1. Introduction

This very brief document describes how to set up a serial “laplink” connection between two Linux machines or a Linux and a Windows machine. The serial link consists of a “null-modem” cable and a communication protocol: PPP. I use such a setup to send files to and from my laptop; it can also quite nicely be used to install new software from a cd-rom when a laptop doesn't have one. I had more trouble than I should have had when setting up my serial laplink. Hopefully this document will solve your problems in one go (the ones to do with the serial cable anyways).

Both server and client side of the setup I will describe could be either a Linux machine or a different operating system, as long as it supports the PPP protocol on a null-modem. The MS Windows implementation, as it turns out, is slightly different from standard, requiring some special attention. This document has two main sections. The first describes how to setup the server side. This is the main station with a serial port dedicated to a PPP connection. Alternatively the connection can be started when needed from the command line. The second part describes the configuration of the client that connects to the server to retrieve or upload files.

This documentation was prepared for pppd version 2.3.11, on a version 2.2.16 kernel.

Please let me know if you are having any particular difficulties and suggestions for improvements on this document; my email address is listed at the bottom.