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Help debugging standard Gateway configuration problem

579 Views 11 Replies Latest reply: Mar 16, 2012 8:05 AM by Brettermeier RSS
Gavin Lawrie Level 2 Level 2 (370 points)
Currently Being Moderated
Mar 14, 2012 3:08 PM

I've got a Mac Pro running Lion Server.


It connects to a fixed IP / direct connection to the Internet on Ethernet 1.


The machine, and the services it supports all have good access to the Internet.


It is configured to support a LAN from Ethernet 2.  Wifi connection is disabled.


I used the Gateway Assistant to set up, and:


  • Ethernet 2 is configured at, with DNS set manually to OpenDNS values.  These are the same values as used on Ethernet 1's fixed IP connection (which works fine).
  • NAT is set to IP Forwarding and Network Address Translation, External Interface is Ethernet 1, and Port Mapping Protocol is enabled.
  • DHCP is set to distribute values to en1 (which is Ethernet 2) in range to  DNS is set to


The problem I have is, is that although client connections to Ethernet 2 set up pefectly, the connected machines have no connection to the internet: unable to see fqdns or ping IPs directly.


I must be doing something wrong... but can't see it.  Hopefully someone else can...


Thanks in advance for whatever help anyone can provide.

Mac Pro, Mac OS X (10.6.8), 9Gbytes - OS X Server
  • Brettermeier Level 1 Level 1 (25 points)



    Is the address at en0 static? To check the settings provided by your dhcp server open up a terminal on your client machine and type ifconfig. Maybe a simple typo at the gateway address is the answer. Try to (tmp) disable the firewall and check if your server resloves dnslookups.


    From time to time i have the same issue that no packets goes through the connection sharing. -> Restart fixed that

  • Brettermeier Level 1 Level 1 (25 points)

    Does your server answers dns querys from the clients?

  • Brettermeier Level 1 Level 1 (25 points)

    Could you please paste the output from an serverside "ifconfig" and a "nslookup yourserverip" from your server and client.

  • ProtocolGeek Level 1 Level 1 (0 points)

    Firebind has a test that can let you know whether the Bonjour TCP and UDP ports listed in the Apple Support FAQ are being blocked or not.

    It will test TCP 5297 and 5298 as well as UDP 5298 and 5353 to confirm there is no firewall blocking them.


    If you have other ports you want to test besides the Bonjour ports then you can enter custom port ranges as well through their Applet client.

    - ProtocolGeek

  • Brettermeier Level 1 Level 1 (25 points)

    I'm a little bit confused about your serverside en0. En0 has 2 ip addresses and Is that a dual port nic with load balancing activated or a VLAN? If its no problem try to disable the second nic port (or VLAN) so that en0 uses only 1 ip.  Make sure that nat uses the right external nic (en0).

  • Brettermeier Level 1 Level 1 (25 points)

    One machine with 2 ip adresses in the same subnet could end up in a routing problem. Im not sure if NAT can handle that. Try to temp disable the mail service, delete VLAN2 on en0 (.46) restart the server and use the gateway assistant again with en0 (45) as your external device.


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