NetNews Usenet Archive 1992 #27

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Internet Message Format | 1992-11-15 | 45.2 KB

Path: sparky!uunet!mcsun!uknet!gdt!uwe-bristol!csd!p_copela From: p_copela@csd.uwe.ac.uk (Phil (SysAdmin Parallel Research)) Newsgroups: comp.os.linux Subject: The EtherNet FAQ - v0.1 (Alpha Test) Message-ID: <1992Nov16.011245.18336@csd.uwe.ac.uk> Date: 16 Nov 92 01:12:45 GMT Sender: usenet@csd.uwe.ac.uk (uwe nntp usenet poster) Reply-To: p_copela@csd.bristol-poly.ac.uk Organization: The New University in the West of England, Bristol (WEB) Lines: 1190 Nntp-Posting-Host: usenet@csd.uwe.ac.uk (uwe nntp usenet poster) Well if I don't post it now I never will. In future this FAQ will be posted on the net channel roughly every 1-2 weeks ======================= The linux ether-NET FAQ ======================= quick disclaimer: I must appologize for my luck of a spoll checkr i) Introduction ------------ Hello and welcome to the wonderful world of linux network communications. Networking has always been one of the most exciting things that you can coax a computer to take advantage of. It allows you to store/retrieve files from remote machines (some of which are probably located in countries which you'll never get to visit) Networking also allows computers to interactively communicate with other processes or users on these remote machines allowing a new social aspect of computing to be approached (mainly in the form of talk or MUD (multi User Dungeon) sessions. Networking also has many stumbling blocks for the administrator to fall over, most notably the initial setting up of a system network can send the most sane person to eating the proverbial hat through the hell of trying to coax their machines into networking life. This FAQ is designed to help you start into networking in a positive direction by leading you simply to the network configuration that best suits you, whether you are a single machine with no network attachment (silly I know) to the multi billion cred networking enviroment of your country's local stock exchange. Please note that this FAQ does not follow the 'normal' format of other FAQ's as it's designed to teach you networking and it's idiosyncacies ii) What you NEED to get started ---------------------------- To use TCP/IP on local ethernet you will need the following 1) A linux machine with linux kernel 0.98.4 2) A WD8003/WD8013 compatible MEMORY MAPPED ethernet card but WD8013 is probably the best to use due to its electronic reconfiguration rather than jumper settings although you'll probably need DOS to set it up You should note that the kernel will always claim to have found a WD8013. If this bothers you, change the printk in linux/net/tcp/we.c to reflect your hardware. *NOTE* no special hardward is needed to communicate with yourself Currently I know of three cards that will work (please tell me if there are more) support for the ne2000 is being worked on but little has been heard of it's progress These are the WD8013, WD8003, and the SMC Elite 16. 3) If you are only going to use 'loopback' mode, you probably won't need a card either! A special loopback device is used to comunicate with yourself 4) some tcp/ip software eg telnet/ftp/talk/finger/rcp/ rsh/various other stuff like daemons etc... 5) Know the IRQ's of your internal cards. 6) A lot of coffee and one of those stress relieving gadgets you can get in the local market. iii) Where to start -------------- First off you'll need to rebuild the kernel with networking compiled into the linux kernel. You do this by removing the '#'s in linux/net/Makefile on lines 13,14 and 26 if they haven't already been removed. Next you'll need to calibrate your network card. Decide what IRQ setting you'll need for the network card. Anyway for those who are frexible, the standard kernel parameters for this are :- INT = 5 mem = D0000 i/o addr = 280 memory start = D0000 memory end = D2000 (8K block for 8003, make it D4000 16k for the wd8013 ) but these can be changed on lines 12-17 (16,17 being the most important) of the file linux/net/tcp/Space.c *NOTE* if you have problems with the memory start addr, please get in touch with bir7@EDU.Stanford.leland Future versions of the TCP/IP code will be setable at boot time via ioctl's. For those of you who do not have the wd8013 card, please refer to the ethernet board documentation on the jumper settings you may have to change. Right, compile the kernel (You may need to do a 'make clean dep Image') and hopefully on the next reboot with the new kernel it should detect your card telling you of the ethernet number it is, and also that a new family of sockets (AF_INET) are available. If your card is incorrectly inserted (I know you wouldn't) it could cause all kinds of errors to be reported. At this stage you have a kernel which supports tcp/ip via the ethernet board in your machine but knows nothing of networking, that is where the software in the tcpip suites becomes important as it is this software that understands networking protocols. iv) The tcpip-0.8.0/tcpip-0.8.1 suites (the history/differances) ------------------------------------------------------------ History of ethernet on linux (by Ross Biro (member of the League for ------------------------------------------------------------------------ Programming Freedom LPF)) 'cos I am not worthy, I am not worthy, I am... ------------------------------------------------------------------------ In reality, I did almost all the work myself, and all from scratch. The jump from slow ftp to the pace we have now was really just some minor patches. This is how it really happened, including why I chose to switch to Linux in the first place. Before I came to Stanford, I had already decided Unix was the way to go and had a 386/20 running Microport (This was just before Microport went chapter 11.(an American bankrupcy (sp?) law) Unix. At stanford I had the opportunity to connect my machine to the Internet (networks have always interested me.) Unfortuneately I couldn't get any sort of networking code for Microport, so instead I bought Esix. Esix had some networking problems, but it was ok. As of 3.2 rev d it had just learned to talk to computers off campus. I spent a lot of time porting networking code to Esix and ran an anon ftp site for it. Then I heard about Linux 0.10. Since my file system had been damaged beyond the ability of fsck to do a complete repair (There was a file in /lost+found with the name " /etc/something" which I couldn't get rid of. This was a file, not a subidirectory or anything.) I decided to back up everything, low-level format my drive and make a linux partition. After repartitioning my hard drive, I discovered my backup tape was unreadable. At that point I made a decision. Since I was going to have to start over I decided to start over with linux. I installed version 0.12 and decided to try my hand at kernel hacking. I wrote a buggy version of ptrace which Linus fixed and included in the kernel (Actually first he included it, then he fixed it.) By this time I was tired of switching to DOS everytime I wanted to use telnet or ftp, so I grabbed the 386bsd source (or is it bsd386) and copied the wd8003 driver. Since It had to be rewritten to work with Linux and I had no clue what it was doing, I introduced many bugs, but it worked well enough to telnet and ftp out using ka9q, so I uploaded it to tsx and posted something to the net. After a while I decided I wanted real networking code, and after my experience with Esix bsd compatible sockets were the way to go. About this time Zorst was just completing the port of X and needed some sort of socket library. He wrote the Unix domain sockets leaving hooks to included other types of sockets later. Which made it unnecessary for me to worry about the kernel/user interface. After serveral hectic months where I moved in with my SO, lost my internect connection and most of the reason for writting the networking code, I finally had something that would let me connect to and from a pc running Clarkson's telnet. I managed to get minamal versions of ftp and telnet to compile and released the first alpha version of the networking code. (The code was all written from scrach by me with out looking at the bsd code.) The things like assuming all ethernet boards are memory mapped was because mine was and I assumed that was the cheapest/simplest way. The ethernet board is not it's own device because that would have required debugging code that was not completely necessary. The first message I recieved about the code was how it had caused the loss of someones hard drive (I've forgotten who, but It was one of the testers who really deserves mentioning.) After 3 or 4 releases with some patches posted to the net channel in between, I began to get the first glimmering of successes from Dirk Hondel (sp?) who was probably the most important of the testers. He provided alot of debugging output and probably risked his file system more than once. About this time Mitch Dsouza(sp?) began to complain that he couldn't even get the patches to compile. After a lot of working (and atleast another release or 2) it worked (sort of) on his machine and many others. At this point Bob Harris started fixing the wd8003 driver (which had suffered from my port from 386bsd). And Russ Nelson at cymwr software began to tell me how other cards worked, and some of what was wrong with my design. Bob Harris also wrote an icmp echo routine so you could ping your linux machine. At this point 0.8.0 was released and I descovered the need for slow start (remeber, I've never been able to test my code on the internet, I've always had to leave that to others.) Not too long after that 0.8.1 was released and my advisor discovered I hadn't gone away for the summer. (Fortuneatly I had been thinking about math enough that he wasn't too upset with my progress.) 0.8.1 was included in the kernel, but none of the support code (mostly config.c) went with it. The rest is mostly just bug fixes and such released with every new version. (Thank you Ross and a big hand from everybody for his efforts) Now an important hint, the config file from 0.8.0 isn't 'good' so please recompile the source 'config.c' from the 0.8.1 distribution and you should find that the protocol not supported message will evapourate. v) The files that you should have and setup info --------------------------------------------- Ok i'll stop blethering and start talking about hard fact files that you should have and where they are supposed to be. the 0.8.0/0.8.1 suites have reasonable enough documentation to get the various working parts out into somewhere useful on your system, typically /usr/etc/inet and /etc having followed the net install shell script you'll probably find that it asked some questions that you hadn't a clue about,... well ok lets look at it. Enter Ip Address for (your host) (aaa.bbb.ccc.ddd) here you are being asked what network address you would like to be known as. Ip address are unique numbers so as to identify you machine from another on a multiuser network. Normally if you reside in the Internet you will have a network address assigned by the NIC or your local network controller and you really must stick to it there is no room for you to bugger up the network by using someone elses ip address. If you do not have a connection to the Internet, you will have less of a problem although it would still be a good idea to apply for a internet class c/d network number depending on your setup. Ip numbers are typically of the 0-255.0-255.0-255.0-255 range so valid answers are 243.123.4.23 or 192.35.173.3 etc but 324.234.545.2 is completely wrong. Enter Net Address for (your hostname) (aaa.bbb.ccc.0) Here you are being asked for your subnetwork address. This requires a bit of explaination. Subnets are a 'unit' of connectivity which depict how many possible hosts 'live' on the same piece of cable as you do (typically this never exceeds 253 on one piece on cable) a quick way of getting the question right is to type in whatever you have for your ip address but make the last number 0 eg if my ip address was 135.56.33.155, my 'safe' Net address would be 135.56.33.0 0.0.0.0 means the whole world and is probably what slip people shoul use. Enter Router Address for (your hostname) (aaa.bbb.ccc.ddd) Wibble! Ok here what is being asked is if you have a gateway machine through which ip traffic can be passed to the great blue yonder. We are sneekily getting the routeing machine to do some hard work for us. Routers tend to have 2 ethernet boards in them whith differing network numbers for them so that they can 'bridge' between different numbered networks, eg you could not talk directly to a ip address of 192.35.173.12 from an ip address of 192.35.175.15 but a machine in the middle with two ip address 192,35.173.4 and 192.35.175.3 can 'collect' the data from the xxx.xxx.173.xxx network and transfer it to the xxx.xxx.175.xxx network All we have to do here is stick in the ip address of the local router in this case it would be 192.35.173.4 (clear as mud I know but it's as good as it gets) If you don't have a router,... just stick in 0.0.0.0 meaning don't route anything. Enter Domain name for (your host) This isn't too bad, domain names are 'convenient' labels eg uwe.ac.uk is the domain name that appends to all the machines on site so that a sun called csd would be known as csd.uwe.ac.uk This is so that you don't have to know the full ip number of the host, it's more convient to call out a semi inteligable name eg 192.35.175.1 = csd.uwe.ac.uk but the 192.35.175 is aliased to uwe.ac.uk (University in the West of England, academic community, United Kingdom) Again this should be given to you with a registered ip address but for now you could put in 'at.linux.net' it can be changed later. Name Server for Domain (aaa.bbb.ccc.ddd) If your networked to the local Uni/technical collage your in luck and it shoul be able to serve you with a name server service, find out from your local network controller what machine distributes the service. If you are unlucky enough NOT to have a nameserver, just stick in your own IP address, you'll just have to run your own nameserver. Ok time for a quick check of what you *SHOULD* have in /usr/etc/inet config - This sets up the ethernet ip tables inetd - Daemon process that invokes other network daemons inetd.conf - Configuration file for inetd about the other daemons install.net - The semi automatic script I just talked about named-xfer - Used for updating the nameserver records named.reload - used to load in the named named.restart - user to stop and restart the named process rc.net - a network rc file called from /etc/rc.local from /etc/rc! services - a file specifying what 'port' numbers certain services are available on telnetd - daemon for connecting reqesting external sites to your machine for interactive logins named - the nameservice daemon time for some explainations I think,... config is a general do it all fix your ether board to your local setup command. It was configured when you ran the install.net script and if you look at the rc.net file you'll see where it plugged in all the IP stuff that you fed the script with,... a bit technical but otherwise nothing to worry too much about provide that your original information was correct. One thing though, I have found that it is best to edit the rc.net file and 'hard wire' the ip addresses directly in rather than relying on the grep search from /etc/hosts but you may disagree (personal preferance) it's the only time that /etc/hosts is actually used as far as I can tell. *** stop press *** Ross: That's a bug. It should be used if /usr/etc/inet/resolv.conf is missing or there is no named running on the machines refered to by resolv.conf. However, it is low on my list of priorities, and probably will not be fixed (by me) any time soon. 'inetd' is a daemon process that wait's for certain events to happen upon which it will select which process to run eg if no network is happening, only inetd will be running but if a telnet session is requested by a remote machine, inetd will start running telnetd for that incoming call to connect to. Of much more intrest is inetd.conf which has information about what services to run and where to find them example sevice name ip/tcp/udp run as name | | | | | format | wait/nowait | program to run | | | | | | | | | | | | | | | telnet stream tcp nowait root /usr/etc/inet/tenetd telnetd talk dgram udp wait root /usr/etc/inet/talkd talkd echo dgram tcp nowait root internal most utilities will tell you what should be included in here should it require editing for to make them run. Services is a file which informs the tcp/ip code what port number a particular program will run on for example if you telnetted to port 7 on a sun you would be connected to an echo service which would send back a carbon copy of what you typed in but that service has a specially allocated port number referenced in the /etc/services file of both machines There is a complete standardized services file in circulation from Ross Biro and is included here for your sanity Ross: This is the one I made from the relevant rfc. It has some typos and such here, but it is probably ok for most use. tcpmux 1/tcp # TCP Port Service Multiplexer rje 5/tcp # remote job entry echo 7/tcp echo 7/udp discard 9/tcp sink null discard 9/udp sink null systat 11/udp users systat 11/tcp users daytime 13/udp daytime 13/tcp daytime 13/udp netstat 15/udp netstat 15/tcp qotd 17/udp quote quote 17/tcp # quote of the day chargen 19/tcp ttytst source chargen 19/udp ttytst source ftp-data 20/tcp ftp 21/tcp telnet 23/tcp smtp 25/tcp mail #Simple Mail Transfer nsw-fe 27/tcp # NSW User System FE [24, RHT] msg-icp 29/tcp # MSG ICP [85, RHT] msg-auth 31/tcp # msg authentication dsp 33/tcp # display support protocol lp 35/tcp # any private printer server [JBP] time 37/udp timserver time 37/tcp timerserver # time rlp 39/udp resource rlp 39/tcp # resource location protocl graphics 41/tcp # Graphics name 42/tcp nameserver name 42/udp nameserver whois 43/udp nicname whois 43/tcp nicname mpm-flags 44/tcp mpm 45/tcp mpm-snd 46/tcp ni-ftp 47/tcp log 49/tcp #login host protocol la-maint 51/tcp # imp local address maintenance nameserver 53/tcp domain nameserver 53/udp domain isi-gl 55/tcp # isi graphics language apts 57/tcp # private terminal access apfs 59/tcp # private file services ni-mail 61/tcp # ni mail [5, SK8] via-ftp 63/tcp # VIA Systems - ftp tacacs-ds 65/tcp # tacacs-database service bootps 67/udp bootp bootps 67/tcp # bootstrap protocol server bootpc 68/udp bootpc 68/tcp # bootstrap client tftp 69/udp tftp 69/tcp # trivial file transfer netrjs-1 71/tcp # remote job service netrjs-2 72/tcp # " " netrjs-3 73/tcp # "" netrjs-4 74/tcp # "" priv-dial 75/tcp # private dial out services rje 77/tcp netrjs # any private rje service finger 79/tcp hosts2-ns 81/tcp hosts2 # hosts2 name server mit-ml-dev 83/tcp # MIT ML Device [DPR] mit-ml-dev 85/tcp # ditto link 87/tcp ttylink # private terminal link su-mit-tg 89/tcp # su/mit telnet gateway mit-dov 91/tcp # mit dover spooler dcp 93/tcp # device control protocl supdup 95/tcp # supdup [27, MRC] swift-rvf 97/tcp # swift remote virtual file protocol tacnews 98/tcp # tac news metagram 99/tcp # metagram relay newacct 100/tcp # unauthorized use hostnames 101/tcp hostname # nic host name server iso-tsap 102/tcp tsap # [16, MTR] x400 103/tcp x400-snd 104/tcp csnet-ns 105/tcp # csnet mailbox name nameserver rtelnet 107/tcp # remote telnet service pop2 109/tcp pop postoffice # post office protocol version 2 pop3 110/tcp # post office protocol version 3 sunrpc 111/udp sunrpc 111/tcp # SUN remote procedure call auth 113/tcp authentication # authentication service sftp 115/tcp # simple file transfer protocol uucp-path 117/tcp # uucp path service nntp 119/tcp # network news transfer protocol erpc 121/udp erpc 121/tcp # encore Epedited remote proc. call ntp 123/udp ntp 123/tcp # network time protocol locus-map 125/tcp # locus pc-interface net map server locus-con 127/tcp # locus PC-interface CONN server pwdgen 129/tcp # password generator protocol cisco-fna 130/tcp # cisco FNATIVE [WX8] cisco-tna 131/tcp # CISCO TNATIVE cisco-sysmaint 132/tcp # CISCO sysmaint statsrv 133/udp statsrv 133/tcp # statistics service ingres-net 134/tcp # ingres-net loc-srv 135/tcp # location services profile 136/udp profile 136/tcp # profile naming service netbios-ns 137/tcp # netbios name service [JBP] netbios-dgm 138/tcp # netbios datagram service netbios-ssn 139/tcp # netbios session service emfis-data 140/tcp # emfis Data Service [GB7] emfis-cntl 141/tcp # emfis control service bl-dim 142/tcp # britton-lee idm imap2 143/tcp # interim mail access protocol v2 NeWS 144/tcp news uaac 145/tcp # uaac protocl [DAG4] iso-tp0 146/tcp iso-ip0 is0-ip 147/tcp # [MTR] cronus 148/tcp # [135, JXB] aed-512 149/tcp # aed 512 emulation service sql-net 150/tcp hems 151/tcp bftp 152/tcp # background file transfer program sgmp 153/tcp # sgmp netsc-prod 154/tcp # [SH37] netsc-dev 155/tcp # sqlsrv 156/tcp knet-cmp 157/tcp # knet/vm command message protocol pcmail-srv 158/tcp # pcmail server nss-routing 159/tcp sgmp-traps 160/tcp snmp 161/udp snmp 161/tcp snmp-trap 162/udp snmptrap 162/tcp cmip-manage 163/tcp # cmip/tcp manager cmip-agent 164/tcp xns-courier 165/tcp # Xerox s-net 166/tcp # Sirius Systems namp 167/tcp rsvd 168/tcp send 169/tcp print-srv 170/tcp # network postscript multiplex 171/tcp # network innovations multiplex cl/1 172/tcp xyplex-mux 173/tcp mailq 174/tcp vmnet 175/tcp genrad-mux 176/tcp xdmcp 177/tcp # X dispaly manager control protocol nextstep 178/tcp bgp 179/tcp # Border Gateway Protocol ris 180/tcp # Intergraph unify 181/tcp unisys-cam 182/tcp ocbinder 183/tcp ocserver 184/tcp remote-kis 185/tcp kis 186/tcp # KIS protocol aci 187/tcp mumps 188/tcp qft 189/tcp # queued file transport [WXS] gacp 190/tcp # gateway access control protocol prospero 191/tcp osu-nms 192/tcp # osu network monitoring protocol irq 194/tcp # internat relay chat dn6-nlm-aud 195/tcp # DNSIX Network Level Module Audit dn6-smm-red 196/tcp dls 197/tcp dls-mon 198/tcp at-rtmp 201/udp at-rmtp 201/tcp # AppleTalk Routing Maintenance at-nbp 202/udp at-nbp 202/tcp # AppleTalk Name Binding at-3 203/udp at-3 203/tcp # AppleTalk Unused at-echo 204/udp at-echo 204/tcp # appletalk echo at-5 205/udp at-5 205/tcp # appletalk Unused at-zis 206/udp at-zis 206/tcp # zone info. at-7 207/udp at-7 207/tcp at-8 208/udp at-8 208/tcp sur-meas 243/tcp # survey measurment dsp3270 245/tcp # display systems protocol link 245/tcp # link biff 512/udp # used by mail system to notify users exec 512/tcp who 513/udp # maintains data bases showing who's login 513/tcp syslog 514/udp cmd 514/tcp syslog 514/udp printer 515/tcp # spooler talk 517/udp ntalk 518/udp utime 519/udp unixtime router 520/udp #local routing process (on site); efs 520/tcp # extended file name server timed 525/udp #timeserver tempo 526/tcp # newdate courier 530/tcp rpc conference 531/tcp chat netnews 532/tcp readnews netwall 533/udp #for emergency broadcasts uucp 540/tcp uucpd klogin 543/tcp kshell 544/tcp krcmd new-rwho 550/udp new-who dsf 555/tcp remotefs 556/tcp # rfs server rmonitor 560/udp rmonitord monitor 561/udp chshell 562/tcp chcmd meter 570/tcp demon meter 571/udp udemon pcserver 600/tcp # sun IPC server nqs 607/tcp mdqs 666/tcp elcsd 704/udp errlog # copy/server daemon loadav 750/udp rfile 750/tcp pump 751/tcp qrh 752/tcp rrh 753/tcp tell 754/tcp send nlogin 758/tcp con 759/tcp ns 760/tcp rxe 761/tcp quotad 762/tcp cycleserv 763/tcp omserv 764/tcp webster 765/tcp phonebook 767/tcp phone vid 769/udp vid 769/tcp cadlock 770/udp rtip 771/tcp cycleserv2 772/tcp notify 773/udp submit 773/tcp acmaint_dbd 774/udp rpasswd 774/tcp acmaint_transd 775/udp entomb 775/tcp wpages 776/udp wpages 776/tcp wpgs 780/tcp mdbs_daemon 800/tcp device 801/tcp maitrd 997/tcp puparp 998/udp busboy 998/tcp puprouter 999/udp applix garcon 999/tcp cadlock 1000/udp blackjack 1025/tcp #network blackjack hermes 1248/udp bbn-mmc 1347/tcp #multi-media conferencing bbn-mmx 1348/tcp # "" ingreslock 1524/tcp orasrv 1525/tcp oracle issd 1600/tcp nkd 1650/tcp dc 2001/tcp wizard 2001/udp curry globe 2002/udp emce 2004/udp CCWS mm conf mailbox 2004/tcp berknet 2005/tcp oracle 2005/udp invokator 2006/tcp raid-cc 2006/udp raid dectalk 2007/tcp raid-am 2007/udp conf 2008/tcp terminaldb 2008/udp news 2009/tcp whosockami 2009/udp pipe_server 2010/udp search 2010/tcp raid-cc 2011/tcp raid servserv 2011/udp raid-ac 2012/udp ttyinfo 2012/tcp raid-am 2013/tcp raid-cd 2013/udp raid-sf 2014/udp troff 2014/tcp cypress 2015/tcp raid-cs 2015/udp bootserver 2016/udp bootclient 2017/udp cypress-stat 2017/tcp rellpack 2018/udp terminaldb 2018/tcp about 2019/udp whosockami 2019/tcp xinupageserver 2020/udp servexec 2021/tcp xinuexpansion1 2021/udp down 2022/tcp xinuexpansion2 2022/udp xinuexpansion3 2023/udp xinuexpansion4 2024/udp ellpack 2025/tcp xribs 2025/udp scrabble 2026/udp shadowserver 2027/tcp submitserver 2028/tcp device2 2030/tcp blackboard 2032/tcp glogger 2033/tcp scoremgr 2034/tcp imsldoc 2035/tcp objectmanager 2038/tcp lam 2040/tcp interbase 2041/tcp isis 2042/tcp isis 2042/udp isis-bcast 2043/udp rimsl 2044/tcp rimsl 2044/udp cdfunc 2045/udp sdfunc 2046/udp dls 2047/tcp dls 2047/udp dls-monitor 2048/tcp shilp 2049/tcp shilp 2049/udp NSWS 3049/tcp rfa 4672/tcp # remote file access server commplex-main 5000/tcp commplex-link 5001/tcp rmonitor_secure 5145/udp padl2sim 5236/tcp xdsxdm 6558/udp man 9535/tcp isode-dua 17007/udp vi) Name Service concepts and what /etc/hosts is about -------------------------------------------------- The internet protocol document defines names, addresses and routes as follows: A name indicates what we seek. An address indicates where it is. A route indicates how to get there. Every network interface attached to a tcp/ip network is identified by a unique 32-bit IP address. A name (hostname) can be assigned to any device that has an IP address. Names are assigned to devices because, compared to numeric Internet addresses, names are easier to remember and type correctly. In use, most of the tcp/ip software on linux can interchangeably use name or ip address but whichever is chosen, it is always the IP address that is used to make connections. Translating names into addressses isn't simply a 'local' issue. The command telnet on.a.linux.net is expected to work correctly on every host that is connected to the network. If the machine is connected to the Internet, hosts all over the world should be able to translate the name into a valid IP address, therefore, some facility must exist on the net for to translate te name into the numeric IP address. There are two methods for doing this,... one involves using a local lookup table (/etc/hosts) and the other uses DNS to remotely interigate the network for the IP address. /etc/hosts is a very simple file which contains a numeric IP address followed by a hostname eg # note that the hash is a comment, no text is processed after # it until the next <cr> # 123.45.67.20 csd csdsun csd.uwe.ac.uk csdsun.ac.uk 123.45.67.21 manic manic.uwe.ac.uk # Tom's machine 123.45.67.22 chef chef.uwe.ac.uk # Main waste of money # other nets 192.35.173.1 hal hal-9000 # local hidden host 192.35.173.2 slave slave.uwe.ac.uk # linux engine 485 25 192.35.173.30 zen zen.uwe.ac.uk # Interactive 2.2.1 386 33 192.35.173.35 thing # external nets 162.34.32.22 weird.emer.cty.oz but clearly this has a limitation in that on large networks ALL machines would have to have this information on disk and that could have 1000's of entries Just think what that means if an extra 120 machines were added! 1000's of machines would have to have their /etc/hosts table updated either by hand or automatic shell scripts calling the list from a main machine,... (see where this is leading?) Enter the DNS service... DNS (Domain Name System) scales well. It doesn't rely on a single large table; it is a distributed database system that doesn't bog down as the database grows. DNS currently provides information on approximately 700,000 hosts. DNS also guarentees thst the new host information will be disseminated to the rest of the network as it is needed. vii) DNS nameserver configuration files and how to fix them ------------------------------------------------------ DNS configuration reqires that a numbet of files be editted in the case of Linux these files are minimally (resolv.conf can be optional) /usr/etc/inet/ resolv.conf or named.boot a_hosts_table (normally called named.hosts) named.boot: domain uwe.ac.uk primary uwe.ac.uk /usr/etc/inet/a_hosts_table resolve.conf: domain uwe.ac.uk nameserver 192.35.173.2 a_hosts_table: @ IN SOA slave.uwe.ac.uk. root.slave.uwe.ac.uk. ( 1.1 ;serial 3600 ;refresh every 10 hours 300 ;retry every 6 minutes 36000000;expire after 1000 hours 3600 ; default dtl is 100 hous ) IN NS slave.uwe.ac.uk. slave IN A 192.35.173.2 hal IN A 192.35.173.1 zen IN A 192.35.173.30 . . . mother IN A 192.35.173.69 For most people, a nameserver will be available in which case the only file really needed is resolv.conf which would contain only the domain name of the site and a nameserver ip address to point to all the named functions are thus the responsibility of the nameserver and not your machine (crafty huh?) Now unfortunately there are those of us that were just plain born unlucky and had to RTFM so,... where a nameserver is not available it is possible to run a nameserver service on your local machine. The following is a list of flies that you will eventually need although just named.boot and a_hosts_table will suffice named.boot: Sets general named parameters and points to the sources of the domain database information used by this server. The sources can be local disks or remote servers. named.ca: Points to the root domain servers named.local: Used to locally resolve the loopback address named.hosts: The zone info file that maps host names to IP addresses named.rev: the zone file for the reverse domain that maps IP addresses to host names (you'll prob never touch it so i'm going to skip it's description unless people get upset enough to lynch me) *** STOP PRESS *** I've just found out from Ross by sheer accident that there is a program release in comp.sources.unix (volume25) called hostcvt (mutter mutter) which is supposidly capable of converting /etc/host entried into the nesessary corrisponding named files. I just pulled it down and it looks quite good although 'out of the box' you'll have to #define R_OK 4 in main.c and fix the bindir/mandir in the makefile. I've NOT run it cos I did all my configuration by hand so I'm too stubborn to let a meer machine do the job I did over 2 day's in 5 seconds. (ah that pride of mine). I know that there have been two patchlevels release but I only added patch1 cos it's a hassle for me to get to the internet (me being on x25 prtocol based JANET). As /etc/hosts file's are amazingly easy to generate this is a handy tool to have and I hope to see it included in the next tcp/ip util kit-bag. *** RESUME PRESS *** named.boot ---------- the named.boot file points to sources of DNS information. Some of these sources are local files; others are remote servers. You only need to create the files referanced in the primary and the cache statements. commands | functions ----------------+-------------------------------------------------------------- directory | Defines a directory for all subsequent file referances primary | Declares this server as primary for the specified zone secondary | Declares this server as secondary for the specified zone cache | Points to the cashe file forwarders | Lists servers to which queries are forwarded slave | Forces the server to only use the Forwarders ----------------^-------------------------------------------------------------- example setups named.boot: ; cache only server ; primary 0.0.127.IN-ADDR.ARPA /usr/etc/inet/named.local cache . /usr/etc/inet/named.ca The loopback domain is an in-addr.arpa domain that maps the address 127.0.0.1 to the name localhost. The idea of resolving your own loopback address makes sense to most people, so most named.boot files contain this entry. named.boot: ; Primary name server boot ; directory /usr/etc/inet primary big.cty.com named.hosts primary 54.152.IN-ADDR.ARPA named.rev primary 0.0.127.IN-ADDR-ARPA named.local cache . named.ca the directory statement tells named that all subsequent filenames are relative to the /usr/etc/inet directory. The first primary statement declares that this is the primary server for the big.cty.com domain and that the data for that domain is loaded from the file named.hosts. The second primary statement points to the file that maps IP addresses from 152.54.xxx.xxx to hostnames. This statement says that the local server is the primary server for the reverse domain 54.152.in-addr.arpa and that the data for the domain can be loaded from the file named.rev Standard Resource Records ------------------------- Resource Record Record type function ----------------------------------------------------------------------------- Start of authority SOA Mark the beginning of a zone's data, and define parameters that affect the entire zone Name server NS Identifies a domain's name server Address A Converts a host name to an address Pointer PT Converts an address to a hostname Mail Exchange MX Identifies where to deliver mail for a given domain name Canonical name CNAME Defines an alias host name Host information HINFO describes a hosts hardware and OS Well Known Service WKS Advertises network services ------------------------------------------------------------------------------ These resourse records are defined in RFC 1033. The format of DNS resourse records is: [name] [ttl] IN type data name: This is the name of the domain object the resource record references. It can be an individual host or an entire domain ttl: time-to-live defines the length of time in seconds that the information in this resource record should be kept in the cache. Usually this field is left blank and the default ttl set in the SOA is used. IN: Identifies the record as an internet DNS resource record. There are other classes of records, but they are not used by the DNS type: Identifies what kind of resourse record this is data: the information specific to this type of resourse record The cache Initialization file ----------------------------- The basic named.ca file contains NS records that name the root servers and 'A' records tha provide the addresses of the root servers. A basic named.ca is shown here named.ca: ; named.ca - typical setup ; ; Servers for the root domain ; 99999999 IN NS tsx-11.mit.edu. 99999999 IN NS nic.funet.fi. ; ; Root servers by addresses ; tsx-11.mit.edu. 99999999 IN A 231.232.21.12 nic.funet.fi. 99999999 IN A 123.45.67.32 note that the ttl is 99999999 the largest possible size so that the root servers are never removed from the cache The named.local file -------------------- The named.local file is used to convert the address 127.0.0.1 (the loopback address) into the name localhost. It's the zone file for the reverse domain 0.0.127.in-addr.arpa. because ALL systems use 127.0.0.1 as the loopback address, this file is virtually identical on every server. named.local: @ IN SOA slave.uwe.ac.uk. root.slave.uwe.ac.uk. ( 1 ; serial 36000 ; refresh every 10 hrs 3600 ; retry after 1 hr 3600000 ; expire after 1000 hrs 36000 ; default ttl is 10 hrs ) IN NS slave.uwe.ac.uk. 1 IN PTR localhost. The named.hosts file -------------------- The named.hosts file contains most of the domain information. This file converts host names to IP addresses, so 'A' records predominate, but it also contains 'MX', CNAME and other records. ; named.hosts file example ; @ IN SOA slave.uwe.ac.uk. probs.slave.uwe.ac.uk. ( 1 ; serial 36000 ; refresh every X seconds 3600 ; retry every X seconds 3600000 ; expire after X seconds 36000 ; default time to live X seconds ) ; define nameservers and mailservers IN NS slave.uwe.ac.uk. IN MX csd.uwe.ac.uk. ; ; define localhost ; localhost IN A 127.0.0.1 ; ;hosts in this zone ; loghost IN A 192.35.173.1 hal IN A 192.35.173.1 zen IN A 192.35.173.30 thing IN A 192.35.173.35 slave IN A 192.35.173.2 IN MX 2 192.35.173.2 servent IN CNAME slave.uwe.ac.uk. mother IN A 192.35.173.69 ; ; outside domains now follow ; csd IN A 192.35.175.1 IN MX 5 192.35.175.1 csdsun IN CNAME csd.uwe.ac.uk. chef IN A 192.35.176.1 ; ;fictional outside gateway midway IN A 166.23.44.2 ; ; etc until you have built a reasonable host table ; that you feel will be adaquate for your network vii) NFS - the network filing system ------------------------------- Network filing systems are convenient mechinisms which allow your machine axcess to more disk space that it actually has by 'borrowing' disk space from another networked machine for either sharing of common data or if allowed, the storing of data generated by your machine. NFS is still in alpha testing and has the unfortunate handicap of not being able to run binaries over the interface due to mmap support not being available at the moment but shell scripts can be run. NFS has several benifits, 1) it reduces local disk storage requirements because a network can store a single copy of a directory, while the directory continues to be fully axcessible to everyone on the network. 2) NFS simplifies central support tasks, becaue files can be updated centrally, yet be available throughout the network 3) NFS allows users to use familiar UNiX commands to manipulate files with rather than learning new ones. There is no need to use rcp/tftp/ftp to copy files, just 'cp' will do NFS is controlled by several files /etc/exports /usr/etc/inet/rc.net The /etc/exports file --------------------- /etc/exports allows your machine to decide what local filesystems it will allow remote clients to NFS mount and decide what access those clients should have to your filespace. Example (I just love examples): /etc/exports allows your machine to decide what local filesystems it will allow remote clients to NFS mount and decide what access those clients should have to your filespace. Example (I just love examples): / -access=slave:moonbeam /usr -ro /home -root=slave:csdsun,-access=slave,csdsun --------v--------------------------------------------------------------- flag | function --------+--------------------------------------------------------------- ro | read only, if this is not specified, the directory is mounted | as read/write. rw | read and write, used to explicitly show that the FS is read | and write root | normally root cannot use root privillages on an NFS FS as that | id is untrusted, :. you would not be able to make a root owned | shell. Unless the root option is used, a UID of 0 translates | to 65536 access | list of hosts who may mount the specified filesystem --------^--------------------------------------------------------------- The /usr/etc/inet/rc.net file ----------------------------- This rc file is used to start the named services and nfs the suggested setup is as follows: . . . if [ -f /etc/portmap ] then echo "Starting portmapper..." /etc/portmap echo "Starting nfsd..." /etc/nfsd echo "Starting mountd...." /etc/mountd echo mount -vt nfs fish:/pub /pub & mount -vt nfs sparky:/mnt/a /test & fi Here if the portmapper isn't running it is started. Once started, it is now possible to hang the nfsd daemon on it as well as the mountd daemon. The two mount commands are from the modified mount command that come with the NFS package and both are run in the background so that if one of the servers were unreachable the system would continue to try while going on to finish the system setup and allow root/users to login. The '-vt nfs' bit isn't nessessary as the mount program understands the nfs syntax and mounts it as an nfs system but I include it anyway. ============================================================================== Touble shooting --------------- One of the most common complaints requards the config command what isn't often noted is that this has to be recompiled from the 0.8.1 sources (available currently on tsx-11.mit.edu: as /pub/linux/ALPHA/tcpip/tcpip-0.8.1.tar.Z). Another problem that crops up is that some binaries that are distributed requires libc.2.2.2 to be present (mine I've no idea what version/wher it came from but it's 173060 bytes long if it helps!) Other people think that it's their version of libraries that casue the problem but can't find the source code for the various utils to recompile. Well sorry folks you are out of luck, the source code for those utils like ftpd and inetd are jealously held back because they are buggy and full of ugly hacks so rather than have the net flooded with complaints, they have been compiled into binary form and shoved out the door with innocent looks about them. Of note are inetd and named from the BSD sources, someone needs to port them as the current ones are erm.. well not really inetd/named. A new telnetd will probably be available after the kernel pty's are fixed which looks as though it'll break a lot of ioctl code. Several things that can help 1) upgrade your kernel to the latest one that you can grab a copy of (currently at time of writting 0.98.4) 2) join the NET mail channel, you can learn an awful lot from the guys on this channel (like the various new copyrighted techniques for tearing out your hair) 3) try and upgrade your C compiler and libraries to at least version 2.2.2d7 4) binary distributions of various network probrams can be found on sunsite.unc.edu,.. always read the README files they are there for a reason! (personal show/contacts/etc..) 5) Depending on your type of problem, contacting the author of the software or the person who ported the software would be a better choice. 6) Complain bitterly to me if I haven't covered your problem and I'll get it sorted for the next FAQ Cast of this production ----------------------- Ross Biro - Without whom all this wouldn't be possible and who pointed out holes in my documentation. Also contributed the history of tcp/ip on linux after he saw my rather perverted view of it. Mitch DSouza - Constant alpha tester. Also pointed out mistakes and made critical and helpfull suggestions (like getting a spell checker). Also gave me his Tel No. which I used to annoy him with. Rick Sladkey - The current Author of the NFS client server code who with the help of Doug Quale repatched the kernel to support networking filesystems. The pioneers - Mentioned in the history of TCP/IP 0.8.[01] by Ross earlier in this FAQ The supporting - You know who you are (probably, depending on how extras much virtual beer you had last night) for contributing to the network code. Linus Torvolds - The elusive ecentric UNiX kernel coder who probably burns more CPU time on compiling than anyone else Here's to a long and healthy kernel development program and a Nobel equiv award for his efforts. Myself - The only sad person to take on the FAQ because I was getting annoyed at the number of 'petty' tcp/ip code problems being asked on the net. Besides of which I wanted to give something useful towards Linux which I've used since 0.10 (does this make me a vetrian?) Phil (The non spell checking insomniacial/palagerist who never learnt =--= english grammer) p_copela@uk.ac.uwe.csd on JANET in the UK and p_copela@csd.uwe.ac.uk elsewhere -- =============================================================================== (c) 1992 Philip Copeland - alias 'Bryce' (SysAdmin) JANET : p_copela@uk.ac.bristol-poly.csd "... I can resist anything but temptation..." -------------------------------------------------------------------------------