Linux PPP HOWTO Prev Chapter 24. Linking two networks using PPP Next 24.3. Network security If you are linking you LAN to the Internet using PPP - or even just to a "foreign" LAN, you need to think about security issues. I strongly urge you to think about setting up a firewall! You should also speak to the LAN administrator at your site BEFORE you start linking to foreign LANs or the Internet this way. Failure to do so could earn you anything from no reaction to really serious trouble! Prev Home Next Setting up the routing Up After the link comes up - the /etc/ppp/ip-up script