62. Sharing a folder between computers using nfs on Debian

A year ago I posted about getting nfs set up for a local network as part of a longer post -- here it is reposted, with minimal changes to make up for the substitution of portmap for rpcbind in debian. Hopefully it'll be clearer. Also, nfs is such a universally useful thing that it should be promoted among a wider audience.

I followed this post to get up and running (scroll down) with nfs. Here's my take on it:

UPDATE: with the first comment below in mind, I changed this post a little bit. The folder /shared on the master node is shared with the client, which mounts it under /home/me/shared, instead of sharing the folder /home/me/shared on the host and mounting it as /home/me/shared on the client. I basically want to drive home the message that you're mounting an NFS share in the same way as any other disk resource -- you can mount it in whatever location you want, regardless of where the folder is found on the host.

Server
On the master node (here: 192.168.1.1 - beryllium) which hosts the shared folder on its harddrive:
sudo apt-get install nfs-kernel-server nfs-common rpcbind

Let's share /shared

Create it
sudo mkdir /shared

Set permissions for 'all' to be read, write and execute
sudo chmod a+wrx /shared

Edit /etc/exports by adding a line to the end of the file
/shared *(rw,sync)



[Note that this (the *) is inherently insecure. You should restrict access to the NFS mounts via your firewall (e.g. using iptables with -A INPUT -s 192.168.1.0/24 -p udp -m udp --dport 2049 -j ACCEPT;  -A INPUT -s 192.168.1.0/24 -p udp -m udp --dport 111 -j ACCEPT for a local subnet 192.168.1.1-255).  You can also use 
/shared 192.168.1.0/24(rw,sync)

to restrict it similarly directly via /etc/exports. There are more things that can be done, see e.g. here and here. If you are running a cluster with a separate subnet, this is not a great worry. If you are in a situation where security is important, consider using sshfs instead.]

Make stuff happen:
sudo /etc/init.d/nfs-kernel-server restart
sudo exportfs -a

Client
On each client node:
sudo apt-get install rpcbind nfs-common
mkdir ~/shared

Add the following line to the end of /etc/fstab
beryllium:/shared /home/me/shared nfs   rw   0   0

You can mount in a different location if needed -- server:serverfolder localfolder nfs rw 0 0

To get it up and running immediately instead of waiting for reboot:
sudo mount ~/shared


That's it!

---

Links to this page:
http://forums.debian.net/viewtopic.php?f=5&t=84889

61. Keeping time with ntp on debian

Set-up
NTP is used to accurately sync the clock on your computer and keep it current.

Install ntp if you haven't already
sudo apt-get install ntp ntpdate
the configuration file is in /etc/ntp.conf

You can have a look through the ntp.conf file and change the server lines to something closer to home if necessary -- you can find server pools for different regions here: http://www.pool.ntp.org/en/

If your clock is off by too much, syncing won't work, so you might want to do this to sync up the first time:

sudo service ntp stop
sudo ntpdate -u 0.pool.ntp.org

 8 Feb 16:28:42 ntpdate[10484]: step time server 121.0.0.41 offset -648.353916 sec

compare the output of date with e.g http://worldtimeserver.com

Now, start the ntp server again:

sudo service ntp start

Running your own local ntp server for your LAN

The NTP daemon will (presumably) run happily in the background and gradually adjust the time if it's off.

For a sub-LAN  you may want to sync e.g. the gateway to the ntp pool, then sync all the local computers to the gateway in order to cut down on traffic, like so.

Here's my version of that link:

server:

Here's /etc/ntp.conf on my server, which is seen as 192.168.1.1 by the local subnet (connected to inet on eth0 and subnet on eth1) . The last two lines were important to get it to work.

driftfile /var/lib/ntp/ntp.drift
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
server 0.oceania.pool.ntp.org
server 1.oceania.pool.ntp.org
server 2.oceania.pool.ntp.org
server 3.oceania.pool.ntp.org
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery
restrict 127.0.0.1
restrict ::1
restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
broadcast 192.168.1.255
server 127.127.1.0
fudge 127.127.1.0 stratum 10

sudo service ntp restart

and you're good to go

client:

/etc/ntp.conf

driftfile /var/lib/ntp/ntp.drift
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
server 192.168.1.1
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery
restrict 127.0.0.1
restrict ::1
restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
disable auth
broadcastclient

sudo service ntp restart

Checking if the client is connecting to the server.

me@kookaburra:~$ sudo service ntp stop
Stopping NTP server: ntpd.
me@kookaburra:~$ sudo ntpdate 192.168.1.1
 8 Feb 17:22:35 ntpdate[12846]: adjust time server 192.168.1.1 offset -0.008602 sec
me@kookaburra:~$ sudo service ntp start
Starting NTP server: ntpd.
me@kookaburra:~$ sudo ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 beryllium       LOCAL(0)        11 u    2   64    1    0.189   -7.332   0.000

(beryllium is the name of my 192.168.1.1 server.)

60. i18n_translation and no Package:Header error on Debian Testing 32 bit

I'm doing this via an apt-cache server (i.e. the 192.168.1.1 rather than ftp.au.debian.org) -- but the problem is unrelated to the apt-cache server.

Symptom:

Get:1 http://192.168.1.1 testing InRelease [179 kB]
Ign http://192.168.1.1 testing/contrib TranslationIndex
Get:2 http://192.168.1.1 testing/main TranslationIndex [2,154 B]
Ign http://192.168.1.1 testing/non-free TranslationIndex
Get:3 http://192.168.1.1 testing/main i386 Packages [7,146 kB]
Get:4 http://192.168.1.1 testing/contrib i386 Packages [48.9 kB]
Get:5 http://192.168.1.1 testing/non-free i386 Packages [87.5 kB]
Ign http://192.168.1.1 testing/contrib Translation-en_AU
Get:6 http://192.168.1.1 testing/contrib Translation-en [34.8 kB]
Get:7 http://192.168.1.1 testing/main Translation-en [3,722 kB]
Ign http://192.168.1.1 testing/non-free Translation-en_AU                                
Get:8 http://192.168.1.1 testing/non-free Translation-en [62.5 kB]
Fetched 11.3 MB in 2s (4,348 kB/s)                                                          
W: Failed to fetch copy:/var/lib/apt/lists/partial/192.168.1.1:3142_ftp.au.debian.org_debian_dists_testing_main_i18n_Translation-en  Encountered a section with no Package: header

E: Some index files failed to download. They have been ignored, or old ones used instead.

Reason:
ftp://ftp.au.debian.org/debian/dists/wheezy/main/i18n/
All the files in that directory are compressed (bz2) -- you need to enable apt-get to decompress .bz2 files.

Solution:
Install bzip2

sudo apt-get install bzip2

at this point gives

Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/192.168.1.1:3142_ftp.au.debian.org_debian_dists_testing_contrib_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.

So remove the offending files (2 lines):

sudo rm  /var/lib/apt/lists/192.168.1.1:3142_ftp.au.debian.org_debian_dists_testing_contrib_i18n_Translation-en

sudo rm /var/lib/apt/lists/192.168.1.1:3142_ftp.au.debian.org_debian_dists_testing_non-free_i18n_Translation-en

Now you can 

sudo apt-get install bzip2

followed by

sudo apt-get update

Hit http://192.168.1.1 testing InRelease
Get:1 http://192.168.1.1 testing/main i386 Packages/DiffIndex [2,038 B]
Get:2 http://192.168.1.1 testing/contrib i386 Packages/DiffIndex [2,023 B]
Get:3 http://192.168.1.1 testing/non-free i386 Packages/DiffIndex [2,023 B]
Ign http://192.168.1.1 testing/contrib TranslationIndex
Hit http://192.168.1.1 testing/main TranslationIndex
Ign http://192.168.1.1 testing/non-free TranslationIndex
Get:4 http://192.168.1.1 testing/contrib Translation-en [34.8 kB]
Get:5 http://192.168.1.1 testing/main Translation-en [3,722 kB]
Get:6 http://192.168.1.1 testing/non-free Translation-en [62.5 kB]
Ign http://192.168.1.1 testing/contrib Translation-en_AU        
Ign http://192.168.1.1 testing/non-free Translation-en_AU
Fetched 103 kB in 4s (25.3 kB/s)
Reading package lists... Done

Done indeed!