This article is from the the Brief Linux FAQ (BLFAQ) Maintained by Neil Zanella firstname.lastname@example.org
Probably your best bet is to get an Interlink/Laplink/Bi-Directional cable to connect the parallel ports. This method makes use of the PLIP protocol. This will allow your PCs to communicate at a speed of approximately 47kB per second. This is of course somewhat slower than a connection that makes use of Ethernet cards. See the relevant HOWTOs and mini HOWTOs for more detail.