SLAC Remote Access Server Security Policies

Approved by ADCC: August 9, 1996

Why do we need to Worry about Remote Access Security?

From time to time, SLAC users have expressed interest in setting up their own SLIP/PPP service or other remote access service (such as the Windows NT Remote Access Server) on one of their machines on the SLAC network in order to provide access to an offsite machine such as a home computer. This would allow a dialin connection directly to a server on the SLAC network, inside the protective Internet firewall screen and not subject to the normal SLAC firewall protections. Such a server could be a potential back door to the entire SLAC network. If not carefully configured, an onsite remote access server would be a serious security risk to all of SLAC's distributed environment.

Currently, SCS does not have the expertise or resources to configure, check, or otherwise manage such remote access servers, and we feel that it is better to put our resources into bringing up the new ISDN service, continuing to support Appletalk Remote Access (ARA), and providing pointers on how to use external SLIP/PPP services, e.g. through campus.

Those who wish to set up remote access servers must obtain prior approval from the Security Committee and meet reasonable guidelines. Such servers must be carefully administered, otherwise crackers may exploit weaknesses to gain unauthorized access to SLAC computers, networks, and/or file systems. In the worst case this could result in the release of sensitive information, modification or destruction of data stored on SLAC's computers, or even damage to apparatus controlled by these computers.

Government laboratories such as SLAC have proven to be tempting targets for crackers. In 1995 an intrusion into SLAC's network from the Internet resulted in SLAC having to sever its connection to the Internet for several days, inconveniencing many remote collaborators who were prevented from performing their normal work at SLAC. In addition considerable time had to be expended checking for and removing effects of the break-in and beefing up security to prevent similar intrusions in the future. Although this attack was probably not performed via a remote access server, it is to everyone's benefit to take reasonable precautions to prevent such intrusions taking place in the future.

The policies described below have been developed to minimize the exposure to remote access server breakins with an acceptable expenditure of effort/resources, while maintaining an environment in which the potential of remote access servers can be effectively exploited by SLAC groups. It must be understood that there is an implicit conflict between the requirements of security, the desire to exploit new technology for SLAC's research and adminstrative needs, and the limited manpower to support new technologies. Even with the implementation of the policies described here, it is not possible to completely assure the security of SLAC's network environment. The level of security described here is thought to be adequate for most of SLAC's current requirements, however it is probably not adequate for applications which deal with highly sensitive information or where human safety may be affected.


In order to provide reasonable security and availability, we recommend that:

If an unauthorized remote access server is discovered, an attempt will be made to contact the owner(s) via phone and Email. If successful the owner will be appraised of the policies on remote access servers and requested to disable the remote access pending authorization. If the attempt to reach the owner(s) is unsuccessful or the user does not disable remote access, then measures will be undertaken to limit the effect (e.g. the server will be barred from the network pending authorization), and the Security Committee will be notified.


Much of the first section was derived from a similar section authored by Tony Johnson in the Web Security Document. We have had useful discussions with Dennis Wisinski on Windows NT Remote Access Services.
Les Cottrell and John Halperin