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Article:
  VPN on Mac OS X
Subject:   Re: Loss of internet when connected to VPN
Date:   2003-03-12 15:01:52
From:   jldera
Response to: Loss of internet when connected to VPN

Your default gateway is determined by the order of your network interfaces in the Network pane of System Preferences. Whichever interface is at the top of the list will be the default gateway. If that interface isn't availble, the next in the list will be the default gateway, and so forth. What you want to do is be sure that the interface used for your Internet connection is above the one for PPTP.


To change the order, select "Network Port Configurations" from the Show drop down menu. This will display a screen which allows you to drag and drop your interfaces into the desired order.

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  • Re: Loss of internet when connected to VPN
    2003-03-13 11:49:33  anonymous2 [View]

    Thanks for the reply.
    I have checked the order and Built-in Ethernet is above PPTP.
    netstat -r normally gives:
    Destination Gateway Flags Refs Use Netif Expire
    default 192.168.1.1 UGSc 6 4 en0
    127.0.0.1 127.0.0.1 UH 14 3290 lo0
    169.254 link#4 UCS 0 0 en0
    192.168.1 link#4 UCS 1 0 en0
    192.168.1.1 0:20:78:da:e3:e2 UHLW 6 0 en0 868
    192.168.1.50 127.0.0.1 UHS 0 1 lo0

    After connecting the VPN
    Destination Gateway Flags Refs Use Netif Expire
    default 10.1.2.150 UGSc 1 5 ppp0
    10.1.2.150 10.1.2.151 UH 2 0 ppp0
    127.0.0.1 127.0.0.1 UH 13 4107 lo0
    169.254 link#4 UCS 0 0 en0
    192.168.1 link#4 UCS 1 0 en0
    192.168.1.1 0:20:78:da:e3:e2 UHLW 1 0 en0 1092
    192.168.1.50 127.0.0.1 UHS 0 1 lo0
    vpnsvr_address 192.168.1.1 UGHS 1 1 en0

    Note: vpn server address obscured for security
    It appears the VPN ppp0 interface completely replaces the default routing. Reversing the order makes no difference.

    I can set the routes manually each time, but I don't believe this should happen.
    I would expect to get a route to 10.0.0.0/8 via 10.1.2.150 and the default route left alone.
    Note it adds a route via the original default gateway to the address of the VPN server.
    There appears to be no way of setting no default route for the pptp interface.

    Any other ideas,
    Alban
    • Re: Loss of internet when connected to VPN
      2003-11-17 17:40:27  anonymous2 [View]

      I found an automated script for correcting the route here:
      http://www.macosxhints.com/article.php?story=20030313194656474

      works well for me, in panther, after some small mods.

      -millz
    • Jason Deraleau photo Re: Loss of internet when connected to VPN
      2003-03-13 11:53:10  Jason Deraleau | O'Reilly Author [View]

      Hmm. Coincidentally, this hint came through Mac OS X Hints earlier today:

      http://www.macosxhints.com/article.php?story=20030311232930261&mode=print

      It describes how to run pppd to make the VPN connection by hand, allowing you to remove the defaultroute statement. Apparently this is an unforeseen circumstance on Apple's behalf.