/etc/ppp/ip-up logging script for https://superuser.com/questions/4904/how-to-selectively-route-network-traffic-through-vpn-on-mac-os-x-leopard

0-ReadMe.md

Attempt to manage vpn routing table with /etc/ppp/ip-up

Related Stackoverflow Question:
https://superuser.com/a/206826/55267

Related answer:
https://superuser.com/a/206826/55267

# setup
sudo touch /etc/ppp/ip-up
sudo vim /etc/ppp/ip-up # fill the script
sudo chmod +x /etc/ppp/ip-up
# tail the logs
sudo tail -f /var/log/ip-up.log

Tested on MacOS 10.13 and didn't work for me. Script doesn't get called.
This works, shebang was wrong. Thanks to athairus and Mark Gaensicke in the comments. 🙌

References

• route(8) [osx man page]
• Shebang (Unix) on Wikipedia

Edits

• 2022-11-02: I've updated the script to reflect suggested changes in comments and I've added logging of the command

ip-up.sh

#!/bin/sh
now=`date +%Y-%m-%d_%Hh%Mm%Ss`
logfile=/var/log/ip-up.log

echo "$0 called at $now with following params:" >> $logfile
echo "The VPN interface (e.g. ppp0): $1" >> $logfile
echo "Unknown, was 0, in my case: $2" >> $logfile
echo "IP of the VPN server: $3" >> $logfile
echo "VPN gateway address: $4" >> $logfile
echo "Regular (non-vpn) gateway for your lan connections: $5" >> $logfile

# Add 192.168.0.0 to 192.168.0.255 range to routing table on VPN interface
/sbin/route add -net 192.168.0.0/16 -interface $1 >> $logfile 2>&1

You forgot the bang in the shebang:

#!/bin/sh

See my fork.

With this fix, it works for me on macOS 10.13.16, I needed to update the command to this for my purposes:

/sbin/route add -host 192.168.1.100 -interface $1

First line should be:

#!/bin/sh

instead of #/bin/sh. Without correct Shebang the script will not be executed.

The script still isn't right :)

You wrote:
#/sbin/route add 192.168.0.0/16 -interface $1

The actual call to route should be:
/sbin/route add -net 192.168.0.0/16 -interface $1

Note that:

• Your original made it a comment (by starting with #)
• Without -net it becomes a route for a single address, not for a network.

Thanks I've updated the gist accordingly 👍