Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!ames!sdcsvax!ucbvax!ucdavis!deneb!ccruss From: ccruss@ucdavis.UUCP (Russ Hobby) Newsgroups: comp.protocols.tcp-ip Subject: Re: Where can I find SLIP server for 4.2/3? Message-ID: <737@ucdavis.UUCP> Date: Tue, 1-Sep-87 16:19:32 EDT Article-I.D.: ucdavis.737 Posted: Tue Sep 1 16:19:32 1987 Date-Received: Sat, 5-Sep-87 04:44:09 EDT References: <8708311459.AA25432@oswego> Reply-To: ccruss@deneb.ucdavis.edu (Russ Hobby) Organization: University of California, Davis Lines: 65 Here at UC Davis this summer we have been working on a project to allow PCs to make dialup SLIP connections to the campus IP network. We are also working on abbreviated serial line IP (ASLIP) packeting that will make dialup IP networks more efficient. Here is how the system works. The user logs on to the host that is acting as the gateway, a 4.3 bsd system. He then types in the command "slip" and he becomes a host on the network. He can then use all the programs that come with the CMU/MIT PC/IP or Phil Karn's system. To make connecting to the network a little easier, we have written a program that will do the complete login automatically. The program has a user configurable script file that specifies a sequence of strings to send out the serial line and responses to wait for comming back. It has its own simple language with branching depending on if the correct response came back. The net result is that after the script has been set up, the user types in one command on the PC to connect to the network. Unlike some PC/IPs, our system assumes that each PC (or actually each user) has its own, permanent IP address. Security is provided by logon security on the gateway host. The IP address of the PC is associated with the usercode on the gateway host. The network connection for that PC's IP address can only be started from a user logged in with the correct usercode. The system also makes sure that the IP address is not already connected before making a new connection. The way we have set up IP address for the PCs is to have a separate subnet that contains all the PCs. This way the gateway host needs only to advertise that it is a route to that subnet and all the PCs are covered. In essence the gateway host is the network for all SLIP connections on that subnet. The abbreviated packets work on the assumption that the connecting computer is an end-node and will not be doing any routing. In this case many of the fields in the IP packet are unnecessary. ASLIP uses the minimum header size based on this assumption. With ASLIP the header size is either 8 or 4 bytes, much smaller than the standard 40 bytes. The host that is acting as the ASLIP gateway rebuilds the outgoing packets to legal IP packets before sending them out the network and abbreviates the incoming packets from the network. The login capabilities are currently working. I frequently connect my PC at home via dialup modems( one command "netcon") and use telnet, ftp, whois and smtp. Code for ASLIP is now being written and hopefully will be done by the end of September. At that point we will package up everything necessary to make it work and it will be available to anyone that is interested. Also there have been some terminal server vendors interested in this project. It should not be much work to turn a terminal server into an ASLIP or SLIP server and that would make it cheaper than using a VAX as the gateway. Plus there would not be as much maintainance and downtime with a simple server box. This Fall's project is to take the best of CMU's PC/IP, Phil Karn's IP and Stanford's PC/IP and make a PC package that has the networking interface and services(SMTP,FTP...) running in the background. Client software will run in foreground but will use the background interfaces for connection to the network. Russell Hobby Data Communications Manager U. C. Davis Computing Services BITNET: RDHOBBY@UCDAVIS Davis Ca 95616 UUCP: ...!ucbvax!ucdavis!rdhobby (916) 752-0236 INTERNET: rdhobby@ucdavis.ucdavis.edu