[Opensim-users] NAT & Corporate Firewall

Fri Apr 1 15:10:47 UTC 2011

InternalAddress is the address internally used by the server to listen for traffic - this parameter is not used to inform the client for use in the handshake.

To set up the UDP handshake the server resolves the ExternalHostName to an IP address.
InternalPort (in your case 9000) is added to the address derived from ExternalHostName.
The server passed that address to the client which then attempts to use it for the handshake.
In your case the server should be sending an IP address like  http://129.137.2.x:9000
However you say you can see at the client that it is using an address like http://10.23.23.x:9000
To me that indicates that on your server ucsim1.irc.uc.edu is resolving to 10.23.23.x which is a problem.

You can see what is used to produce the UDP handshake address using this server command:  
    show region yourregionname

For the parameters that follow the show region command output would include this:

http://something.dyndns-mail.com:9000

Example region parameters which works successfully for internal and external clients:

[REGIONNAME]
RegionUUID = 0d8662a9-e7cb-4552-a701-8bbc3e08ed17
Location = 1001,1000
InternalAddress = 0.0.0.0
InternalPort = 9000
AllowAlternatePorts = False
ExternalHostName = something.dyndns-mail.com
  ----- Original Message ----- 
  From: Fleep Tuque 
  To: opensim-users at lists.berlios.de 
  Sent: Friday, April 01, 2011 09:44
  Subject: Re: [Opensim-users] NAT & Corporate Firewall

  Sorry I haven't replied in a few days, had an inconvenient office move in the middle of all this.  

  Justin wrote:  

  Confusingly, the 'internal port' is used for both the internal UDP listener and is passed to the client as the external connection port.

  It sounds like this might be part of the problem with our campus set up.  I couldn't figure out where the client was even getting the 10.23.23.x internal address to send packets to, but it appears that if I leave the default InternalAddress = 0.0.0.0 in the region.ini file, then somehow that is passed to the off-campus client as the internal IP, which of course doesn't work.

  Will consult with the NOC again with this latest information and many thanks to all for helping shed light on this.

  Sincerely,

  - Chris/Fleep

  Chris M. Collins (SL: Fleep Tuque)
  Project Manager, UC Second Life 
  Second Life Ambassador, Ohio Learning Network 
  UCit Instructional & Research Computing
  University of Cincinnati 
  406E Zimmer Hall
  PO Box 210088
  Cincinnati, OH 45221-0088
  (513)556-3018
  chris.collins at uc.edu

  UC Second Life:   http://homepages.uc.edu/secondlife
  OLN Second Life: http://www.oln.org/emerging_technologies/emtech.php

  On Thu, Mar 31, 2011 at 7:43 PM, Justin Clark-Casey <jjustincc at googlemail.com> wrote:

    From my understanding of the code, using 0.0.0.0 will make the UDP listen to the 'most appropriate' IP address as assigned to the server's NICs (see http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.bind.aspx, IPAddress.Any = 0.0.0.0).

    On a machine with just one NIC this should be fine.  But on a machine with two NICs I'm guessing you would really want to explicitly state the right address.

    The internal address is used to bind the UDP listener.  However, the client is told to connect to the external host name (if this or the port is incorrect then the client connection will timeout on the 'connecting to region' bit).

    Confusingly, the 'internal port' is used for both the internal UDP listener and is passed to the client as the external connection port.

    Some people on Stack Overflow think that IPAddress.Any means listen on all NICs (http://stackoverflow.com/questions/1777629/how-to-listen-on-multiple-ip-addresses).  But my reading of the MS SDK reference above means that it only binds to one.  Anybody able to comment on this?

    And does anybody actually use a non 0.0.0.0 internal address and in what context?  I'd really like to clear up my understanding of this so that we can improve the instructions.

    On 30/03/11 17:28, Adelle Fitzgerald wrote:

      As I understand it, that is used for binding opensim to a specific IP
      address, where the opensim server may have more than one IP address on a
      network interface or multiple network interfaces.

      0.0.0.0 = listen on all available IP addresses, or specify (bind) to a
      specific IP address.

      -----Original Message-----
      From: opensim-users-bounces at lists.berlios.de
      [mailto:opensim-users-bounces at lists.berlios.de] On Behalf Of Edmund
      Edgar
      Sent: 30 March 2011 17:16
      To: opensim-users at lists.berlios.de
      Subject: Re: [Opensim-users] NAT&  Corporate Firewall

      This probably won't help Fleep, but does anyone know what this
      broken-Englished sentence on the wiki is supposed to say?

      # Internal IP address - This should always be 0.0.0.0 (0.0.0.0 means
      "listen for connections on any interface", basically a wildcard) if
      you want to access this server from the internet or another server on
      your internal network, this should be the IP address assigned to the
      OpenSim Server.

      http://opensimulator.org/wiki/Configuration

    -- 

    Justin Clark-Casey (justincc)
    http://justincc.org/blog
    http://twitter.com/justincc

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