get it to work and still nothing.

    I figured I had some sort of TCP/IP problem so I opened up command prompt and ran ipconfig. Theres no problems with my ip, I can ping, remote sites and ips without a problem including the server for the file sharing program. I have run anti-spyware and virus and nothing is messing me up. I ran winsock fix xp to see if that would help and nothing. I enabled all adapters on TCP/IP filtering and turned off IPSEC. I have no idea what else could possibly be stopping a connection to server.
  2. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Verify you have the latest Jave installed, here->

    Download and run CCleaner, to clean out all temporary files.

    Run all the following commands in Start-->Run-->CMD window:
    • ipconfig /release
    • ipconfig /flushdns
    • ipconfig /registerdns
    • ipconfig /renew
    • net stop "DNS Client"
    • net start "DNS Client"

    Try the "java based file sharing program" again.
  3. jobeard

    jobeard TS Ambassador Posts: 11,173   +989

    your modem has NAT; that's how you got a 172.x.x.x lan address.

    you need documentation from your Java program as to which ports it is trying to use.
  4. bladejtr

    bladejtr TS Rookie Topic Starter

    My modem doest have NAT capabilities its a Motorola Surfboard SB5101. I heard that its possible the ISP is routing for me non-locally and I have to get them to allow a certain port. Is that possible?
  5. jobeard

    jobeard TS Ambassador Posts: 11,173   +989

    hum; the normal flow is to allow all outbound requests and to control/block all inbound data that was not solicited.

    your Java program upload starts the request (ie outbound), and normally the upload
    would flow on the same connection. However, the server on the other end
    (ie the target) can (and apparently is) trying to use a second port for the data transfer (this is exactly like the FTP protocol).

    There are two choices:
    1. check the Java application configuration to make it use one port
    2. get the documentation for the 2nd port number and set port forwarding
      from the router for that port to the lan address of your system
  6. bladejtr

    bladejtr TS Rookie Topic Starter

    Okay but theres no router in my network and that kind of modem has no routing function which means no firewall and it automatically allows all traffic. I was told it was possible that your ISP can be running a router remotely and it has a firewall you cant control from your computer. Is it possible that they can do that or would be?
  7. jobeard

    jobeard TS Ambassador Posts: 11,173   +989

    does NOT have NAT nor SPI and supporting up to 63 additional devices requires
    extra hardware (ie a router with NAT). see spec sheet

    that said, your modem will pass thru everything it sees.

    >the ISP is routing for me non-locally
    hum; familiar with that nominclature

    if ipconfig /all reports your ip address as 172.x.x.x, then the ISP has you
    on THEIR lan router and you do not have a public ip address and YES
    you need them to open ports for you :(
  8. bladejtr

    bladejtr TS Rookie Topic Starter

    I called up Roadrunners tech support. The person I spoke to didn't know what routing, java, or a port was. Ah well.
  9. Blind Dragon

    Blind Dragon TS Evangelist Posts: 3,908

    You should ask to talk to their manager
  10. bladejtr

    bladejtr TS Rookie Topic Starter

    Well the server uses a dynamic port so each user can choose to use whatever they want. So Im asking to have my port changed to the same port World of Warcraft. Im guessing that they had enough people complain about that and its an allowed port. If that doesnt work Im gonna call tech again.
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