NOTE WELL: As announced January 24 2007 by OIT through a variety of media, OIT Remote Access Services this service was discontinued on July 1 2007. A copy of the text of the announcement is available in the OIT KnowledgeBase. As a result, the information in this document is historic.
This document provides some technical information about Princeton's Remote Access Services, for customers with configurations that are not explicitly supported/documented.
If instructions for configuring your particular system for remote access have already been published in another document, then you probably will not need any of the information below. Otherwise, you will probably need some of the information below to figure out how to configure your system to connect with our Remote Access Service.
The 92 modems supporting the regular charged service (phone 806-1000) are currently MICA modems integrated in cisco AS5300 access servers. They support the following standards:
The 14 modems supporting the non-charged service (phone 258-0430) and the 6 modems supported the low-speed charged service (phone 258-0043) are currently US Robotics Total Control modems. They support the following standards:
You should configure as follows:
Below are typical login sequences for the various kinds of service.
In the samples shown below, the text on the left is what the Remote Access Server sends, and on the right is what you would type. 'netid' is your OIT netid, 'secret' is your OIT LDAP Directory password.
Username: netid Password: secret (possibly some announcements and such) comserv> connect hostnamehostname is the name of the host you wish to connect to, e.g. 'arizona'.
Username: netid Password: secret (possibly some announcements and such) comserv> slip default
At this point the Remote Access server will print a message specifying the dynamic IP address assigned to you, as well as the MTU, and it starts SLIP service (IP). You should now start SLIP service on your end.
Username: netid Password: secret (possibly some announcements and such) comserv> ppp default
At this point the Remote Access server will print a message specifying the dynamic IP address that will be assigned to you if you use IP service, as well as the MTU, and it starts PPP service. You should now start PPP service on your end. IP service will start as needed (assuming your client supports IP over PPP).
We also support access to PPP service without responding to comserv's prompts; see Unscripted PPP Service below.
Since you are assigned a dynamic IP addresss, the hostname corresponding to it will vary from call to call. At this time, these names follow the convention comservX-dialupY.princeton.edu, where X and Y are numbers; do not rely on this naming convention as it could change in the future.
OIT does not provide any scripts to automate the login process. If you are writing your own script to automate the login process, be aware that the examples shown above only represent typical login sequences when there are no errors. For an example of a fairly robust script that handled some of the possible errors and timing considerations, you may wish to review this extract from OIT's old MacSLIP Comserv Script. (The script was designed for use on Macintosh computers running MacSLIP (no longer used); it supported both dynamic and Personal IP addresses, over both SLIP and PPP.)
We also support access to our PPP service without proceeding through the comserv login sequences shown above. Since this allows you to connect automatically without manually responding to the prompts or writing a login script, this is known as Unscripted PPP Service.
To use Unscripted PPP Service, configure your PPP client to start PPP after your modem successfully connects to comserv's modem. (I.e. your client should ignore any banner or prompt it may initially receive, nor should your client send any other characters to comserv before starting PPP.) Comserv will detect that your client is speaking PPP (based upon the first character it receives from your client), and will start PPP.
We recommend that you configure your PPP client to pause 3 seconds after successfully connecting to comserv's modem before it starts PPP. This increases the likelihood that comserv will see the first character sent by your client, so it will know to start PPP instead of expecting you to respond to the usual prompts.
You must configure your PPP client to use PAP, the Password Authentication Protocol. Specify your OIT LDAP Directory netid and password. We require the use of PAP to use the Unscripted PPP Service; this provides the authentication function that would would otherwise have been handled by prompts. PPP clients that do not support PAP cannot use the Unscripted PPP Service.
If you need to use a Personal IP Address, then you will not be able to use Unscripted PPP Service; the unscripted service only supports the normal dynamic IP address assignment. If you must use a Personal IP Address, then you will need to connect to comserv via the usual prompt-based login sequence.
Normally a different IP address may be assigned to you each time you dial in. This is called "dynamic IP address assignment."
Some customers have a special need to be assigned the same IP address each time they dial in. We call this a "personal IP address". If you know that you need to use a personal IP address, then you need to request that a personal IP address be assigned to you for remote access use, and login slightly differently.
To request that a personal IP address be assigned to you for remote access use, send email to the Remote Access Account administrator, remote@princeton.edu. In your request, please describe why you need a personal IP address assigned for remote access.
If you registered for something called a "remote access account with IP, PPP, and/or SLIP service" before April 23 1996, then you were assigned a personal IP address. (If you have not used that for at least a year, we may have removed it.)
You can check to see if a personal IP address has been assigned to you for remote access use by checking the Host Database. If your netid is "johndoe", then search for a host named "johndoe.remote.princeton.edu" in the Host Database. If you find an entry, and that entry shows an IP address and has an Entry-Type of REMOTE-ACCESS-PERSONAL-IP-ADDRESS, then you have been assigned a personal IP address. Otherwise, no personal IP address is currently assigned for your remote access use.
When you use a personal IP address, the hostname associated with it is your netid with ".remote.princeton.edu" appended.
Once you are assigned a personal IP address, you must specifically request it each time you login. Change your login sequence as follows:
Username: netid Password: secret (possibly some announcements and such) comserv> slip netid.remote.princeton.edu Password: secret
At this point the Remote Access server will print a message specifying the personal IP address assigned to you, as well as the MTU, and it starts SLIP service (IP). You should now start SLIP service on your end.
If you wish, you can specify netid.remote.princeton.edu the first time you are prompted for a username as well.
Username: netid Password: secret (possibly some announcements and such) comserv> ppp netid.remote.princeton.edu Password: secret
At this point the Remote Access server will print a message specifying the personal IP address assigned to you, as well as the MTU, and it starts PPP service. You should now start PPP service on your end. IP service will start as needed (assuming your client supports IP over PPP).
If you wish, you can specify netid.remote.princeton.edu the first time you are prompted for a username as well.
We do not support the use of a personal IP address with our Unscripted PPP Service.
OIT does provide any scripts to automate the login process. If you are writing your own script to automate the login process, be aware that the examples shown above only represent typical login sequences when there are no errors. For an example of a fairly robust script that handled some of the possible errors and timing considerations, you may wish to review this extract from OIT's old MacSLIP Comserv Script. (The script was designed for use on Macintosh computers running MacSLIP (no longer user); it supported both dynamic and Personal IP addresses, over both SLIP and PPP.)
Our Remote Access Server supports compressed TCP headers for IP (a.k.a. CSLIP, or "Van Jacobsen Header Compression") If you use IP (via SLIP or PPP), we recommend you use this feature; it improves TCP-based throughput.
To ensure compatibility with clients that do not support this feature, comserv will take its lead from the client as to whether it should perform header compression. If comserv sees a compressed TCP header coming from a SLIP client, or if a PPP client negotiates header compression, the Remote Access Server will perform header compression.
Therefore, you should configure your client to always do TCP header compression (a.k.a compressed SLIP, or CSLIP).
If you are using SLIP, we recommend you configure your IP software to use BootP to obtain as much of its IP configuration as possible. (Note that Remote Access Services does not support DHCP.) Details about our BootP service can be found in DHCP and BootP Services. (You may find you still need to manually configure a list of DNS servers; see Domain Name Service.)
If you are using PPP, your software may be able to learn its IP parameters on its own (using IPCP). (Older PPP clients may not be able to learn the list of Domain Name Servers via IPCP; you may need to manually configure them with that information; see Domain Name Service.)
If your software cannot learn its IP parameters via BootP or via PPP's IPCP, you will need to configure them manually. Your IP address (whether dynamic or personal) will be on network (a.k.a. "subnet") 128.112.64.0, which has a subnet mask of 255.255.248.0; the specific IP address for your session is printed by comserv during your login sequence. The default IP router for this subnet is 128.112.64.1, and the broadcast address is 128.112.64.0. If you need to configure your client for Domain Name Service, see Domain Name Service.