SLIP (Serial Line IP), and PPP (Point-to-Point Protocol) are a widely used protocol for sending IP packets over a serial link. A number of institutions offer dialup SLIP and PPP access to machines that are on the Internet, thus providing IP connectivity to private persons (something that's otherwise hardly affordable).
To run SLIP or PPP, no hardware modifications are necessary; you can use any serial port. Since serial port configuration is not specific to TCP/IP networking, a separate chapter has been devoted to this. Please refer to chapter for more information.