Difference between revisions of "Linux Installation"

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The original kernel shipped with Debian sarge has a broken serial driver for Ultra 5s.  The version in the security updates should work.
 
The original kernel shipped with Debian sarge has a broken serial driver for Ultra 5s.  The version in the security updates should work.
 
== Getting user information from [[LDAP]] ==
 
 
The <code>libnss-ldap</code> package handles fetching account information from LDAP.
 
Also make sure that <code>nscd</code> is installed, otherwise [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=190072 bad things] may happen.
 
 
To tell <code>libnss-ldap</code> where to look, you need to edit
 
the <code>/etc/libnss-ldap.conf</code>.  At the very least, you'll need to
 
give the host and base (<code>dc=tardis,dc=ed,dc=ac,dc=uk</code>).
 
 
To tell libc to use <code>libnss-ldap</code>, you need to amend the appropriate lines in <code>/etc/nsswitch.conf</code>:
 
<pre>
 
passwd:        files ldap
 
group:          files ldap
 
shadow:        files ldap
 
</pre>
 
The other databases are best left alone; we don't bother putting host
 
information or such like in LDAP because we don't see much benefit.
 
 
The <code>getent</code> program is useful for testing.
 
 
== Authenticating with [[LDAP]] ==
 
 
The <code>libpam-ldap</code> package is used for authentication against LDAP.  You need to configure <code>/etc/pam_ldap.conf</code> along the same lines as <code>/etc/libnss_ldap.conf</code>.  A typical example is:
 
<pre>
 
host piper
 
base dc=tardis,dc=ed,dc=ac,dc=uk
 
rootbinddn cn=admin,dc=tardis,dc=ed,dc=ac,dc=uk
 
ldap_version 3
 
 
# NSS lookups need to be restricted to the appropriate parts of the tree.
 
# If other lookups are added to /etc/nsswitch.conf, they need to be put
 
# here too.
 
nss_base_passwd ou=People,dc=tardis,dc=ed,dc=ac,dc=uk
 
nss_base_group  ou=Group,dc=tardis,dc=ed,dc=ac,dc=uk
 
nss_base_shadow ou=People,dc=tardis,dc=ed,dc=ac,dc=uk
 
 
# Use funky generic LDAP password changing.
 
pam_password exop
 
</pre>
 
 
PAM needs to be told to use <code>libpam-ldap</code>, as well as the normal authentication for <code>root</code>.  Canonical <code>/etc/pam.d/common-auth</code>:
 
<pre>
 
# ** Use trick from /usr/share/doc/libpam-ldap/README.Debian
 
#
 
auth    [success=1 default=ignore]      pam_unix.so nullok_secure
 
auth    required                        pam_ldap.so use_first_pass
 
auth    required                        pam_permit.so
 
</pre>
 
Note the <code>use_first_pass</code> option.  Without it logins will ask for a password for pam_unix, then one for pam_ldap, and so on, causing every other attempt to enter your password to fail even when you get it right.  You need to set up <code>/etc/pam.d/common-account</code> in the same way.
 
  
 
=== Restricting access to admins ===
 
=== Restricting access to admins ===

Revision as of 19:19, 10 July 2007

Serial console

If the machine is only providing serial output during bootup, then it may not have been configured for serial logins. Check that the /etc/inittab file contains a line like

T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100

which tells init to start the program to provide login prompts.

The original kernel shipped with Debian sarge has a broken serial driver for Ultra 5s. The version in the security updates should work.

Restricting access to admins

In /etc/security/access.conf add

+:ALL:cron
-:ALL EXCEPT root admin:ALL

[Hmmm... maybe that should be LOCAL instead of cron.]

Ensure that /etc/pam.d/common-account ensure that the pam_access module is used to restrict access. For example,

account [success=1 default=ignore]      pam_unix.so debug
account required                        pam_ldap.so debug
account required                        pam_access.so

Multiple VLANs

Some systems need to appear on several VLANs, most notably the router. First, add

8021q

to the end of /etc/modules so that the kernel knows how to deal with the VLAN tagged packets. (Use modprobe 8021q to load it immediately if you don't want to reboot.) Then install the vlan Debian package, and add extra stanzas to /etc/network/interfaces for the new VLANs. For example,

# Admin VLAN
auto eth0.1
iface eth0.1 inet static
        address 192.168.1.6
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255

where eth0.1 means VLAN number 1 on interface eth0. Finally, configure the switch so that the port is on the extra VLANs.

Logging to the Log host

To make syslog send logs to the log host, put

*.*     @loghost

into /etc/syslog.conf. It is a good idea to keep the local logging too, in case of network problems.

Email config

Install the exim4 package and execute 'dpkg-reconfigure exim4-config' to configure it with the details below:

Split configuration into small files:                      NO
General type of mail configuration:                        mail sent by smarthost; no local mail
System mail name:                                          HOSTNAME.tardis.ed.ac.uk
IP-addresses to listen on for incoming SMTP connections:   127.0.0.1
Other destinations for which mail is accepted:             HOSTNAME.tardis.ed.ac.uk
Visible domain name for local users:                       tardis.ed.ac.uk
IP address or host name of the outgoing smarthost:         mailhost.tardis.ed.ac.uk
Keep number of DNS-queries minimal (Dial-on-Demand):       NO

NTP

Our router, davison, provides other machine with an NTP service. In turn, it synchronises with the (external-facing) Informatics servers. Here's how to update '/etc/ntp.conf':

--- /etc/ntp.conf       (revision 17)
+++ /etc/ntp.conf       (working copy)
@@ -10,17 +10,8 @@


 # You do need to talk to an NTP server or two (or three).
-#server ntp.your-provider.example
+server davison

-# pool.ntp.org maps to more than 300 low-stratum NTP servers.
-# Your server will pick a different set every time it starts up.
-#  *** Please consider joining the pool! ***
-#  *** <http://www.pool.ntp.org/join.html> ***
-server 0.debian.pool.ntp.org iburst
-server 1.debian.pool.ntp.org iburst
-server 2.debian.pool.ntp.org iburst
-server 3.debian.pool.ntp.org iburst
-
 # By default, exchange time with everybody, but don't allow configuration.
 # See /usr/share/doc/ntp-doc/html/accopt.html for details.
 restrict -4 default kod notrap nomodify nopeer noquery

Munin

Install munin-node on the client (the new Linux box) and update '/etc/munin/munin-node.conf' like so:

--- etc/munin/munin-node.conf   (revision 28)
+++ etc/munin/munin-node.conf   (working copy)
@@ -34,4 +34,4 @@
 # the allow line as many times as you'd like

 allow ^127\.0\.0\.1$
-
+allow ^193.62.81.11$

Then run '/etc/init.d/munin-node restart' to update the daemon. Connect to the web server and update '/etc/munin/munin.conf' like so:

--- munin.conf.pert     2007-06-22 17:47:27.593900598 +0100
+++ munin.conf  2007-06-22 17:48:26.781493093 +0100
@@ -101,9 +101,11 @@
 [mara.tardis.ed.ac.uk]
     address 193.62.81.15
     use_node_name yes

-
+[wotan.tardis.ed.ac.uk]
+    address 193.62.81.4
+    use_node_name yes

Server addresses

This page is out of date and needs rewriting.
The content is likely to be incomplete or incorrect.

This provides the addresses of various servers which a Tardis machine might need to use.

DNS

We have an internal caching nameserver, currently leela, 193.62.81.14. However, other machines should be able to cope if it's down for maintenence, so we also use one of the university's servers. (Currently 129.215.200.7, but we should check if that's what we're supposed to use.)

Thus most machines have a /etc/resolv.conf along the lines of:

search tardis.ed.ac.uk
nameserver 193.62.81.14
nameserver 129.215.200.7

Others

See also

Other stuff that should be documented here, but isn't

  • Configuring machines to pass mail on to the mail hub
  • Configuring ntp
  • Booting our suns from the LAN
  • Installing munin