Apple - Getting VPN to auto-reconnect on connection drop

You could use the following AppleScript, save it as an application and set it to be a agent (no dock icon).

This script will setup a VPN connection when there is none. Therefore, it should also reconnect shortly after your connection drops. You can change the interval to check your VPN connection, it's 120 seconds in the script.

on idle
    tell application "System Events"
        tell current location of network preferences
            set myConnection to the service "VPN University"
            if myConnection is not null then
                if current configuration of myConnection is not connected then
                    connect myConnection
                end if
            end if
        end tell
        return 120
    end tell
end idle

I've explained how to set this up in this answer.

I made some changes to the provided answer, because if something is worth doing it's worth doing into the ground. I wanted to reconnect if the VPN was dropped, but NOT reconnect if the VPN was intentionally disconnected. The solution I came up with was both effective and inelegant.

First I added hooks to the pppd startup and shutdown to keep track of the desired VPN state. These files should be owned by root, and have world read/execute permissions (sudo chmod 755 /etc/ppp/ip-*).

/etc/ppp/ip-up:

#!/bin/sh
echo true > /var/run/reconnect_vpn
chmod 644 /var/run/reconnect_vpn

/etc/ppp/ip-down: for OS X 10.9.5 and below

#!/bin/sh
tail /var/log/ppp.log | grep '\[DISCONNECT\]'
if [ $? == 0 ] ; then
echo false > /var/run/reconnect_vpn
fi

/etc/ppp/ip-down: for OS X 10.10 and above

#!/bin/sh
tail /var/log/ppp.log | grep '\[TERMINATE\]'
if [ $? == 0 ] ; then
echo false > /var/run/reconnect_vpn
fi

Then by modifying the AppleScript above, I was able to check the '/var/run/reconnect_vpn' status variable to determine whether to bring the VPN back up:

on idle
    tell application "System Events"
        tell current location of network preferences
            set myConnection to the service "VPN"
            set startOnLogin to true
            local doReconnect
            try
                set doReconnect to (do shell script "cat /var/run/reconnect_vpn")
            on error errMsg
                set doReconnect to startOnLogin
            end try
            if myConnection is not null and doReconnect then
                if current configuration of myConnection is not connected then
                    connect myConnection
                end if
            end if
        end tell
        return 120
    end tell
end idle

As before, change the line set myConnection to the service "VPN" to whatever your VPN is called. Also, on startup the 'reconnect_vpn' file doesn't exist, so I added a boolean (startOnLogin) to serve as the default when the file could not be found. I like to start immediately, but if you don't then change it to false.

I have a feeling that if you're the kind of person is this particular about VPN behavior, then you're also the kind of person who likes fumbling around until you find a solution and therefore this answer has no audience. But just in case, here it is. Hope it helps somebody.

There's an app that does it called VPN Auto-Connect (Mac App Store link). It's $0.99.

Once started, it lives in your menu bar; when you use it to turn VPN "on", it will monitor a VPN connection profile you set up in OS X's Network preference pane and ensure you always remain connected to it. VPN Auto-Connect's menu-bar icon provides a list of all the VPN connections you've defined and lets you choose which one to always connect to.