Newsgroups: comp.os.linux.announce,comp.os.linux,news.answers,comp.answers
Path: sparky!uunet!portal!!caen!batcomputer!theory.TC.Cornell.EDU!mdw
From: m...@TC.Cornell.EDU (Matt Welsh)
Subject: [comp.os.linux] Linux Networking FAQ (Part 1)
Message-ID: <>
Followup-To: poster
Originator: m...@theory.TC.Cornell.EDU
Keywords: Linux TCP/IP Networking
Organization: Cornell Theory Center
Date: Thu, 18 Feb 1993 20:28:53 GMT
Approved: (Matt Welsh)
Lines: 765

Archive-name: linux-faq/networking/part1
Last-modified: 17 Feb 1993

This is part 1/2 of the Linux Networking FAQ.

Note that this is still Phil's doc! I just helped with it. I will be uploading
this to tsx-11 and sunsite in a few minutes. -mdw

by Phil Copeland (
Last revision: 17 Feb 1993

quick disclaimer: I must appologize for my luck of a spoll checkr 

0. About this NET-FAQ
	This is the Linux Networking FAQ, which covers all of the details
	of setting up TCP/IP under Linux, either for a network or only
	for loopback mode. It's maintained by Phil Copeland, but this revision
	is by Matt Welsh ( New versions of this doc
	will be posted to comp.os.linux.announce and can be found on the
	major Linux FTP sites such as and

	The version of the kernel used in this NET-FAQ is 0.99.5 and the
	GCC compiler is 2.3.2. Thus, some of these things may or may not
	work depending on your kernel and compiler setup.

	My personal setup is a 486dx-25, 8Mb mem, 105 Mb Scsi Disk,
	Adaptec 1542B Scsi Controller, Generic Scsi Tape (60Mb), 
	1200 Baud Hayes Modem (HP on com2), Inmos B004 transputer board (2Mb),
	Western Digital 8013 16Bit network card, 2 serial ports (com1/4),
	Single printer port and Paradise Pro Designer II SVGA card.

	This mountain of equipment co-exists happily with each other and
	works in harmony with each other. (I only include it here so that
	people realize that such setups can exist)

0.1. A Request
	If you find some text I've written which no longer applies or is a
	complete load of rubarb, please tell me and include a reason or
	corrective text (patch file/ context diff/ off the top of your head
	formats are very welcome)

0.2. Foreward
	This NET-FAQ has grown quite large (~70k) and the past few versions
	contained so much information and were downright confusing. So,
	we revamped it and added a "Quick Start Guide", a quick overview of
	setting up TCP/IP under Linux. It's really quite easy to get
	everything going. There is a lot of reference information here so
	don't be scared off.

1. Introduction

	Hello and welcome to the wonderful world of Linux networking. 

	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 
	which 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 through the network configuration that 
	best suits you, whether you have a single machine with no network 
	attachment (silly I know) or a multi billion credit networking 
	computer for 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 its idiosyncacies.

	As of 21 Jan 93 there is a Linux Networking Quickstart guide (in the 
	next section) by Matt Welsh to help review the process of getting it 
	all going.

1.1. Linux Networking Support
	The Linux kernel is now distributed with the TCP/IP code in it. 
	Basically, Linux's network support is for either UNIX (local)
	domain sockets or INET (TCP/IP) domain. This FAQ specifically
	covers configuring TCP/IP for Linux. You can either configure it
	in "loopback mode" (which allows you to telnet, ftp, etc. only
	to your own machine) or, if you have an Ethernet card, for use
	on a network such as the Internet.

1.2. Supported Ethernet Cards
	To put your machine on a network you need an Ethernet connection
	of some kind and an Ethernet card in your machine. Linux supports
	a number of Ethernet cards, although only the WD8003 and WD8013 (aka
	SMC Elite) cards come with the standard kernel. Donald Becker wrote
	up the following information regarding Ethernet cards, prices, etc.

	The least expensive 8 bit ethercards start at $70 and are usually
	NE1000 clones.  It's definitely worth it to pay an extra $10 and go
	for a 16 bit bus interface NE2000 clone.  For another $10-$15 you can
	get a shared memory 8013 clone, which will give you somewhat higher
	system performance.

	You should expect to pay more than the price I listed above unless you
	do careful shopping from the back of Computer Shopper and (even
	better) LAN magazine.  I've gotten network things from both MCW
	Distributors in Gaitherburg MD (good prices, sort of local, advertises
	in Comp.Shop.) and Network Express (a little more expensive).

	You'll also have to decide the kind of interface you need.  "Thinnet"
	is RG58A 50ohm cable with BNC connectors. 10BaseT is twisted pair
	("TP") to a central "hub".  There is also traditional thick 50ohm
	cable, but it has no advantage in most installations.  An "AUI" port
	is a 15 pin D-shell connector that can be hooked to an external
	transceiver (ca.  $50 for 10BaseT or thinnet), usually for thicknet
	(in which case it's $100+).  Cards typically have an AUI connector and
	either a thinnet or twisted pair transceiver.  You'll pay about $20
	more and give up the AUI to get both thinnet and 10BaseT.

	Some ethercards advertise status LED.  These are most useful for
	10BaseT connections, which are easy to mix up.

	IMHO, thinnet with on-card transceivers results in a _much_ cheaper
	system.  You only need to buy T connectors($3ea.), cables ($6/12ft at
	RS), and two terminators ($2ea.), leading to a per-node cost of under
	$100.  At these price levels it's definitely cheap enough to put on a
	home system!  With twisted pair you'll need a hub which can easily
	double your per-node code.  TP is only cost-effective if the wiring is
	already there and its expensive to run more.

	These drivers support all common 8390-based ethernet boards.  Currently
	"common" is defined as:

2. What you need to get started

	To configure TCP/IP under Linux you need:
	1)	A linux machine with linux kernel 0.98.5 although I'd
		recommend going all the way to 0.99.5 as many tcp/ip errors
		have been stomped out (although not all). 

	2)  	Version 4.2 of the jump table library image (/lib/
		This is needed for the various network binaries and so on.
		The most recent version is on

	2) 	If you're going to use TCP/IP over the network (i.e. not just
		loopback mode), then you need one of the following Ethernet

		SMC Elite 16
		Alta Combo (ne2000 clone)
		Aritsoft LANtastic AE-2 (ne2000 clone w/ extra memory)
		D-Link Ethernet II
		3Com 3c503 EtherlinkII
		3Com 3c503/16
		Cabletron E1010, E1010-x, E2010, E2010-x
		various HP 8390-based boards such as the HP27245, HP27247A,
		  and HP27250

		The wd8003, wd8013, and SMC Elite 16 are all included in the
		standard Linux kernel. The ne2000, ne1000, 3c503, Cabletron,
		HP, and and other 8390 card drivers are available for beta 
		testing. This will be covered later.

	3)	If you are only going to use 'loopback' mode, you won't need
		a card! A special loopback device is used to communicate
		with yourself. 

		*** NOTE when talking of ethernet devices, it should
		be noted that /dev/eth0 does NOT exist, the kernel
		knows about it and thats all you need to know, /dev/eth0
		and /dev/loopback are fictionous (FS speaking)
	4) 	The tcpip-0.8 networking package. This is the old, original
		release of the TCP/IP software. The only things you need
		from this package are the 'config' program and the network
		installation scripts (such as,, and so on).
		Everything else in the tcpip-0.8 package (the kernel code,
		diffs, binaries, etc.) is obsolete.

		You also need the tcpip-0.8-fixes package. You need more or
		less everything from this package: the exact files you need
		are covered later.

		NOTE: If you have SLS you should have everything you need in
		/usr/etc/inet already.

		It's available from all of the major Linux FTP sites, in the
		file tcpip-0.8.tar.Z. The fixes are in tcpip-0.8-fixes.tar.Z.
		They should both be in the same place.

	5) 	The net-bin-0.2 package. It's on sunsite and tsx-11 in the
		file net-bin-0.2.tar.Z. 

		This file contains all of the TCP/IP clients and daemons that
		you'll need, including: telnet, telnetd, ftp, ftpd, inetd,
		named, rcp, rlogin, rsh, talk, ping, nslookup, and more.
	6) 	You don't need the net-lib-1.1 package. The libraries have
		now been added to the most recent, so if you have
		that you're set.

	7) 	If you want NFS support, Linux 0.99 now contains NFS as a
		of mount which lets you NFS mount a filesystem (i.e. mount a
		filesystem on another machine). Look on in

	8)	Know the IRQ's of your internal cards. This is to avoid
		conflicts and allow the 'drivers' to communicate with your

	9)	Also, If you do have ethernet cable, both coax (thin and thick)
		as well as twisted pair will work, the cable is only there to
		carry signals, your ethernet board works out how and the linux
		'drivers' simply stuff data onto the card.

	10)	A lot of coffee and one of those stress relieving 
		gadgets you can get in the local market. [Ed. note: I had
		about 3 Dr. Peppers and I was okay. -mdw]
3. Quick Start Guide to setting up Linux TCP/IP

	This is a rundown of what you need to do to setup TCP/IP. Read it
	through and then keep it all in mind as you're cleaning up all of
	the details below. It's not difficult if you do everything correctly.

	It's not as quick as I wanted it to be. Basically I get all of the
	installation stuff straight and then let Phil explain the details
	of setting up named, etc. later in the NET-FAQ. This section was
	written by Matt Welsh.

	- NOTE: In this discussion, the directory /usr/etc/inet is used 
	  to hold the tcp/ip daemons, configuration files, and so on.
	  You can use ANY directory you want, as long as you're consistent.
	  Two popular alternatives are /etc/inet or just /etc. I like to
	  keep all of my tcp/ip stuff in /usr/etc/inet just to keep it
	  seperate from my other /etc files (because I toy with it a lot).
	  This is mostly personal taste.

	  TCP/IP clients (such as telnet, ftp, and so on) can go anywhere
	  on your user's path. The canonical place is /usr/bin. It doesn't
	  really matter; here I install clients in /usr/bin.

	- (Another) NOTE: Some programs, like fingerd, expect certain files
	  to be in certain places. For example, fingerd won't work if 
	  finger is not in /usr/bin. The easiest solution is to make a
	  symbolic link if you put your clients, etc. elsewhere. If
	  something doesn't seem to be working, make sure everything's
	  in the right place and has correct permissions. One way to
	  find out where a program expects companion programs or files
	  to be is to use 'strings'. For example,
		strings fingerd  | more
	  will show you all of the printable strings in the fingerd
	  binary; you can use this information to find out where fingerd
	  expects finger to be, and so on.

	- First things first: Get all of the files, etc. listed above in
	  section 2.0. When unpacking the tcpip-0.8, tcpip-0.8-fixes, and 
	  net-bin packages, it's helpful to unpack them in separate directories,
	  because we'll be moving the files around to the right places. For 
	  example, unpack tcpip-0.8.tar.Z in /usr/src/tcpip-0.8 and 
	  net-bin-0.2.tar.Z in /usr/src/net-bin (or something like that).

	  NOTE: The current version of SLS (0.99.2 and up) already have
	  pretty much everything you need to get networking going. The
	  configuration files all live in /etc/inet, with /usr/etc/inet
	  being a logical link to this location. So if you have SLS you
	  probably don't need to get all of these files. 

        - Most of the files in tcpip-0.8 you don't need. After you've unpacked
	  it somewhere, take inet.tar and unpack it in /usr/etc/inet (which you
	  may need to create). You can delete the following files in 
          (Don't worry; later we replace them with newer versions).
	- The rest of the files from tcpip-0.8.tar.Z you can delete.

	- Unpack tcpip-0.8-fixes.tar.Z in /usr/etc/inet. You can delete
	  the file 'config' from it.

        - Take the config.c (from tcpip-0.8-fixes) and compile it in 
	  /usr/etc/inet with the command
		gcc -o config config.c

	  NOTE: If you do not recompile config, you will probably get an
	  ioctl error when you reboot with networking installed. To avoid
	  problems, you should recompile the program with the above command.

	- Having unpacked net-bin-0.2.tar.Z in /usr/src somewhere, you
	  can install these binaries. The following files are copied to
		ping (must be setuid root; i.e. do 'chmod 4755 /usr/bin/ping')
		rsh (must be setuid root)
		rcp (must be setuid root)
		rlogin (must be setuid root)
	  The following files are copied to /usr/etc/inet:
	  The man pages are copied to /usr/man... for example, all *.1 are
	  copied to /usr/man/man1 and *.8 are copied to /usr/man/man8.
	- Now you've got all the software installed, you need to recompile
	  your kernel with TCP/IP enabled. This is easy unless you have an
	  old kernel (pre-0.99) or need to install the ne2000/3c503/ne1000
	  drivers. Here's how.

	  IF you're installing the 8390/n2000/3c503/ne1000 drivers (from, directory /pub/linux/newether), follow the directions
	  below for installing the driver. If you're NOT installing the 
	  8390 driver (or only want to use loopback), just skip down to 
	  compiling the kernel.

	  Get the files that you need. See the README's there for full details.
	  Basically you need:
		one or more of ne.c, wd.c, 3c503.c/3c503reg.h, and so on, 
		  depending on the card you have.
		Note that if you have 0.99.pl5 or above you need to get the
		8390.c from /pub/linux/ether-995 instead (as a lot of
		kernel TCP/IP code changed/got better with 0.99.pl5).

	  Just follow the directions found in the file INSTALL on
	  It's easy. Just:
	      - Put the files above in /usr/src/linux/net/tcp.
	      - Edit the GNUmakefile to define which card you have, your
		base address, and your IRQ. Note that with these new
		drivers if EI8390 (the base address) and EI8390_IRQ (the
		IRQ) are defined to be 0, they will be automatically
		detected at bootup time.
              - Edit Space.c (if needed),
	      - If you changed the GNUmakefile to use "eth_if" instead of
		"eth0" (note that the newest 8390 drivers use "eth0" like
		everyone else, they previously used "eth_if"), then you need to 
		edit /usr/etc/inet/ to run $CONFIG on "eth_if" instead of
		"eth0". If not you'll get an ioctl error from config.

    	  If you have problems with the 8390 driver, contact

	- If you're NOT installing the 8390 driver (i.e. just using the wd8003
	  driver with the standard kernel), then you need to edit 
	  /usr/src/linux/net/tcp/Space.c to reflect your card's IRQ, base
	  address, and so on. If you're only using loopback you can skip
	  this step, too.

	  Anyway for those who are flexible, the standard kernel parameters
          for this are :
	      IRQ: 5                  (card interrupt)
	      mem: D0000              (where in memory to buffer data)
	      i/o addr: 280           (low level address of card)
	      mem start: D0000        (nearly all boards have a jumper to
				       set this)
	      mem end: D2000          (for wd8013, make this D4000)
	  NOTE: If you have problems with the memory start addr for the 
	  WD80[0/1]3, please get in touch with

	- Now you're all set to compile the kernel. I really suggest that 
	  you use version 0.99.pl4 or newer (probably 1.0 by the time this
	  is out). If you don't have at least 0.99 you can't run 'make config'
	  to autoconfigure the kernel and you'll have to do some stuff by

	  In any case, it's easy. If you have 0.99 or newer, just cd to
	  /usr/src/linux and do a 'make config'. Make sure you answer 'yes'
	  to the question on configuring TCP/IP. The rest of the options are
	  up to you. Also make sure you edit /usr/src/linux/Makefile to fix
	  your root device, keyboard, and so on.
	  Then do a 'make dep' to fix your dependencies--- THIS
	  STEP IS VERY IMPORTANT. Then (if you've already compiled this 
	  version of the kernel) do a 'make clean'. FINALLY you're ready to
	  just do 'make' to compile the kernel.

 	  When you're done you'll have the new kernel in /usr/src/linux/Image.
	  Copy it to a floppy or install it in /etc for use with LILO, or 
	  whatever. Reboot with your new kernel.

	- Once you're rebooted you can configure the stuff in /usr/etc/inet.
	  Run the script '' there, and answer the questions to
	  set your IP address, net address, router, domain name, and 
	  nameserver. This is covered later in the NET-FAQ.

	  NOTE: If you have SLS then the "" file isn't used. Instead
	  you need to edit hosts, resolv.conf,, and so on by hand to
	  set up the various addresses. It's very straightforward; just make
	  sure that the various configuration files (discussed below) in
	  /etc/inet have the correct information.

	  NOTE 2: If you're only using loopback, then your IP address is
	  "", and you don't have a router, network address, or net
	  mask (these are things prompted for by For SLS,
	  which doesn't have, you just edit the config files
	  in /etc/inet to reflect this. 

	- I had to edit resolv.conf there to make sure that the hostname and
	  domain names were right. No big deal. Under SLS you need to set
	  your hostname in the file /etc/inet/host (not 'hosts') and set
	  the domain name in /etc/inet/domain in addition to this step.

	- Set up your named configuration files. Named is the service that
	  allows your machine to act as a nameserver. If you have a real
	  nameserver already, you probably don't want to run named (wastes
	  memory). If you're on loopback, you don't need it either (just put
	  all of your hostnames and ip addresses in /usr/etc/inet/hosts). 
	  Named is nice if you have a LAN setup and want your Linux box to be 
	  the name server. This is covered in detail later in the NET-FAQ as 

	  In general you don't need to run named unless you really like 
	  hacking with DNS. I don't see any need for it, since you can put
	  all of your hostnames in /usr/etc/inet/hosts and/or consult 
	  another nameserver.
	- Create the file /usr/etc/inet/host.conf. This file tells the
	  name-binding libraries how to look up names: in this case, we're
	  going to tell the libraries to check first /usr/etc/inet/hosts
	  and THEN ask the nameserver (if any). So, create
	  /usr/etc/inet/host.conf. It should contain only these 2 lines:
		order hosts,bind
	  This is VERY IMPORTANT. If you don't create this file then you
	  probably won't be able to look up names as expected. 

	- Set up inetd.conf to include lines for all of the tcp/ip daemons
	  (such as telnetd, fingerd, etc.) that you have in /usr/etc/inet.
	  This is covered later.

	- Make sure that /usr/etc/ is run from your /etc/rc.local.

	- Edit to make sure it's getting your IP address right. As
	  it stands now it tries to grep for it in /usr/etc/inet/hosts,
	  and this doesn't always work. I just hardcode my IP address in since my IP address isn't going to change much. :)

	  SLS also tries to look up your net and router address from 
	  /etc/inet/hosts. I just hardcode these in as well as I don't 
	  trust grep.

	  FOR LOOPBACK ONLY: If you're only using loopback, then edit to make your IP address, and you can ignore
	  the netowkr and router addresses. In, you should only be
	  running the config commands for "loopback", and no others, so
	  comment out the lines which run config on "eth0".

	  If you're using the 8390 driver (see above) make sure you've
	  changed 'eth0' to 'eth_if' on the config commands in

	- If you're not running named, you can comment out the lines which
	  start it in This will save memory and CPU time.

	- If you're not going to run NFS, you can comment out the lines in which run nfsd, mountd, portmapper, and routed. 

	- If you want to use NFS (network file system), you're on your 
	  own. It should suffice to say that you need the nfs-client 
	  stuff from tsx-11 and nfs enabled in your kernel. Should be easy,
	  I haven't played with it yet.

	- If you didn't already, read all of the README files that come
	  with net-bin-0.2 and all that. They contain more up-to-date
	  info. NOTE that the info in tcpip-0.8's README file is mostly
	  out-of-date, follow the directions above and you'll be okay.

	- At this point you should be able to reboot your system, will
	  run, and you'll see something like
		loomer ->
		Starting /usr/etc/inet/inetd
	  which is output from If you don't see this (or if there are
	  errors) then there's a problem; the best way to fix this is to
	  edit and the other files in /usr/etc/inet and make sure you
	  have your IP addresses and everything set right.

	Okay, that's about it for this so-called "Quick Start" guide. the
	rest of the NET-FAQ will fill in the gaps and talk more about
	networking than how to install the softs and configure the kernel.

4. Running

	As mentioned above, to set the various network numbers, etc. 
	for your system you need to run the script, which sets
	lots of things in /usr/etc/inetd (mostly in hosts, resolv.conf, and
	so on).

	NOTE: If you're running SLS you don't have the script.
	Just edit the files discussed in sections 5 and 6 of this net-faq by 
	hand, it's not very difficult. All does is put default
	values in these files for you. 

	NOTE: If you're only on loopback, the only IP address you should
	be using is '' which stands for loopback. You will
	be your own nameserver (either running named or just using 
	/usr/etc/inet/hosts), and you don't need to worry about the router
	and subnetwork addresses.

	When running you'll have to answer these questions:

		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 your 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 since 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.

	There is a convention being used that allows people who are completely 
	bemused by all the ip registration stuff that allocates a band of ip 
	numbers ( which are encouraged to be safely ignored by the 
	rest of the internet. So if you don't know what ip you'll be assigned 
	or (naughty) can't be bothered, please use that range to avoid 
	bringing sections of the internet around your ears.

	IP numbers are typically of the 0-255.0-255.0-255.0-255 range so 
	valid answers are or, etc.  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 were, my 'safe' Net address would be 
	means the whole world and is probably what slip people should 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 with 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 from an ip address of but a machine in the 
	middle with two ip address and can 'collect' 
	the data from the network and transfer it to the network. All we have to do here is stick in the ip 
	address of the local router. You need to find this out from your local
	network admin types. If you don't have a router use meaning 
	don't route anything.
		Enter Domain name for (your host) 
	This isn't too bad, domain names are 'convenient' labels eg is
	the domain name that appends to all the machines on site so that a sun
	called csd would be known as This is so that you don't 
	have to know the full ip number of the host, it's more convenient to 
	call out a semi inteligable name eg = but 
	the 192.35.175 is aliased to (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 '' it can be changed later. 

	mdw: In short the domain name is the name of your ENTIRE domain.
	For instance, my machine is The full hostname
	of the machine is '', and the DOMAIN name is just
	''. Here you're being asked for the DOMAIN name only.
		Name Server for Domain (aaa.bbb.ccc.ddd) 

	If you're on a University or business network, you'll probably have
	a nameserver. A name server just looks up machine names for you.
	For example, if you want to telnet to '', you don't
	have to tell your machine what's IP address is; your
	machine can ask the nameserver instead.

	Ask your local network people what the nameserver for your network is.
	Here you're being asked for the IP address (number) of the machine,
	not the name. If you don't have a nameserver, then just put in your
	own IP address, and you can either run named or go without a nameserver
	(putting all of your names/IP addrs in /usr/etc/inet/hosts).
5. Other /usr/etc/inet configuration files

	Ok time for a quick check of what you minimally *SHOULD* have in 
	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	- 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		- a network rc file called from /etc/rc.local
	services	- a file specifying what 'port' numbers certain 
			  services are available on 
	telnetd		- daemon for accpting incoming telnet requests
	named		- the nameservice daemon 
	Other daemons, such as fingerd, tftpd, and so on.
Time for some explainations I think... 

5.1 config
	'config' is a general do it all 'fix your ethernet board to your
	local setup' command. It was configured when you ran the 
	script and if you look at the 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 provided that your 
	original information was correct. One thing though, I have found that 
	it is best to edit the 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).

5.2 host.conf 
	You'll have to create this file yourself if you don't have it.

	With the new net-libs being made available by Mitch, you will find 
	that it is possible to set up how ip addresses are looked up using the 
	file /usr/etc/inet/host.conf with the entries:

		order hosts,bind

	which tells it in what order it should attempt to resolve an IP/domain 
	name. In this case, when trying to match hostnames & ip addresses, 
	the name binding libraries will search /etc/hosts and if no match is 
	found then query the nameserver).

	If you run named then this is moot; you're your own nameserver. See 
	below about named.

5.3 inetd
	'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 
	communication 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.

5.4 inetd.conf
	Of much more interest is 'inetd.conf' which has information about what
	services to run and where to find them. Here's an example:

# Serv  type    packet wait/nowait      run as  program to run         invoke as
telnet	stream	tcp	nowait		root	/usr/etc/inet/telnetd  telnetd 
talk	dgram	udp	wait		root	/usr/etc/inet/ntalkd   talkd 
echo	dgram	tcp	nowait		root	internal 
ftp	stream	tcp	nowait		root	/usr/etc/inet/ftpd     ftpd -l

	The net-bin-0.2 README file has a list of entries which you may add
	to inetd.conf.  NOTE that inetd.conf cannot have any blank lines in it.
	This is a bug which will be fixed soon.  Also, don't start services
	you don't need or don't understand, like tftpd.  They will only waste
	resources and may have security implications.

5.5 protocols
	Now another file that comes to mind at this stage is /etc/protocols or
	rather /usr/etc/inet/protocols (I've made the symlink 
	/etc/protocols -> /usr/etc/inet/protocols)
	This file contain's information on what protocol is to be used
	when the datagram packet arrives ie how it is to be treated.

	Here's an example /usr/etc/inet/protocols file:

	# protocols - standard well defined IP protocols
	ip	0	# internet protcol, pseudo protocol number
	icmp	1	# internet control message protocol
	igmp	2	# internet group multicast protocol
	ggp	3	# gateway -> gateway protocol
	tcp	6	# transmission control protocol
	egp	8
	pup	12	# PARC universal packet protocol
	udp	17	# user datagram protocol
	idp	22
	raw	255	# raw

	There are others but these are normally never needed.
	(NOTE: the /etc/protocols from the tcpip-0.8 distribution defines ggp 
	to be 2 which isn't the case)

	If this file is missing or empty, you will never get any transports 
	(ftp/telnet) to work and will be told that there isn't any such 

5.6 services
	'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; it is included in the tcpip-0.8-fixes.tar.Z package.
	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.

	Here's a *small* excerpt (not the entire file):

# /usr/etc/inet/services 
tcpmux		1/tcp 		# TCP Port Service Multiplexer 
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 
ftp-data	20/tcp 
ftp		21/tcp 
telnet		23/tcp 
smtp		25/tcp		mail #Simple Mail Transfer 
time            37/udp          timserver 
time		37/tcp	        timerserver	# time 
name		42/tcp		nameserver 
name		42/udp		nameserver 
whois           43/udp          nicname 
whois		43/tcp		nicname 
nameserver	53/tcp          domain 
nameserver	53/udp          domain 

	The other files in /usr/etc/inet are described in the named section

---- end of part 1/2
Matt Welsh, 
  "What are you doing, Dave?"

Newsgroups: comp.os.linux.announce,comp.os.linux,news.answers,comp.answers
Path: sparky!uunet!portal!!caen!batcomputer!theory.TC.Cornell.EDU!mdw
From: m...@TC.Cornell.EDU (Matt Welsh)
Subject: [comp.os.linux] Linux Networking FAQ (Part 2)
Message-ID: <>
Followup-To: poster
Originator: m...@theory.TC.Cornell.EDU
Keywords: Linux TCP/IP Networking
Organization: Cornell Theory Center
Date: Thu, 18 Feb 1993 20:33:34 GMT
Approved: (Matt Welsh)
Lines: 873

Archive-name: linux-faq/networking/part2
Last-modified: 17 Feb 1993

This is part 2/2 of the Linux Networking FAQ. 

6. Names and name servers, what /etc/hosts is all 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' 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 to translate the name into the numeric IP address.

	There are two methods for doing this: one involves using a local lookup
	table ('/usr/etc/inet/hosts') and the other uses DNS (Domain Name 
	System) to remotely interrogate the network for the IP address.

6.1 hosts
	'/usr/etc/inet/hosts' (or /etc/hosts) is a very simple file which 
	contains a numeric IP address followed by one or more hostname

	# /usr/etc/hosts example
	# note that the hash is a comment, no text is processed after 
	# it until the next <cr> 
	#	csd csdsun	manic	# Tom's machine	chef	# Main waste of money 
	# other nets	hal hal-9000		# local hidden host	slave	# linux engine 485 25	zen	# Interactive 2.2.1 386 33	thing 
	# external nets	weird.emer.cty.oz 
	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 

	The SLS /etc/inet/hosts file is more involved, it specifies the
	router, network, and IP addresses. It's pretty self-explanatory
	but you should edit this file (because most everything's set here,
	as isn't used with SLS).

6.2 DNS: Domain Name Service
	DNS 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.
6.2.1 named: running DNS from your own machine
	If you don't have a nameserver (which services DNS requests for you),
	and aren't just using loopback, then you can run named on your own
	machine. Named will allow you to setup a subsection of the DNS database
	for use on your own machine and local network. There are a number of
	files to be edited.

	These are:
		/usr/etc/inet/a_hosts_table (can be called anything, usu.
		  just named.hosts)

	If you have a nameserver, the only file you need is resolv.conf,
	where you define your domain name and nameserver's IP address.
	These are both set up by For example:


	However, if you're going to run named you need to define the
	'nameserver' in resolv.conf to be YOUR OWN IP address. And you need
	to provide information in named.boot and a_hosts_table....


	primary	/usr/etc/inet/a_hosts_table 
	@	IN	SOA root ( 
			1.1	;serial 
			3600	;refresh every 10 hours 
			300	;retry every 6 minutes 
			36000000;expire after 1000 hours 
			3600 )	; default ttl is 100 hours
		IN	NS 
	slave	IN	A   
	hal 	IN	A 
	zen	IN	A 
	mother	IN	A 

	If you're going to run named, resolv.conf, named.boot, and 
	a_hosts_table will suffice, BUT there are more (for other fun named
	options, etc.) 

6.2.2 More complete list of named setup files
	YOU DON'T NEED to run named if you're only using loopback OR if
	you have a nameserver. It's a waste of CPU time and memory. But if
	you don't have a nameserver or if you just feel like hacking it,
	here's a more complete named setup:
	resolv.conf:	If this file exists, it is read each time a process 
			using the resolver starts. As a result, the file is
			not normally created unless necessary and isn't used
			if named is running. You should have it anyway in case
			named dies. :) 
	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.	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) hostcvt
	*** STOP PRESS *** 
	I've just found out from Ross by sheer accident that there is a 
	program released in comp.sources.unix (volume25) called hostcvt (mutter 
	mutter) which is supposidly capable of converting /etc/host entries 
	into the nesessary corrisponding named files. 

	This program is now available on for Linux, in
	/pub/Linux/system/network. It's also distributed on SLS.

	*** RESUME PRESS *** 

6.2.3 Where DNS gets its information
	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 referenced in the primary and the cache 

DNS 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 cache file 
forwarders	|      Lists servers to which queries are forwarded 
slave		|      Forces the server to only use the Forwarders 
	Here are some example setups of the named files.

6.2.4 resolv.conf
	As mentioned before, if you are going to be using named, this file is 
	usually disguarded. Otherwise it points to a server that the resolver 
	is to query for domain information. If no nameserver entries are 
	contained in the file, the local host is queried for the information.

6.2.5 named.boot:
	; cache only server
	primary	0.0.127.IN-ADDR.ARPA	/usr/etc/inet/named.local
	cache	.			/usr/etc/inet/
	The loopback domain is an domain that maps the address 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.
6.2.6 named.boot: 
	; Primary name server boot 
	directory				/usr/etc/inet 
	primary		named.hosts 
	primary		54.152.IN-ADDR.ARPA	named.rev 
	primary		0.0.127.IN-ADDR-ARPA	named.local 
	cache		. 
	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 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 to hostnames. This statement says that the local server 
	is the primary server for the reverse domain and 
	that the data for the domain can be loaded from the file named.rev.

6.2.7 DNS Resource Records (RR's)
	Resource Records are used in the named files to set attributes of
	addresses, networks, and so on. Here's a list of the RR types:

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 
6.2.8 The cache Initialization file 
	The basic '' file contains "NS" records that name the root 
	servers and "A" records tha provide the addresses of the root servers. 
	A basic '' is shown here: 
	; - typical setup 
	; Servers for the root domain 
	99999999	IN	NS 
	99999999	IN	NS 
	; Root servers by addresses 
	;	99999999	IN	A	99999999	IN	A 
	Note that the ttl is 99999999 the largest possible size so that the 
	root servers are never removed from the cache.
6.2.9 The 'named.local' file 
	The 'named.local' file is used to convert the address (the
	loopback address) into the name localhost. It's the zone file for the
	reverse domain Because ALL systems use 
	as the loopback address, this file is virtually identical on every 
	@	IN 	SOA root. ( 
				1	;	serial number
				36000	;	refresh every 10 hrs 
				3600	;	retry after 1 hr 
				3600000	;	expire after 1000 hrs 
				36000	;	default ttl is 10 hrs 
		IN	NS 
	1	IN	PTR	localhost. 
6.2.10 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       probs. (
				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 
		IN	MX 
	; define localhost
	localhost	IN	A 
	;hosts in this zone 
	loghost		IN	A
	hal		IN	A 
	zen		IN	A 
	thing		IN	A 
	slave		IN	A 
			IN	MX	2 
	servant		IN	CNAME 
	mother		IN	A 
	; outside domains now follow 
	csd		IN	A 
			IN	MX	5 
	csdsun		IN	CNAME 
	chef		IN	A 
	;fictional outside gateway 
	midway		IN	A 
	; etc until you have built a reasonable host table 
	; that you feel will be adaquate for your network 
7. NFS: The Network File 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 has several benefits:
	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 accessible to everyone
		on the network. 
	2)	NFS simplifies central support tasks, because 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.

	As of 0.99.2 support has been added into the kernel for running
	binaries on both the MSDOS and NFS filesystems (of course the
	binaries have to be Linux type binaries to run on your system).
	Linus warns that they'll be slower to load and won't be memory
	effecient; there are hopes that this will change soon.
	Linux now has the following filesystems available for it: minix, 
	extfs, msdos, proc, isofs, nfs with a view to a compressed 
	filesystem being worked on (zfs?) all are perfectly transparent to 
	each other although filename tructation may occur. The reason that I 
	mention this is that NFS will allow you filename lengths supported by 
	the type of filesystem you mount eg the HP9000 here supports 15 char 
	filenames on an NFS mount as does it's MAG-OPT drive whereas the 
	sun4's offer 255 char filename on their NFS exports.

7.1 The '/etc/exports' file
	If you want your machine to be an NFS server for other systems,
	you must run nfsd, mountd and edit /etc/exports.

	'/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): 
	/	slave(root_quash) moonbeam(root_quash)
	/usr	(ro,root_quash)
	/home	slave csdsun 
flag	|	function 
ro	|	read only, this is the default
rw	|	read and write, used to allow a client to write to that FS
	There are other options but these are covered in the README for the 
	NFS kit and the above are the simplest to get to grips with.
7.2 The /usr/etc/inet/ file 
	The file '' is used to start the named services and nfs the 
	suggested setup is as follows:
	if [ -f /etc/portmap ] 
        	echo "Starting portmapper..." 
		if [ -f /etc/exports ]
			echo "Starting nfsd..." 
			echo "Starting mountd...." 
		mount -vt nfs fish:/pub /pub & 
		mount -vt nfs sparky:/mnt/a /test & 
	Here if the portmapper isn't running it is started. Once started, it 
	is now possible to 'hang' the nfsd daemon as well as the mountd daemon 
	off it.  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.

8. '...And on the 6th day she said, "let there be connectivity"...'

	All this is well and fine but shows nothing of how to use the various 
	utilities commonly taken for granted in networking. ie telnet & ftp 
	and X11. 
8.1 telnet	
	Normally people would telnet over a LAN (Large area network) 
	to a remote site simply to play a mud (multi user dungeon) which runs 
	on a socket say port number 4000 so the command 'telnet 4000' would connect to a service offered by that 
	machine on port 4000. Now then, sockets are most easily perceived as 
	'openings' in a wall where data may pass through in a uni/bidirectional 
	fashion, there are any number of ports available for use and quite a 
	few reserved port sockets can be found in your /etc/services file. 
	For example by telneting to port 7 of your target machine you should 
	be able to communicate with the computer by typing in a few charcters 
	and pressing return. Port 7 is the echo service and any input you type 
	should be sent back exactly as you sent it. In normal use, however, 
	telnet connects to port 23 where a login service is provided for 
	interactive logins to the system.

	The canonical usage of telnet is just 
		telnet <hostname> 
	where <hostname> is another machine on the net that you want to
	log into.

8.2 ftp
	Ftp allows the user to transfer files from the host to the target
	machine but requires the user to login as (s)he would normally. Once 
	logged in the user can transfer files both into and out of the machine 
	with simple commands like 'get text.doc' or 'send report.wps'. Ofter 
	ftp is used in the 'get' mode and when browsing sites it is usefull to 
	know that you can peek at the contents of a small README file using 
	the command 'get README.requirements /dev/tty' which will transfer the 
	contents of the file to your tty line (in english: the screen)

	To start up FTP, just do
		ftp <hostname>
	where <hostname> is the machine you want to upload/download from.
	For public FTP service, login on the remote machine as "anonymous"
	and give your e-mail address as the password.

8.3 X11 and networking
	After you have networking set up, you can now run X Windows across the 
	network. For example, you can login to a remote machine in one xterm, 
	and from that machine run an X program and direct it to display on 
	your machine. For example, if your Linux machine is called "shoop", on 
	the remote machine the command 
		xclock -display shoop:0 &
	would display the clock on shoop's display.

	Before you can do this, however, you must run the command "xhost" on
	shoop to allow the remote machine to display on shoop. If the
	remote machine is "loomer", from shoop you must run the command	
		xhost loomer
	to give loomer this access.

	This is the entire concept underlying X Windows: you can now run huge
	programs (such as Mathematica) on remote machines and have them
	display on your Linux box. 

9. Standalone named Configuration

	What follows is an example named configuration for a local (2-machine)
	isolated network. 

	Well after some peer pressure, I see that I'm going to have to include a
	standalone configuration in the FAQ as well. According to my 
	sources/hallucinations, there is an accepted address that is for 
	'junk' setups so as not to conflict with other machines on the 
	internet. That address is where xxx ranges 0..255. 
	(This address is not routed through the internet so you should be 
	relatively safe from ip address clashes).

	I'm going to assume that your configurations will be held in /etc so 
	the following files will be referanced there instead of /usr/etc/inet 
	or /etc/inet. (NOTE: This deviates from the discussion above. /etc
	is fine to use instead of /usr/etc/inet as long as you're

	A while ago I posted a couple of messages concerning the setup
	of the named daemon config. files for a simple isolated 
	network with a local nameserver. Since nobody responded with
	a ready-to-go solution I decided to dig a little deeper into
	the subject. As a result I've now got a working nameserver.
	This message describes the changes I made. Here goes:

9.1 General Info
	My isolated network consists of 2 machines, called whisky
	and jenever which are both located in the domain vdm. Whisky
	has IP address and jenever has IP address
	The nameserver runs on whisky, and jenever accesses whisky to
	resolve names.

	Starting point is SLS 0.98pl5. This distribution contains and hostcvt, which are supposed to make network
	installation easier, but they where of no help to me. Instead,
	I manually changed the files concerned.

9.2 Common changes to files for both machines.
	/bin/hostname machine_name added to /etc/rc. Machine_name
	stands for either whisky or jenever. This command should
	be placed before the /bin/sh rc.local command. Further 
	hostname commands removed from /etc/rc and /etc/rc.local.

	In /etc/inet/ HOSTNAME=softland changed to 
	HOSTNAME=machine_name. Commented out the IPADDR= line 
	and inserted IPADDR= or IPADDR=

	ROUTER set to and NET set to In the
	third $CONFIG line eth0 changed into eth_if (I use an
	Artisoft network card, this isn't necessary for standard
	WD network cards).

9.3 Changes for the nameserver (whisky in my case).
	For a nameserver the portmap, inetd and named daemons
	should be started. This is done in the /etc/

	named.boot contains 
	directory	/etc

	domain		vdm
	primary		vdm			named.hosts
	primary	named.rev
	primary	named.local

	named.hosts contains
	@	IN   SOA  whisky.vdm.  root.whisky.vdm. (
			  1    ; Serial
			  3600 ; Refresh
			  300  ; Retry
			  3600000   ; Expire
			  14400 )   ; Minimum

		IN	NS	whisky.vdm.

	localhost	IN	A
	whisky		IN	A
	jenever		IN	A

	named.rev contains
	@	IN	SOA	whisky.vdm. root.whisky.vdm. (
				1 ;
				3600 ;
				300 ;
				3600000 ;
				3600 ) 

		IN	NS	whisky.vdm.

	1	IN	PTR	whisky.vdm.
	4	IN	PTR	jenever.vdm.

	named.local contains
	@	IN	SOA	whisky.vdm.	root.whisky.vdm. (

		IN	NS	whisky.vdm.
	1	IN	PTR	localhost.
9.4 Changed for a non-nameserver (jenever in my case).

	For a non-nameserver only the portmap and inetd daemons
	have to be started. The startup of the named daemon in
	/etc/inet/ can thus be commented out.
	A non-nameserver depends on a nameserver for name
	resolution. The non-nameserver is directed to a name-
	server by the /etc/resolv.conf file (NOT the
	/etc/resolv.conf as mentioned in a lot of doc. files).
	So, the /etc/inet/resolv.conf file on jenever contains:
	domain vdm
	That's all. 

10. Troubleshooting and Common Problems

	Here are some of the most common problems with Linux tcp/ip.

10.1 config
	One of the most common complaints regards the 'config' command.  What 
	isn't often noted is that this has to be recompiled from the 0.8.1 
	sources (available currently as

10.2 Library versions
	Another problem that crops up is that some binaries that are 
	distributed require libc.2.2.2 to be present (i.e. the telnet and
	ftp in tcpip-0.8. ONLY use the binaries in net-bin-0.2 or a newer
	version (which use jump-4.2 or newer) and you're okay.

	Other people think that it's their version of libraries that cause the
	problem but can't find the source code for the various utils to 
	recompile. Get the net-src-0.2.tar.Z package from sunsite or tsx-11
	and you're set; recompile at will. :)

10.3 kernel errors
	You boot the new kernel and suddenly all hell breaks loose... you 
	have printk's telling you about RPC errors, framepacket errors etc... 
	it looks a mess but the kernel keeps working... I suggest you grab 
	HLU's bootdisk and edit your rc files again. Your problem here is most 
	likely that you have accidentally attemped to use a working IP address 
	as your own. If it's a sun's, you can expect the sun to lose all 
	networking capabillity and not recover until lots of drastic commands 
	are issued (fastboot won't help the guy either). I was asked to do 
	this so I wasn't too fussed but loads os system admin people out there 
	will get very ticked off if you do this deliberately.

10.4 named problems
	To check that something is working in named when it is run check out
	/usr/tmp/named_dumb.db. This is the file that named creates from all 
	your configuration files. Check it exists, and contains formatted 
	information similar to your named.hosts file. If it's zero length then 
	something is wrong with your SOA record heading (A missing '.' perhaps).

10.5 More than one ethernet card in the machine, IRQ conflicts
	If you have more than one Ethernet card in your machine OR you have
	a device sharing the IRQ of your network card, you may have problems.
	Try pulling one of the cards and see what happens, or changing the
	IRQ (usually done with jumpers on the card).

	In the Linux kernel source, net/tcp/Space.c defines the network
	devices to configure. I hear that if you use the 8390/ne2000 driver
	on IRQ 5, the entry for the wd8003 card in Space.c will confuse things;
	thus just change the #ifdef around the wd entry in Space.c to something
	else so it's not compiled in.

	The following is provided by Ross Biro.

	If you get the message about time outs on the interrupt, you probably
	have your irq configured incorrectly.  The irq in Space.c (default 5)
	MUST match the one on your card. 

	If nothing happens when you try to use an interface, check the irq
	and try to get a new copy of config.  Some versions fail to mark the
	interface as up (the config.c in tcpip-0.8-fixes should work).

	If you get messages about large packets and immpossible sizes to malloc,
	you have the memory on your card configured incorrectly, or there is a
	conflict with some other piece of hardware.  Fix this by checking that
	your memory is configued right in Space.c and if it still fails, try
	ALL possible locations in memory (people have suggested that higher
	seems to work better.)

	If you get a message about runt packets, you can safely ignore it 
	and/or comment the printk (kernel debugging output function) out of 
	we.c.  It indicates either a hardware problem or a initialization 
	problem in we.c. It only seems to occur on some versions of the SMC 
	Elite and there is other code to deal with the problem.

	Also Note if it works under DOS does NOT mean there is not a hardware
10.6 General ideas
	Now then, to give you an idea of what is possible, I'll describe what
	I have setup and working. I have X11(Xfree86-1.2) running... In one 
	xterm I have a dos session going, in another I have a telnet session 
	connected to a sun (csd), and on that sun, i'm connected to a diku on 
	the linux machine through 'telnet slave 4000', in yet another xterm I 
	have an ftp session to yet another sun(chef) pulling CIA 10Megabugger 
	world map onto an NFS mounted disk on another sun (hal) at a rate of 
	about 35k/s (+/- 15k). I was going to mount up a swapfile on an NFS 
	disk but decided against it on the grounds of what might happen if the 
	external machine fell over while I was using that swapfile.

	Some relief can be found on the newsgroup/mailing lists but one thing 
	that will *REALLY* help is this...

	#include <sanity.h>
	#include <sys/coherance.h>
	#include <sys/commonsence.h>

	char	alpha_test[1..80];
	FILE	*panic;

	if ((kernel == lastest_on_offer) && (tcpip_broke))
		if (kernel_paniced)
			fprintf(std_email,"give blurb about kernel\n");
			system("nm ~linux/tools/system | grep <addr_of_err>");
			fprintf(std_email,"Conditions of error (recreatable)");

	(Sorry about that, we had a compitition to find out who could write 
	the whackist pseudo C code) more simply stated, the error address that 
	is reported by the kernel can be used with a kernel system file to 
	tell us what function broke and how far into it it broke. See below 
	for more on that:

Several things that can help

	1)	Upgrade your kernel to the latest one that you can grab  
		(currently at time of writting 0.99.4). Alternatively
		if you are running 0.98.5, all the patches are available
		on, but
		as always, think strongly of going to a higher kernel
		version as they nearly alwas have all the patches applied
		for tcpip and other misc stuff.

	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 2.3.3 if possible.

	4)	Binary distributions of various network probrams can be 
		found on,.. always read the README files 
		they are there for a reason! (personal show/contacts/etc..) and also have good variation
		in utilities that you can use. Also don't forget that a lot
		of network programs will compile reasonably well although,
		be prepared for unexpected weeks of fustration.

	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)	If you are experiencing problems with missing files which are
		placed where you think they *should* be, it's always worth
		trying the following to find out what files are being used

			strings <prog> | less
		This should show up any hard linked files in the binary.
		eg differing versions of telnet will look at /etc/services OR
		/usr/etc/inet/services, therefore, it is a good idea to have
		a symlink from one to the other eg

			ln -s /etc/services /usr/etc/inet/services

	7) 	If the kernel panics, jot down the address next to EIP. Then do
	   	an 'nm /usr/src/linux/tools/system | sort -n' and find out what
	   	function the given EIP address is in. This will help a lot. If 
		you simply post the panic message to the newsgroup, everyone's 
		kernel is different so it doesn't tell us much.

	7)	Complain bitterly to me if I haven't covered your problem  
		and I'll get it sorted for the next NET-FAQ.
11. 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 DeSouza	-	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 code in the 
			kernel.  He also ported the NFS server and the RPC 

Donald Becker	-	Author of the drop in drivers for the linux kernel
			allowing the following cards to be used,
			3com503, 3com503/16, NE2000, NE1000 and even a
			3com501 (Donald: 'not recommended').

Matt Welsh	-	Trashed, er... reformatted this document, tried 
			to clean it up. Wrote the tcp/ip quick start guide and 
			answers tcp/ip config questions.
The pioneers	-	These are the fearless people who brazenly marched 
			their filesystems towards complete oblivion and 
			watched weeks of work evapourate in milliseconds 
			without a shred of hate for the OS that they had come 
			to love.
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 with the various bug reports that
			inevitably crop up. 
Linus Torvalds	-	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. 
The critics	-	For reminding me that it's a thursday... I never
			could get the hang of thursday's...

Myself (Phil)   -	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 veteran?) 
Phil	(The non spell checking insomniacial/palagerist who never learnt 
=--=	 english grammer) 

Matt Welsh, 
  "What are you doing, Dave?"

			  SCO's Case Against IBM

November 12, 2003 - Jed Boal from Eyewitness News KSL 5 TV provides an
overview on SCO's case against IBM. Darl McBride, SCO's president and CEO,
talks about the lawsuit's impact and attacks. Jason Holt, student and 
Linux user, talks about the benefits of code availability and the merits 
of the SCO vs IBM lawsuit. See SCO vs IBM.

Note: The materials and information included in these Web pages are not to
be used for any other purpose other than private study, research, review
or criticism.