------------------------------------------ PROBLEMS CONNECTING TO BCPL FROM ELSEWHERE ------------------------------------------ This is going to be very long, but I urge you to read it because it describes a problem that affects all BCPL account holders. On Saturday morning a water main break in Baltimore near the intersection of Franklin Street and Park Avenue created a huge sinkhole in the street. You probably saw it on TV or read about it in this morning's newspapers. One side effect was that it left the nearby main branch of the Enoch Pratt Free Library without electricity, and broke the datalines serving the Sailor Network Operations Center which is housed at Pratt. Consequently the whole Sailor network is down. BCPL does not depend on the Sailor Network for its Internet connection, but the outage will still affect BCPL Internet users in several ways: o Customers who use Sailor's Baltimore County dialup (410-494-1199) or any other Sailor dialup to get to their UNIX shell accounts will not be able to do so until Sailor is back up. The solution is to use BCPL's own number instead (410-296-5500). o Nothing on the Sailor network is reachable. This includes the Sailor Web site (www.sailor.lib.md.us), and the Web sites and online catalogs of all Maryland libraries who depend on the Sailor network for Internet access. The remaining problems are related to domain name service. I'll explain the DNS tie-in in a moment, but first here are the symptoms: o People at remote sites may not be able to connect to our Web site. o People at remote sites may not be able to send mail to us. Typically their mail will be returned to them with an "Unknown host" error message. o BCPL customers trying to send e-mail to some remote sites may get error messages that say something like this: "<<< 551 ... Domain must resolve". This may happen if the remote site's mail system is configured to reject mail from senders whose domain names cannot be found in the DNS. It's a common anti-spam measure (we use it here). o BCPL customers may not be able to get to their BCPL UNIX shell accounts via telnet, rlogin, or ftp if they are trying to do so from work or from connections to other Internet service providers. o BCPL customers may not be able to collect incoming e-mail from our POP3 mail server if they are trying to do so from work or from connections to other Internet service providers. These problems are symptoms of a breakdown in the Domain Name Service hierarchy caused by the Sailor outage. Here at BCPL we run our own primary name server for the BCPL.LIB.MD.US domain, and there are two secondary name servers for our domain at UUNET. They are working perfectly. It is at the next level above us that the DNS hierarchy is broken, and that level is at Sailor. When a remote site needs to connect to BCPL, it must first learn the numerical IP addresses corresponding to "mail.bcpl.lib.md.us" or "www.bcpl.lib.md.us". To do that it sends out a DNS query, asking "Who knows where I can find BCPL's IP addresses". In most cases the query goes first to one of the "root" name servers, which refers it to a name server for the US domain, which refers it to a nameserver for the MD.US domain, which refers it to a nameserver for the LIB.MD.US domain, which finally refers the remote site to the nameservers for our own BCPL.LIB.MD.US domain. Our nameserver replies "mail.bcpl.lib.md.us = 204.255.212.10", which enables the remote site to make the connection. The problem affecting us now is that both nameservers for the LIB.MD.US domain are at Sailor. Sailor is currently not reachable from the Internet, so neither are the LIB.MD.US domain's nameservers. Because the LIB.MD.US nameservers are unreachable, the DNS hierarchy leading to our own BCPL.LIB.MD.US nameservers is broken. As long as the Sailor network is down, remote sites can't find out how to reach BCPL's nameservers. If they can't reach BCPL's nameservers, they can't learn the IP addresses corresponding to our computer names. Without those IP addresses, they can't connect to our computers. Please note that for the most part this affects only the ability of remote sites to connect to BCPL. Your ability to connect from BCPL to remote sites is affected only if the remote site tries to look us up in the DNS before allowing the connection. Most remote sites don't do that. These problems will persist until the Sailor network is back up. As of the time of this message (5:30 PM Sunday) they are still down, and I have been unable to contact anyone at Sailor to find out how long they expect to remain down. At this stage of the game they probably don't know either. I will post a follow-up via System News as soon as I learn anything new about the situation. In the mean time, here are temporary solutions to some of the problems, and cautions on how NOT to try to deal with some of the others: o If you normally use Sailor's Baltimore County dial-up number (410-494-1199) to connect to your UNIX shell account, use BCPL's own number instead (410-296-5500). o If you need to make a telnet connection to your UNIX shell account from work, school, or another Internet provider, use the IP address of our UNIX host (204.255.212.10) instead of its name (mail.bcpl.lib.md.us). This eliminates the need for a DNS lookup to learn the IP address. o If you need to collect BCPL mail from our POP3 mail server from work, school, or another Internet service provider, use the IP address of our POP3 server (204.255.212.10) instead of its name. This eliminates the need for a DNS lookup to learn the IP address. o If outgoing e-mail is returned to you with a banner like this at the top, DO NOT resend the message: ********************************************** ** THIS IS A WARNING MESSAGE ONLY ** ** YOU DO NOT NEED TO RESEND YOUR MESSAGE ** ********************************************** This means the first delivery attempt failed, but if you read further down in the error report you will see that your message has been put in the mail queue. Our mail system will continue to attempt delivery every hour for the next several days. o If correspondents from other sites complain that they cannot send mail to you, explain the situation and ask that they try again later. DO NOT tell them to send to "jdoe@204.255.212.10". Although that would seem to get around the DNS problem, it doesn't work. Similarly, DO NOT change your e-mail address on outgoing mail to "jdoe@204.255.212.10". Using an IP address as part of an e-mail address is never reliable. o Hang in there! This won't last forever. ------------------------------------------------------------------- If you have questions about this, or about anything else related to your BCPL Internet Account, please contact the BCPL Help Desk. Phone: 410-887-3297 FAX: 410-887-2091 E-Mail: help@mail.bcpl.lib.md.us Help Pages: http://www.bcpl.lib.md.us/help.html (or enter "help" at the UNIX shell prompt) System News Archives: http://www.bcpl.lib.md.us/sysnews.html (or enter "sysnews" at the UNIX shell prompt)