Cisco VPN Client issues

Discussion in 'Mac OS X Server, Xserve, and Networking' started by ericthered, Mar 20, 2009.

  1. ericthered macrumors member

    Jan 31, 2007
    no where
    I have been using a Cisco client to establish VPN connection to my work PC for over a year now and recently something went weird.

    I just replaced my old router with a new Airport extreme and (maybe coincidentally?) then the RDC connection stopped working. It works in XP (running under VMware) just fine.

    Issue seems to be with the system being unable to resolve any DNS requests. Since the issue started, if the VPN client is connected, ALL REQUESTS for DNS resolution time out, including the name address of my work PC. I can connect only by manually entering the IP address of the PC.

    I found this:
    The following problem has occurred with non-Windows VPN Clients. While connected to the VPN Client, DNS resolution to the internal network works at first but fails later in the connection. If the workstation is set to use DHCP and receives a DNS address from the DHCP server, the new DNS overwrites the VPN Concentrator's pushed DNS that had been resolving internal network devices. Once the new DNS has overwritten the Concentrator-pushed DNS, internal devices are no longer resolved properly. Workaround: After connecting to the ISP, record the DNS addresses assigned by the DHCP server and hard code them into the workstation. This prevents the workstation from accepting the DHCP-pushed DNS addresses in the future but still allows resolution when not connected over VPN. The drawback of this is that if the ISP changes their DNS server addresses, the user must find out the hard way and hard code these new addresses once more

    on Cisco's help site but I can't make sense of it - Any help out there??
  2. ericthered thread starter macrumors member

    Jan 31, 2007
    no where
    More info

    I had called Apple about this and they referred me to this:

    but I don't have any clue as to how to enable the NAT-T option in my client, there's no option for that that I can find. Surely someone else has fixed this problem.

  3. ericthered thread starter macrumors member

    Jan 31, 2007
    no where
    fixed it!!

    It turns out that:

    1. the AP Ext DHCP defaults to assigning IPs based using 10.0.x.x addressing
    2. my work network tries to use the same addressing scheme.
    Therefore, I had to change the AP Ext base addressing to 192.168.x.x

    1. Open Airport Utility
    2. Click on the "Internet" tab at the top
    3. Click on the "DHCP" tab within that window
    4. Change the value of "DHCP Beginning Address" from "10.0" to "192.168"
    5. Click Update. You AP Extreme will reboot and once back up, should work fine with your VPN (if you're lucky enough to have similar configuration as mine on your work end of things)

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