Problem accessing application through a gateway

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  • Mauro
    #1

    Problem accessing application through a gateway

    Hi,
    I've a communication problem with my .NET web application and I need
    some suggestions.
    My application is composed of few ASP.NET pages running on a Windows
    2003
    Enterprise Server (.NET 1.1).
    When I access these pages from a browser (Explorer 6.x) in my
    enterprise LAN
    all works right.

    When access these pages from an external PC (this means through a
    gateway and a firewall) in some cases the browser returns something
    like an "Host not found error".

    Note that to avoid problems with "natted" addresses I have set the
    "natted" name of the server in the host file of the client PC.

    The symptoms of the problem are these:
    - when I access the first page all works fine
    - when I access the second page and submit it (using the standard .NET
    postback mechanism) I get an error like "DNS could not locate the
    host".

    Using a sniffer on the server and on the client I can see that:
    - The client correctly sends all the post content on some IP datagrams
    - The server seems not to receive all the data: the information about
    __EVENTTARGET, __EVENTARGUMENT and __STATEVIEW are lost; I don't
    understand if only these pieces of information are lost or if is
    missed the entire IP datagram(s) containing them.
    On the server this sequence of datagrams seems not to be treated as an
    HTTP request (IIS doesn't trace anything about this request) and the
    sniffer on the client traps an HTTP 100 message coming from the server
    (a continue request).

    Note that using a browser on the LAN the server receives all POST data
    (included __EVENTTARGET, __EVENTARGUMENT and __STATEVIEW).

    I don't understand if the problem is the firewall, the gateway, some
    router (fragmentation problem) or something else.

    Any ideas?

    TIA
    Mauro
    Tags: None
    • Konrad Rotuski
      #2
      Problem accessing application through a gateway

      Some firewalls filter not only ports you can connect to,
      but also content of datagrams, maybe in your case firewall
      filtered html content ?

      it seems that it is problems with dns names, maybe try
      telnet thatserver 80
      then :
      GET / HTTP/1.0<enter>
      <enter>

      and see what data is sent to client in both cases

      maybe you should use something like http sniffer to see
      all communication inboth cases

      [color=blue]
      >-----Original Message-----
      >Hi,
      >I've a communication problem with my .NET web application[/color]
      and I need[color=blue]
      >some suggestions.
      >My application is composed of few ASP.NET pages running[/color]
      on a Windows[color=blue]
      >2003
      >Enterprise Server (.NET 1.1).
      >When I access these pages from a browser (Explorer 6.x)[/color]
      in my[color=blue]
      >enterprise LAN
      >all works right.
      >
      >When access these pages from an external PC (this means[/color]
      through a[color=blue]
      >gateway and a firewall) in some cases the browser returns[/color]
      something[color=blue]
      >like an "Host not found error".
      >
      >Note that to avoid problems with "natted" addresses I[/color]
      have set the[color=blue]
      >"natted" name of the server in the host file of the[/color]
      client PC.[color=blue]
      >
      >The symptoms of the problem are these:
      >- when I access the first page all works fine
      >- when I access the second page and submit it (using the[/color]
      standard .NET[color=blue]
      >postback mechanism) I get an error like "DNS could not[/color]
      locate the[color=blue]
      >host".
      >
      >Using a sniffer on the server and on the client I can see[/color]
      that:[color=blue]
      >- The client correctly sends all the post content on some[/color]
      IP datagrams[color=blue]
      >- The server seems not to receive all the data: the[/color]
      information about[color=blue]
      >__EVENTTARGE T, __EVENTARGUMENT and __STATEVIEW are lost;[/color]
      I don't[color=blue]
      >understand if only these pieces of information are lost[/color]
      or if is[color=blue]
      >missed the entire IP datagram(s) containing them.
      >On the server this sequence of datagrams seems not to be[/color]
      treated as an[color=blue]
      >HTTP request (IIS doesn't trace anything about this[/color]
      request) and the[color=blue]
      >sniffer on the client traps an HTTP 100 message coming[/color]
      from the server[color=blue]
      >(a continue request).
      >
      >Note that using a browser on the LAN the server receives[/color]
      all POST data[color=blue]
      >(included __EVENTTARGET, __EVENTARGUMENT and __STATEVIEW).
      >
      >I don't understand if the problem is the firewall, the[/color]
      gateway, some[color=blue]
      >router (fragmentation problem) or something else.
      >
      >Any ideas?
      >
      >TIA
      > Mauro
      >.
      >[/color]

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