Having problems accessing port 8100 after new server and new ISP

Posted on 2008-11-13
Last Modified: 2012-05-05
I recently added a new Windows Server 2003 to replace an old Windows Server 2000 server.  Both servers were on the network until today.  I just transferred all the fsmo roles to the new server and powered it off.  Also, today we got a new ISP.  I went into the router and changed the IP address, subnet mask, G/W address and DNS addresses provided by the ISP, this was the only that was changed on the router.  Everything seemed to be working fine.  All programs on the server was working and we could get to the internet.  This evening we were accessing a website to post our credit card sales.  We got the initial login and entered the first posting and when we went to submit it, we got a TCP/IP connectivity error.    First I called the company and they are not experiencing any problem.  I switched back to our original ISP and made the IP address changes and got the same error.  I even powered up the old server to no avail.  It appears to be a setting on the new server.  Here is the exact issue.

The computer that the WARP Server is running on must be able to establish a TCP/IP client connection on a local port between 1024-500 and talk to a remote server listening on port 8100.  If you are running the viaWARP software behind a firewall, you must take this into account.  Generally, if your firewall is a "stateful" firewall and you have an "inside host rule" policy running it should operate without issue.  If you have an older firewall, or if you are running the software behind a proxy server, you may need to have the firewall and/or proxy server modified to allow connections to port 8100 on internet hosts and

The computer running the viaWARP software must be able to resolve DNS host names.

The originating IP address must be routable across the internet (i.e. cannot be private addresses).  If you are operating behind a proxy server, router or firewall providing NAT services, you must ensure that the source address of the viaWARP server appears to the NOVA servers as routable.

Our server was set up with the basics.  Not a proxy server.  I went into the router (D-Link) and added IP addresses.  The vendor wasn't much help.  They said that we have to allow viaWARP through the firewall to the above 2 websites and ports 8100 and 8101 have to be open.

Any ideas or if you can point me in the right direction would be greatly appreciated.
Question by:FMCBOP
    LVL 5

    Assisted Solution

    Hi Rick,
    The D-Link router probably has port forwarding enabled to forward traffic on port 8100 to your old W2K system, this could be causing the connectivity problems.
    If this isn't the case have you tested DNS resolution? When you ping  does it resolve to an IP address?
    we can start with this anyway.

    Author Comment

    Have not checked port forwarding yet on the router, but will check this afternoon.  As for pinging, it doesn't time out, it comes back as unreachable.  

    LVL 23

    Accepted Solution

    Try seeing if you can connect to 8100 TCP  yourself  via telnet

    telnet 8100

    telnet 8100

    See if the connection successfully establishes.

    Try it from the new server.
    Try it from the old server.
    Try it from a PC.

    Is  windows firewall turned on  @ the new server?

    LVL 5

    Expert Comment

    Unreachable is Ok as long as it resolves to an IP address. I get an unreachable message from a router when I ping as well. I forgot to ask are you able to open web pages etc from the new server? Is the problem strictly limited to this specific connection?
    Could you also try something like :
    open a command prompt Start > Run > cmd
    Type: telnet 25 and press enter
    This should connect you to an email server and will prove that you are able to make a connection on port 25
    Type quit to close the connection.
    If this doesnt work we will know that we need to fix a broader internet problem.


    Author Comment

    Thanks for the responses.  Both experts led me in the right direction to solve the problem.  When we setup for the new ISP, I changed the IP address and the DNS addresses on the D-Link router.  This basically allowed all of our workstations to access the internet.  The problem we had was with this one particular website.  The user was able to access the viaWARP website to login but when they had to post the credit cards, they got the communication error.  I noticed that when the user access the site it had our server IP address in the URL.  When I brought the old server back on the network, everything worked fine.  The problem had to be on the new server, not the router.  I started looking everywhere on the server found a service running called viaWARP.  Both the new server and the old server had the service running.  So, I started looking at the IP settings on the new server.  The new server still had a DNS address of the old server.  So basically, the viaWARP was looking at the old server to solve the naming.  Once I took out that DNS entry and put in the new server IP address, everything worked.  The company was in a little bit of a panic, but problem solved.  This was the first time I ever saw an application work that.  It PC connected to a service on the server then used the servers internet connection to go out to a website.

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