This document covers setting up OpenBSD to act as a gateway between a small private ethernet network and the Internet using a dial-up connection to an ISP. It assumes that an initial install of OpenBSD has been done and has basic examples of configuring various services.
As the gateway is going to be connected to the Internet, care should be taken with security. Many of the configuration files and programs will need root permission to use. Always be careful to set access to files to the minimum required. Set up sudo, and use it. Don't allow root logins.