iPhone: The Missing Manual, 3rd Edition

Virtual Private Networking (VPN)

The typical corporate network is guarded by a team of steely-eyed administrators for whom Job Number One is preventing access by unauthorized visitors. They perform this job primarily with the aid of a super-secure firewall that seals off the company's network from the Internet.

So how can you tap into the network from the road? Only one solution is both secure and cheap: the Virtual Private Network, or VPN. Running a VPN lets you create a super-secure "tunnel" from your iPhone, across the Internet, and straight into your corporate network. All data passing through this tunnel is heavily encrypted. To the Internet eavesdropper, it looks like so much undecipherable gobbledygook.

VPN is, however, a corporate tool, run by corporate nerds. Your company's tech staff can tell you whether or not there's a VPN server set up for you to use.

If they do have one, then you'll need to know the type of server it is. The iPhone can connect to VPN servers that speak PPTP (Point-to-Point Tunneling Protocol) and L2TP/IPSec (Layer 2 Tunneling Protocol over the IP Security Protocol), both relatives of the PPP language spoken by modems. Most corporate VPN servers work with at least one of these protocols.

The iPhone can also connect to Cisco servers, which are among the most popular systems in corporate America.

To set up your VPN connection, visit Settings→General→Network→VPN. Tap the On/Off switch to make the VPN configuration screen pop up. Tap L2TP, PPTP, or IPSec (that's ...