Before you continue reading this HOWTO you will need to be able to telnet back and forth between the machine you're using as server and the client. If that does not work you need to check the networking/NET-3 HOWTO and set up networking properly.
Before we can do anything else we need a NFS server set up. If you're part of a department or university network there are likely numerous NFS servers already set up. If they will let you get access to them, or indeed, if you're reading this HOWTO to get access to one of them you obviously don't need to read this section and can just skip ahead to the section on setting up a NFS client
If you need to set up a non-Linux box as server you will have to read the system manual(s) to discover how to enable NFS serving and export of file systems through NFS. There is a separate section in this HOWTO on how to do it on many different systems. After you have figured all that out you can continue reading the next section of this HOWTO. Or read more of this section since some of the things I will say are relevant no matter what kind of machine you use as server.
If you're running please see the Linux 2.2 section before you continue reading this.
Those of you still reading will need to set up a number of programs.
The portmapper on Linux is called either portmap or
rpc.portmap. The man page on my system says it is a "DARPA port
to RPC program number mapper". It is the first security hole you'll
open reading this HOWTO. Description of how to close one of the holes
is in
the security section. Which I,
again, urge you to read.
Start the portmapper. It's either called portmap or
rpc.portmap and it should live in the /usr/sbin
directory (on some machines it's called rpcbind). You can start it by
hand now, but it will need to be started every time you boot your
machine so you need to make/edit the rc scripts. Your rc scripts are
explained more closely in the init man page, they usually reside in
/etc/rc.d, /etc/init.d or /etc/rc.d/init.d.
If there is a script called something like inet it's probably the
right script to edit. But, what to write or do is outside the scope
of this HOWTO. Start portmap, and check that it lives by running
ps aux and then rpcinfo -p. It does? Good.
Oh, one thing. Remote access to your portmapper is regulated by
the contents of your /etc/hosts.allow and
/etc/hosts.deny files. If rpcinfo -p fails, but your
portmapper is running please examine these files. See
the security section for details on these
files.
The next programs we need running are mountd and nfsd. But first
we'll edit another file. /etc/exports this time. Say I want
the file system /mn/eris/local which lives on the machine
eris to be available to the machine called apollon.
Then I'd put this in /etc/exports on eris:
/mn/eris/local apollon(rw)
The above line gives apollon read/write access to
/mn/eris/local. Instead of rw it could say ro
which means read only (if you put nothing it defaults to read only).
There are other options you can give it, and I will discuss some
security related ones later. They are all enumerated in the
exports man page which you should have read at least once in your
life. There are also better ways than listing all the hosts in the
exports file. You can for example use net groups if you are running
NIS (or NYS) (NIS was known as YP), and always specify domain wild
cards and IP-subnets as hosts that are allowed to mount something.
But you should consider who can get access to the server in
unauthorized ways if you use such blanket authorizations.
Note: This exports file is not the same syntax that other Unixes
use. There is a separate section in this HOWTO about other Unixes
exports files.
Now we're set to start mountd (or maybe it's called rpc.mountd
and then nfsd (which could be called rpc.nfsd). They will both
read the exports file.
If you edit /etc/exports you will have to make sure nfsd
and mountd knows that the files have changed. The traditonal way is
to run exportfs. Many Linux distributions lack a exportfs
program. If you're exportfs-less you can install this script on your
machine:
#!/bin/sh killall -HUP /usr/sbin/rpc.mountd killall -HUP /usr/sbin/rpc.nfsd echo re-exported file systems
Save it in, say, /usr/sbin/exportfs, and don't forget to
chmod a+rx it. Now, whenever you change your exports file, you
run exportfs after, as root.
Now you should check that mountd and nfsd are running properly.
First with rpcinfo -p. It should show something like this:
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100005 1 udp 745 mountd
100005 1 tcp 747 mountd
100003 2 udp 2049 nfs
100003 2 tcp 2049 nfs
As you see the portmapper has announced it's services, and so has mountd and nfsd.
If you get rpcinfo: can't contact portmapper: RPC: Remote
system error - Connection refused,
RPC_PROG_NOT_REGISTERED or something similar instead then the
portmapper isn't running. OR you might have something in
/etc/hosts.{allow,deny} that forbids the portmapper from
answering, please see
the security section for details on these files. If you get No remote
programs registered. then either the portmapper doesn't want to
talk to you, or something is broken. Kill nfsd, mountd, and the
portmapper and try the ignition sequence again.
After checking that the portmapper reports the services you can check with ps too. The portmapper will continue to report the services even after the programs that extend them have crashed. So a ps check can be smart if something seems broken.
Of course, you will need to modify your system rc files to start mountd and nfsd as well as the portmapper when you boot. It is very likely that the scripts already exist on your machine, you just have to uncomment the critical section or activate it for the correct init run levels.
Man pages you should be familiar with now: portmap, mountd, nfsd, and exports.
Well, if you did everything exactly like I said you should you're all set to start on the NFS client.