Syracuse University Internet Operator's Guide John M. Wobus Communications & Development Computing & Network Services Syracuse University August 31, 1989 Document Number: ISUOPR-1 (c) Syracuse University Computing & Network Services 1989. Copying, in whole or in part, is permitted only for educational purposes and copies must include this copyright notice. Copying or republishing for commercial advantage is prohibited. For per- mission to republish or distribute, write to: Director of Com- puting & Network Services, Syracuse University, Skytop Office Building, Syracuse NY 13244. ABSTRACT This guide is a collection of procedures for coping with Syra- cuse University Internet's operational problems and instructions for using diagnostic tools. Abstract ii CONTENTS Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . ii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 1 Contents of this Guide . . . . . . . . . . . . . . . . . . . 1 What Else Need the Operator Know? . . . . . . . . . . . . . 1 Handling User Problems . . . . . . . . . . . . . . . . . . . . 3 Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 6 A User Cannot Reach Something . . . . . . . . . . . . . . . 6 A User Gets Slow Response . . . . . . . . . . . . . . . . . 7 A User Gets Cut Off when He/She Uses Something . . . . . . . 7 A User Cannot Send Mail to Someone . . . . . . . . . . . . . 8 A Terminal Server Will Not Respond to A Terminal . . . . . . 8 A Workstation Will Not Run . . . . . . . . . . . . . . . . . 8 A Gateway is Down . . . . . . . . . . . . . . . . . . . . . 9 A Network is Down . . . . . . . . . . . . . . . . . . . . . 9 A Server is Down . . . . . . . . . . . . . . . . . . . . . 10 A Node is Unreachable . . . . . . . . . . . . . . . . . . 10 Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 PROBE . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Network Testing . . . . . . . . . . . . . . . . . . . . 14 Displaying Network Status . . . . . . . . . . . . . . . 16 Displaying a Network Map . . . . . . . . . . . . . . . 17 PING . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 TELNET . . . . . . . . . . . . . . . . . . . . . . . . . . 19 FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 HOST . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 NSLOOKUP . . . . . . . . . . . . . . . . . . . . . . . . . 21 GREP and the host table . . . . . . . . . . . . . . . . . 22 XMON and other SNMP Tools . . . . . . . . . . . . . . . . 23 Appendix A: Bibliography . . . . . . . . . . . . . . . . . . 24 Appendix B: Glossary . . . . . . . . . . . . . . . . . . . . 25 Appendix C: Example Internet Operator Job Description . . . 27 Appendix D: Availability of Tools . . . . . . . . . . . . . 28 Syracuse University Internet Operator's Guide iii FIGURES 1. Outline of Internet Symptoms . . . . . . . . . . . . . . . 4 2. Different organizations charged with solving Internet-related problems. . . . . . . . . . . . . . . 5 3. Operator Procedures . . . . . . . . . . . . . . . . . . . 6 4. User on X Cannot Reach Y . . . . . . . . . . . . . . . . . 7 5. User on X gets slow response from Y . . . . . . . . . . . 7 6. User on X using Y gets cut off . . . . . . . . . . . . . . 7 7. User on X cannot send mail to user on Y . . . . . . . . . 8 8. User gets no response from terminal server . . . . . . . . 8 9. User says workstation X won't work . . . . . . . . . . . . 9 10. User reports gateway G is down . . . . . . . . . . . . . . 9 11. User reports Network N is down . . . . . . . . . . . . . 10 12. User reports server down . . . . . . . . . . . . . . . . 10 13. A Checkable Network Configuration . . . . . . . . . . . 10 14. Diagram . . . . . . . . . . . . . . . . . . . . . . . . 11 15. Checking N1 and G1 . . . . . . . . . . . . . . . . . . . 12 16. Checking N2 and G2 . . . . . . . . . . . . . . . . . . . 12 17. Using PROBE to test the network . . . . . . . . . . . . 14 18. Interpreting PROBE output . . . . . . . . . . . . . . . 15 19. PROBE Examples . . . . . . . . . . . . . . . . . . . . . 15 20. Using PROBE to display Network Status . . . . . . . . . 16 21. Example of using PROBE to display Network Status . . . . 17 22. Using PROBE to display a map of the SU Internet . . . . 17 23. Basic form of PING command . . . . . . . . . . . . . . . 18 24. PING's optional parameters on SUVM . . . . . . . . . . . 18 25. PING's optional parameters under Unix . . . . . . . . . 18 26. Usual form of the TELNET command . . . . . . . . . . . . 19 Contents iv 27. Usual format of the FTP command . . . . . . . . . . . . 20 28. Format of the HOST command . . . . . . . . . . . . . . . 20 29. Interpreting the output of the HOST command . . . . . . 21 30. Format of the NSLOOKUP command . . . . . . . . . . . . . 21 31. NSLOOKUP Output . . . . . . . . . . . . . . . . . . . . 22 32. Using GREP and HOSTS to find an Internet Address . . . . 23 33. Examples of using GREP and HOSTS . . . . . . . . . . . . 23 34. Availability of Operator Tools . . . . . . . . . . . . . 28 Syracuse University Internet Operator's Guide v INTRODUCTION The Internet is a world-wide cooperative network made up of many interconnected smaller networks. The Syracuse University Internet is a portion of the Internet that is located at Syra- cuse University. It is made up of several LANs (Local Area Net- works), each of which serves a portion of the University. A sin- gle LAN might serve a building, a hallway, or a single room. All the LANs are connected together by a campus-wide network which is connected, in turn, to a network which serves our region (NYSER- Net, the New York State Educational and Research Network) which is connected via national networks (ARPANET and NSFnet) to other regional networks, and through them to other campuses and their LANs. Not all LANs at Syracuse University are part of the Internet. Networking software comes in different "flavors",(1) an "internet flavor" (also known as TCP/IP) as well as "flavors" specific to various individual computer and network vendors. Internet net- working software has the advantage of tying your computer with virtually all types of computers, and through the Internet, to other Universities and research institutions throughout the world. CONTENTS OF THIS GUIDE This is a guide to operating the Syracuse University Internet. It includes an overview of operational problems, procedures to help the operator address such problems, and descriptions of tools for the operator. WHAT ELSE NEED THE OPERATOR KNOW? The operator of an internet must have some basic knowledge about internets which is not covered by this guide since there are many other manuals that explain it (see bibliography for some examples). Important concepts for the operator include: * Networks * Gateways (a.k.a. Routers) * internets --------------------- (1) Flavor is no standard data-communications term. In standard terminology: There are different, incompatible data- communications protocols that any particular piece of network software may support. Syracuse University Internet Operator's Guide 1 * The Internet * Various LAN technologies (Ethernet, ProNET-10, Appletalk) * Internet names * Internet addresses * Name resolution * Host table * Domain Name Service * Terminal Servers The operator also needs to know what is on the Syracuse Uni- versity Internet, what are its component parts, and what is attached to what. This is covered by the Syracuse University Internet Map and an overview of the Syracuse University Internet, both cited in the bibliography at the end of this document. Introduction 2 HANDLING USER PROBLEMS When a user reports a problem, they are actually reporting a symptom. There are only a few symptoms, but a single symptom may result from any of a number of underlying problems. Furthermore, different problems are the responsibility of different people or groups. Thus, an initial, non-trivial issue is reporting the problem to the right person or group. The following two charts demonstrate the complexity of solving network problems. The first chart lists 5 symptoms along with the different problems that might cause each and whose responsi- bility it is to address the problem. It does not explain how to narrow things down from symptom to problem, but it might be the basis for a useful checklist to help in this endeavor. Syracuse University Internet Operator's Guide 3 +---------------------------------------------------------------+ | 1) User on X cannot reach Y | | - Part of SU Internet is down...............COMDEV | | - Part of Internet away from SU is down.....NOC | | - Part of some Apple Talk LAN is down.......LAN's manager | | - Y is down.................................Y's manager | | - Name "Y" is invalid.......................Consulting | | - Name "Y" is unknown to X..................X's manager | | - X's network software not working..........X's manager | | - User using wrong procedure................Consulting | | | | 2) User on X gets slow response reaching Y | | - Part of SU Internet is busy...............COMDEV | | - Part of Internet away from SU is busy.....NOC | | - X running poor Internet Software..........X's manager | | - Y running poor Internet Software..........Y's manager | | | | 3) User on X using Y gets cut off | | - Part of SU Internet is busy...............COMDEV | | - Part of Internet away from SU is busy.....NOC | | - X running poor Internet Software..........X's manager | | - Y running poor Internet Software..........Y's manager | | - Y went down...............................Y's manager | | - Part of SU Internet went down.............COMDEV | | - Part of Internet away from SU went down...NOC | | | | 4) User on X cannot send mail to user on Y | | - X cannot reach Y..........................See 1) | | - X gets slow response reaching Y...........See 2) | | - X gets cut off sending mail to Y..........See 3) | | - Invalid e-mail address....................Consulting | | - X's mail software not working.............X's manager | | - Some non-internet network is down.........Net's manager | | - User using wrong procedure................Consulting | | | | 5) User gets no response from terminal server X | | - CNS Terminal Server down..................COMDEV | | - Another Dept's Terminal Server is down....X's Manager | | - Terminal down.............................Consulting | | - Part of ACSNET down.......................COMDEV | | - DECCS-LAN down............................NYTEL | | - Phone Company Problems....................NYTEL | | - Problem with wiring.......................CNS Wiring | | | | Figure 1: Outline of Internet Symptoms | +---------------------------------------------------------------+ The condition "part of SU Internet is down" may represent a fail- ure of a gateway, of the wiring, or of some other LAN component. The next chart lists the different organizations responsible for the problems listed in the previous chart along with their responsibilities. Handling User Problems 4 +---------------------------------------------------------------+ | 1) COMDEV | | - Maintaining and operating the CNS-owned portion of the SU | | Internet | | - Maintaining and operating CNS's terminal servers | | - Maintaining and operating ACSNET | | | | 2) CNS Wiring | | - Maintaining wiring between terminal and terminal server | | | | 3) Consulting Services for Users | | - Helping users know the proper procedures | | - Helping users with Internet names of computers | | - Helping users with electronic-mail addresses | | | | 4) Managers of departmental computers | | - Making sure the computer knows names of other computer | | - Internet software on the computer | | - Electronic-mail software on the computer | | - Maintaining and operating their computer | | | | 5) Managers of departmental terminal servers | | - Maintaining and operating their terminal server | | | | 6) Managers of departmental LANs | | - Maintaining and operating the their department's LAN | | | | 7) Managers of non-Internet networks | | - Maintaining and operating their network | | | | 8) Internet's NOCs (Network Operator Centers) | | - Maintaining and operating their part of the Internet | | | | 9) NYTEL | | - Maintaining and operating DECCS-LAN service | | - Maintaining and operating phone service | | | | Figure 2: Different organizations charged with solving | | Internet-related problems. | +---------------------------------------------------------------+ Syracuse University Internet Operator's Guide 5 PROCEDURES To figure out :hp.who:ehp needs to address a particular symp- tom, check for each of the problems that might cause it. The order in which you check depends upon how long and difficult it is to check for each problem as well as how often each problem occurs. Operating experience is the best source of information for these factors. Thus, the procedures listed below are no more than sugges- tions. They will be most useful to the inexperienced network operator, but no doubt can be refined by the operator as he/she gains experience. The following table outlines the procedures described below. +---------------------------------------------------------------+ | Procedures to address User Complaints | | (1) I can't reach something. | | (2) I get slow response. | | (3) I get cut off when I use something. | | (4) I can't send mail to someone. | | (5) The terminal server won't talk to my terminal. | | (6) My workstation won't run. | | (Some knowledgeable users may make the following | | complaints) | | (7) A gateway is down. | | (8) A network is down. | | (9) A (file) server is down. | | | | Procedure to deal with a condition you have established | | (10) You have established that a node is unreachable. | | | | Figure 3: Operator Procedures | +---------------------------------------------------------------+ A USER CANNOT REACH SOMETHING This procedure addresses a user's complaint that they cannot reach some computer. Procedures 6 +---------------------------------------------------------------+ | - See if you can reach Y | | NO: - check the name "Y" | | - Ask Y's manager what is wrong | | - If Y is off-campus, check intervening networks | | - Check SU Internet: use procedure for "A Node is | | unreachable" | | YES: - Ask user to try Y's address instead of Y's name | | - See if you can reach X | | | | Figure 4: User on X Cannot Reach Y | +---------------------------------------------------------------+ A USER GETS SLOW RESPONSE This procedure addresses a user's complaint that they get slow response. +---------------------------------------------------------------+ | - See if you get slow response from Y | | - See if part of net is busy: check intervening gateways | | and networks | | - See if you get slow response from X | | | | Figure 5: User on X gets slow response from Y | +---------------------------------------------------------------+ A USER GETS CUT OFF WHEN HE/SHE USES SOMETHING This procedure addresses a user's complaint that they get cut off while using something. +---------------------------------------------------------------+ | - Ask user if they can get back on | | NO: - Use procedure for when "A User Cannot Reach | | Something" | | YES: - Report to COMDEV engineering | | - See if you can reach Y | | NO: - Use for "A Node is Unreachable" | | YES: - Report to COMDEV engineering | | | | Figure 6: User on X using Y gets cut off | +---------------------------------------------------------------+ Syracuse University Internet Operator's Guide 7 A USER CANNOT SEND MAIL TO SOMEONE This procedure addresses a user's complaint that they cannot send electronic mail to someone. +---------------------------------------------------------------+ | - Is the system manager of X reporting the problem? | | NO: - Report the problem to X's manager | | YES: - Treat as if "A User Cannot Reach Something" | | | | Figure 7: User on X cannot send mail to user on Y | +---------------------------------------------------------------+ A TERMINAL SERVER WILL NOT RESPOND TO A TERMINAL This procedure addresses the complaint of the user of a termi- nal server that they get no response from a terminal server. Some users have terminals directly wired to terminal servers-- such terminals will appear dead if the server is down. There are also terminal servers available through ACSNET to all ACSNET- connected terminals and PCs. +---------------------------------------------------------------+ | - ACSNET's FASTNET command? | | YES: - See if it works for you | | - If not, reload it & test again | | - In any case, report to COMDEV engineering | | - Other ACSNET server? | | YES: - See if it works for you | | - Report to the server's manager | | - Remote terminal server? | | YES: - Report to the server's manager | | | | Figure 8: User gets no response from terminal server | +---------------------------------------------------------------+ A WORKSTATION WILL NOT RUN This procedure addresses a user's complaint that their work- station will not run. Procedures 8 +---------------------------------------------------------------+ | - If it depends on a server, see if server is up | | - Test the network on which workstation X runs | | | | Figure 9: User says workstation X won't work | +---------------------------------------------------------------+ A GATEWAY IS DOWN This procedure addresses a user's complaint that a gateway is down. Some knowledgeable users will know what gateways are and may make this claim. +---------------------------------------------------------------+ | - IP gateway? | | YES: - Can you get through it (use PROBE or PING to | | find out)? | | NO: - Check for possible problem between you | | and the gateway | | - Reload and test | | - Report to COMDEV engineering in any | | case | | YES: get more specific complaint from user | | and/or report to COMDEV engineering | | - Appletalk-to-Ethernet gateway? | | YES: - ?? | | | | Figure 10: User reports gateway G is down | +---------------------------------------------------------------+ A NETWORK IS DOWN This procedure addresses a user's complaint that a network is down. Some knowledgeable users will know about the various net- works and may make this claim. Syracuse University Internet Operator's Guide 9 +---------------------------------------------------------------+ | - Ethernet? | | YES: - Can you reach anything on N (PROBE can check | | everything at once)? | | NO: - Can you reach the gateway to N? | | NO: - Use procedure for "A User Cannot | | Reach Something" | | YES: - ?? | | - Appletalk? | | YES: - Report to COMDEV engineering. | | | | Figure 11: User reports Network N is down | +---------------------------------------------------------------+ A SERVER IS DOWN This procedure addresses a user's complaint that a server is down. Some knowledgeable users will know about the various ser- vers and may make this claim. +---------------------------------------------------------------+ | - Can you reach it? | | NO: - Use procedure for "A Node is Unreachable" | | YES: - Get more specific information from user. | | | | Figure 12: User reports server down | +---------------------------------------------------------------+ A NODE IS UNREACHABLE The following procedure is for discovering which part of the SU Internet is failing.(2) The general strategy is to work back- wards from X to yourself to find the furthest device along the path that works & the first device that fails, e.g. +---------------------------------------------------------------+ | You----Net1--Gateway1--Net2---Gateway2--Net3--X | | | | Figure 13: A Checkable Network Configuration | +---------------------------------------------------------------+ --------------------- (2) This procedure deals only with parts of a network reachable only in one way, i.e. no loops. At the present time, all of the SU Internet is this way. Loops add the complication that when a particular network is down, you might see gateways from a different direction--so additional knowledge and care must be used to locate problems. Procedures 10 First you check Net3, then Gateway2, then Net2, then Gateway1, then Net1 until you find something working. If Net3 and Gateway2 look down and Net2 looks up, that suggests Gateway2 is the prob- lem and you might try reloading it as an emergency measure. +---------------------------------------------------------------+ | N3================ X Y1 Y2 . . . | | | | | | | | N2============= | =======================N1 | | | | | | | +-+--+-----+---+ | | | Gateway G1 | | | +---------+----+ | | | | | M3================== | Z1 Z2 . . . | | | | | | | | M2============== | ============================M1 | | | | | | | +-+---+-----+-+ | | | Gateway G2 | | | +-----+-------+ | | | | | etc. | | | | Figure 14: Diagram | +---------------------------------------------------------------+ To diagnose the network, you must make the following three checks and use your judgement to decide where the problem is most likely to be. You may be able to establish a strong probability that a particular gateway or network is failing. Then a power- off/power-on sequence or a reboot might fix the problem for the short term. Syracuse University Internet Operator's Guide 11 +---------------------------------------------------------------+ | YES NO | | --------- ----------- | | - Can you reach anything on N1? G1 is up & Suggests G1 | | (i.e., Y1, Y2, etc) probably or N1 down. | | working | | correctly. | | Suggests X | | is down. | | | | - Can you reach G1? G1 is up & Suggests G1 | | probably is down. | | working Do the further | | correctly. checking | | listed below. | | | | - Can you reach any other nets G1 is up & Suggests G1 is | | served by G1? probably down. | | (i.e., N2, N3, etc) working | | correctly. | | | | Figure 15: Checking N1 and G1 | +---------------------------------------------------------------+ Further checking to be done if you cannot reach G1: +---------------------------------------------------------------+ | YES NO | | --------- ----------- | | - Can you reach anything on M1? G2 is up & Suggests G2 | | (i.e., Z1, Z2, etc) probably or M1 down. | | working | | correctly. | | Suggests G1 | | is down. | | | | - Can you reach G2? G2 is up & Suggests G2 | | probably is down. | | working Do the further | | correctly. checking | | listed below. | | | | - Can you reach any other nets G2 is up & Suggests G2 is | | served by G2? probably down. | | (i.e., M2, M3, etc) working | | correctly. | | | | Figure 16: Checking N2 and G2 | +---------------------------------------------------------------+ Procedures 12 Further checking follows this same pattern until you reach the computer you are on or until you reach a part of the network rea- chable through more than one gateway. The above procedure assumes the networks N1 & M1 and gateways G1 and G2 are the only way for your computer to reach X. If this is not the case, then the procedure must be modified. Syracuse University Internet Operator's Guide 13 TOOLS PROBE PROBE is something of a catch-all utility, combining several operator functions. Network Testing This is how to use PROBE to figure out why a particular com- puter on the Syracuse University Internet is not available. +---------------------------------------------------------------+ | You must be signed on to SUVM with the COMDEV and CMAINT | | minidisks accessed. PROBE only tests items on the | | Syracuse University Internet. | | | | (1) Type PROBE followed by the name of the item being | | tested and press RETURN. The item may be the | | unqualified name of a computer or gateway or | | may be a computer or gateway's internet address | | or may be the address of a subnet. | | | | (2) PROBE will display a line telling the name and | | date of the file from which it gets information | | about the campus internet. | | | | (3) PROBE does its testing and either gives a message | | telling whether it was successful or not. Then | | it gives an additional message about the further | | tests that it tries. | | | | Figure 17: Using PROBE to test the network | +---------------------------------------------------------------+ The following chart explains PROBE's output. "H" represents the name of the computer which you tested (using the command "PROBE H"). Tools 14 +---------------------------------------------------------------+ | Reached H. | | | | -no problem. | | | | Can't reach H. | | The net to H (net N) works. | | | | -suggests H is down. If not, N is partially up | | and partially down. | | | | Can't reach H. | | Can't verify the net to H (net N). | | | | -suggests network N is down. If not, H is down | | as well as every other node on N. | | | | Can't reach H. | | Can't reach G. | | The net to G (net N) works. | | | | -suggests gateway G is down. If not, network N | | is partially up and partially down. | | | | Can't reach H. | | Can't reach G. | | Can't verify the net to G (net N). | | | | -suggests network N is down. If not, gateway G | | is down as well as every other node on N. | | | | Figure 18: Interpreting PROBE output | +---------------------------------------------------------------+ Following are some examples of using PROBE to test: +---------------------------------------------------------------+ | probe sunrise | | >> 08/02/89 16:00:27 Initializing with IPSUNUMS MEMO F1 | | Probing: SUNRISE | | Reached SUNRISE. | | Ready; T=2.27/2.34 16:00:38 | | | | probe sugrfx | | >> 08/02/89 16:00:45 Initializing with IPSUNUMS MEMO F1 | | Probing: SUGRFX | | Can't reach SUGRFX! | | The net to SUGRFX (net 128.230.24) works. | | Ready; T=2.32/2.42 16:01:07 | | | | Figure 19: PROBE Examples | +---------------------------------------------------------------+ Syracuse University Internet Operator's Guide 15 In the above examples, there are not network problems, SUNRISE is up, and SUGRFX is down. Displaying Network Status The following PROBE functions report network status according to data collected by the FASTMON program. These require access to the COMDEV minidisk but not to the CMAINT minidisk. +---------------------------------------------------------------+ | probe (status -displays the current status of | | the network as seen by | | FASTMON. | | | | probe (today -displays uptime statistics of | | various parts of the network | | for today, from FASTMON. | | | | probe (yesterday -same, but for yesterday. | | | | probe (month -same, but for this month. | | | | probe (report -does all four of the above. | | | | probe (log -displays a log showing when | | when various parts of the | | network went up and down, | | today, collect by FASTMON. | | | | probe (monthlog -same for this month. | | | | probe (X file -where X is one of the above | | options: places the output | | in PROBE OUTPUT A. | | | | Figure 20: Using PROBE to display Network Status | +---------------------------------------------------------------+ Following is an example of one of these commands. Tools 16 +---------------------------------------------------------------+ | probe (status | | Status as of 15:55:39 08/02/89: | | NPAC-MACGATE3 down since 00:16:17 08/02/89 (15 hours). | | SUNGOD down since 12:52:43 08/02/89 (3 hours). | | SUNNSC down since 12:52:43 08/02/89 (3 hours). | | SUGRFX down since 00:04:23 08/01/89 (39 hours). | | Net 128.230.34 down since 12:52:43 08/02/89 (3 hours). | | Net 128.230.22 down since 12:52:43 08/02/89 (3 hours). | | Net 128.230.3 down since 00:04:23 08/01/89 (39 hours). | | Ready; T=0.52/0.57 16:01:15 | | | | Figure 21: Example of using PROBE to display Network Sta- | | tus | +---------------------------------------------------------------+ Displaying a Network Map The following use of PROBE displays an outline-shaped map of the Syracuse University Internet including networks, gateways, and major computers. +---------------------------------------------------------------+ | probe (map root 128.230.12 | | -displays map. | | | | probe (map root 128.230.12 file | | -does the same, but places the | | output in PROBE OUTPUT A. | | | | Figure 22: Using PROBE to display a map of the SU Internet | +---------------------------------------------------------------+ PING PING's basic function is to send a test message to a computer on an internet and wait for the return. Versions of this program reside on SUVM, SUNRISE, RODAN, ICARUS, GAMERA, and many other Unix systems at Syracuse University, but using each is a bit dif- ferent. Most PING programs can be made to send messages repeat- edly and to wait a given time before giving up, but for each PING program, the defaults are different. Syracuse University Internet Operator's Guide 17 +---------------------------------------------------------------+ | ping H | | -where H is a computer's Internet | | name or address. | | | | Figure 23: Basic form of PING command | +---------------------------------------------------------------+ On SUVM by default, PING sends a single message and quits when it receives the answer or times out. You can stop it by aborting the PING program (e.g. by using HX). +---------------------------------------------------------------+ | ping H (count C timeout S | | -where H is a computer's Internet | | name or address, C the number of | | times to try and S is the number | | of seconds to wait each time. | | | | Figure 24: PING's optional parameters on SUVM | +---------------------------------------------------------------+ On many Unix systems, PING repeatedly sends messages by default and reports how long it took each one to return continuously until you stop it with Control-C. +---------------------------------------------------------------+ | ping H Z C | | -where H is a computer's Internet | | name or address, Z is a message- | | length (suggestion: use 0) and C | | is the number of times to send | | messages. | | | | Figure 25: PING's optional parameters under Unix | +---------------------------------------------------------------+ On some Unix systems (SunOS), by default, PING does a single test and says the computer is "alive" or that there was "no answer from" the computer. Tools 18 TELNET TELNET is the Internet user command to sing on to another Internet computer. It is another useful way to check the net- work: if using TELNET to reach a computer gives you a prompt to log in, it has already done considerable communication with that computer: it not only has verified the network, but a considera- ble amount of software in your computer and the computer you are trying to reach. Even if you do not have an account on the com- puter, you can verify that you can receive the login prompt and then abort the connection. Virtually any computer on the Internet has a TELNET command. The usual form is: +---------------------------------------------------------------+ | telnet H | | -where H is a computer's Internet | | name or address. | | | | Figure 26: Usual form of the TELNET command | +---------------------------------------------------------------+ TELNET will usually tell you a way to abort the TELNET connection as you sign on (for example, Control-[ will abort the connection on many computers). Most computers have another way to abort the sign-on procedure, e.g. on Unix, type Control-D at the login prompt, on VAX/VMS (SUNRISE), type Control-Z at the username prompt, and on VM (SUVM), enter the command LOGOFF. FTP FTP is a program to copy files from one computer on an inter- net to another. You can check to see if a computer is reachable with the FTP program. In general, you type FTP followed by the name or address of the computer you are trying to test. If FTP tells you the connection is successful, you can abort it (e.g. use Control-C on a Unix computer or HX on SUVM) before actually signing on and using it. FTP is nearly as useful as TELNET for this purpose. Where TELNET displays actual output from the computer you are trying to reach, TELNET only reports what it has found out, making it a hair less trustworthy. Also, to figure out whether you have suc- cessfully reached the computer, you have to interpret TELNET's messages, which are different for different computers. Syracuse University Internet Operator's Guide 19 +---------------------------------------------------------------+ | ftp H | | -where H is a computer's Internet | | name or address. | | | | Figure 27: Usual format of the FTP command | +---------------------------------------------------------------+ HOST HOST is a program to look up an Internet name using the domain name service and to report its corresponding address. It runs under Unix and is presently available on ICARUS and RODAN. +---------------------------------------------------------------+ | host H | | -where H is the name of a computer | | on the Internet. | | | | Figure 28: Format of the HOST command | +---------------------------------------------------------------+ Following are some of the responses you will get: Tools 20 +---------------------------------------------------------------+ | Host not found. | | | | -The name given was not valid. | | | | H has address A | | | | -The name H is valid. This message is necessary | | if a user is to be able to FTP or TELNET | | the name being tested. | | | | H is a nickname for N | | | | -The name H can be used to do whatever N can do. | | HOST then displays messages about the name N. | | | | H mail is handled by N | | | | -This says nothing about whether the name is OK | | for FTP and TELNET, if the name N is different | | than H, then users can mail to H even if it has | | no address. | | | | Figure 29: Interpreting the output of the HOST command | +---------------------------------------------------------------+ NSLOOKUP NSLOOKUP is similar to HOST but not nearly as convenient. NSLOOKUP is available on GAMERA, ZOOKEEPER, ICARUS, RODAN, and SUNRISE. +---------------------------------------------------------------+ | nslookup H -where H is the name of a computer | | on the Internet. | | | | nslookup H N -this form tells NSLOOKUP what name | | server to use. N is the Internet | | address of a name server. | | | | Figure 30: Format of the NSLOOKUP command | +---------------------------------------------------------------+ Some computers (SUNRISE, GAMERA, ZOOKEEPER, Sun workstations) do not know what nameserver to use unless you specify it to the NSLOOKUP command. The Internet address of a suitable nameserver is 128.230.1.49 (which is ICARUS). NSLOOKUP output is as fol- lows: Syracuse University Internet Operator's Guide 21 +---------------------------------------------------------------+ | Server: N | | Address: A | | | | Name: H | | Address: B | | | | -N and A are the Internet name and address of | | Domain Name Server used to get the answer. | | H and B are the name and address of the | | computer which you asked about. If the | | name you asked about was a nickname, then | | there will be the following line: | | | | Alias: J | | | | -J is the name you asked about. | | | | ** N can't find H: Non-existent domain | | | | -This message replaces the last two when the | | name is invalid. | | | | Figure 31: NSLOOKUP Output | +---------------------------------------------------------------+ Unlike HOST, NSLOOKUP does not automatically look for mail exchangers. GREP AND THE HOST TABLE GREP is a Unix utility for searching files. HOSTS is a file on many Unix systems which holds a table of names and addresses. Using the GREP utility on the HOSTS file gives you information much like that yielded by the commands HOST and NSLOOKUP. How- ever, the HOSTS file does not have every Internet name: only a fraction of them representing "major" computers. Thus, it can tell you that a name is valid, but cannot tell you that a name is invalid: only that it cannot be used by a computer which depends upon this file rather than the Domain Name Service. Systems with GREP and a suitable HOSTS file are RODAN and ICARUS. Tools 22 +---------------------------------------------------------------+ | grep H /etc/hosts | | -where H is the name of a computer | | on the Internet. | | | | Figure 32: Using GREP and HOSTS to find an Internet | | Address | +---------------------------------------------------------------+ Note that the host name must be given in lower-case letters. If the name is not in the host table, there will be no output. Oth- erwise, there will be a single line of output consisting of the address followed by the name (or a list of names). Examples: +---------------------------------------------------------------+ | % grep abc.syr.edu /etc/hosts | | % grep sunrise.acs.syr.edu /etc/hosts | | 128.230.1.1 sunrise.acs.syr.edu sunrise.acs sunrise | | % | | | | Figure 33: Examples of using GREP and HOSTS | +---------------------------------------------------------------+ The first line is asking about a non-existent name: there is no output. The second line asks about the name "sun- rise.acs.syr.edu". XMON AND OTHER SNMP TOOLS SNMP is a package of network management which Syracuse Univer- sity is trying out at the time of the writing of this guide. These tools query the gateways about their own status, then interpret and display the results in various ways. They promise to be very valuable, and will probably be covered by the next edition of this guide. Syracuse University Internet Operator's Guide 23 Appendix A BIBLIOGRAPHY 2. Comer, Douglas. Internetworking with TCP/IP. Englewood Cliffs: Prentice Hall, 1988. 3. Davidson, John. An Introduction to TCP/IP New York: Springer-Verlag, 1988. 4. Hedrick, Charles. Introduction to Administration of an Internet-based Local Network. Center for Computers and Information Services, Rutgers University. 5. Hedrick, Charles. Introduction to Internet Protocols. Cen- ter for Computers and Information Services, Rutgers Univer- sity. 1. Syracuse University Internet Map. Computing & Network Ser- vices, Syracuse University. 6. Wobus, John M. Introduction to Internet Networking. Com- puting & Network Services, Syracuse University. 7. Wobus, John M. Electronic Mail Consultant's Guide. Comput- ing & Network Services, Syracuse University. 8. Wobus, John M. Overview of the Syracuse University Internet Computing & Network Services, Syracuse University. 9. Wobus, John M. Syracuse University Network Bibliography. Computing & Network Services, Syracuse University. [6] gives some background on internets including the "necessary topics" listed in the introduction to this guide. [2], [3] and [5] go into more depth. [1] and [8] are updated periodically and are absolutely necessary for the operator. [9] has references to more documents. Bibliography 24 Appendix B GLOSSARY This glossary is confined to tools described in this document. For a glossary covering more general internet terms, see [6]. FASTMON a program that collects data about the Syracuse Univer- sity Internet. It runs on SUVM as a disconnected vir- tual machine. The data is available through various PROBE options. FTP a user program for transferring files between comput- ers, available on SUVM, SUNRISE, and Unix systems. An FTP program usually gives you a message that with the word "connected" in it after it has traded data with the system. Once you see this message, you have veri- fied the network and the system's connection to the network. It will probably prompt you for a username and password. You can type a dummy username and pass- word, then do a "help" command to find out its command to quit. GREP a Unix utility for searching files. The operator will find it useful to search the list of computer names known to a particular computer for a particular name. HOST a Unix program which is an alternative to NSLOOKUP. It performs the same function, but which, by default, is easier to use and produces output which is easier to interpret. HOSTS a table on most Unix computers which holds a list of internet names along with their associated addresses. NSLOOKUP a program available on many internet computers which looks up the name of a computer in the internet domain name system. It is useful for verifying the name of an internet computer. PING a diagnostic program designed just for this purpose, available on SUVM and on various Unix systems. You type "ping" followed by the system name or number. Different versions produce different output: Unix ver- sions start giving a lot of output when they succeed, but "hang" with a long timeout when they fail. SUVM's PING gives you a message when it succeeds, and times out after a few seconds. SUVM's should be done twice for a reliable answer. PROBE a network diagnostic program available only on SUVM. You type "probe" followed by the system name or number (note: PROBE is peculiar in that it cannot handle Syracuse University Internet Operator's Guide 25 qualifiers--this is in direct opposition to PING, TELNET, and FTP which require qualifiers for most nodes; also, PROBE only functions to reach nodes on the SU Internet). It works something like PING, but when it finds a node down, it automatically checks other nodes to try to identify the reason, e.g., it starts by checking the gateway that reaches the subnet upon which the node resides and if it can reach the gateway, it automatically checks other nodes on the subnet to see if it can reach any of the others. SNMP Simple Network Management Protocol. A protocol by which a computer program can gather network-management data from network nodes. The acronym is also used as the name for some software packages which make use of this protocol to help manage a network. TELNET a user program for signing on to a remote computer, available on SUVM, SUNRISE, and Unix systems. You type "telnet" followed by the name or number of the node. You expect the node to start a sign-on dialog. Once the dialog starts, you have verified that you can reach the node and can go ahead and stop TELNET. Most TELNET programs announce a control character which you can use to tell it you want to give it a command, and usually a HELP command will list what command you can use to abort the session. Another way to abort the session is to use the system you have reached's normal way to abort a sign-on procedure: for Unix, a control-D at the login prompt, for VMS, a control-Z at the login prompt, and for VM, a LOGOFF command. XMON a monitoring program which uses SNMP keep track of the gateways and displays a network map on a workstation screen which shows which part of the network is running and which part is not. It is part of NYSERNet's SNMP software package. Glossary 26 Appendix C EXAMPLE INTERNET OPERATOR JOB DESCRIPTION 1. Act as coordinator for scheduled maintenance on the Syra- cuse University Internet. 2. Answer users' questions concerning Syracuse University Internet and other Internet scheduled downtime and prob- lems. 3. Act as liaison with NYSERNet and NSFnet operations. 4. Collect Syracuse University Internet usage and uptime sta- tistics. 5. Identify possible problems, perform initial checkout to verify their existence, and report problems to engineering. The operator would remain available by telephone and electron- ic mail throughout the working day so that departmental computer administrators and users both from Syracuse University and from other universities have a reliable and timely source of informa- tion. The operator would collect reports of problems and scheduled maintenance that are broadcast throughout the Internet and give informed answers to queries about network availability from Syra- cuse University's network users. Syracuse University Internet Operator's Guide 27 Appendix D AVAILABILITY OF TOOLS The following chart summarizes the availability of operator tools described in this guide on various systems at Syracuse Uni- versity. "Workstation" refers to internal CNS workstations served by GAMERA; workstations served by ZOOKEEPER will have sim- ilar capabilities but not identical. +---------------------------------------------------------------+ | TELNET FTP PING PROBE NSLOOKUP HOST GREP | | SUVM yes yes yes yes* no* no* no | | SUNRISE yes yes yes* no yes* no no* | | RODAN yes yes yes no yes yes yes | | ICARUS yes yes yes no yes yes yes | | GAMERA yes yes yes no yes yes* yes | | ZOOKEEPER yes yes yes no yes* no yes | | Workst. yes yes yes no yes yes* yes* | | | | Figure 34: Availability of Operator Tools | +---------------------------------------------------------------+ Notes marked by asterisk: SUVM/PROBE Requires access to the COMDEV disk. For network test- ing or generating maps, also requires access to the CMAINT disk. SUVM/NSLOOKUP SUVM's NSQUERY is similar. SUVM/HOST SUVM's ADDRESS is similar, but is not generally avail- able at this time. SUNRISE/PING You must type MULTINET PING instead of PING. SUNRISE/NSLOOKUP You must type MULTINET NSLOOKUP instead of NSLOOKUP. SUNRISE/GREP SUNRISE's SEARCH is similar but presently has no equiv- alent to the HOSTS file. GAMERA/HOST At the writing of this manual, HOST is not on GAMERA but there are plans to install it soon. Availability of Tools 28 ZOOKEEPER/NSLOOKUP You must provide the address of the name server. Workstations/HOST At the writing of this manual, HOST is not available to the workstations but there are plans to install it soon. Workstations/GREP The host tables available to the workstations are too small to be useful for this purpose. Syracuse University Internet Operator's Guide 29