Some information of Debian systems

This document describes some configuration customizations and other sysadmin tasks I do when I set up a Debian host.

Debian post-installation commands

dpkg-reconfigure locales

Reconfigure locales, for example to en_US en_US.UTF-8 fr_FR.UTF-8 fr_FR@euro. Keep in mind SSH preserve locale across the connection so a single UTF-8 locale is not enough.

dpkg-reconfigure console-data && dpkg-reconfigure keyboard-configuration

Change which keyboard configuration to use. loadkeys can also be used, with keymaps in /usr/share/kbd/keymaps. After this: service keyboard-setup restart.

cd /usr/bin && sudo ln -s python python2

For scripts which require python2 command.

update-rc.d $SERVICE remove or sysv-rc-conf

Remove some unneeded services from boot. Opposite operation is defaults.

Enable persistent iptables configuration:

apt-get install iptables-persistent
systemctl enable netfilter-persistent.service

Or persistent nftables configuration:

systemctl enable nftables.service

APT configuration

This configuration doesn’t install recommended packages by default.


APT::Install-Recommends "0";
APT::Install-Suggests "0";

To configure an HTTP proxy, you need to add one more line:

Acquire::http::Proxy "";

/etc/apt/sources.list file depends on your location:

# Here is this file for a Debian Unstable in the US.
deb     sid main contrib non-free
deb-src sid main contrib non-free

# And here for a Debian Squeeze server in Germany
deb          squeeze main contrib non-free
deb squeeze/updates main contrib non-free

You may install debsums package to check the integrity of the installed files. There is a cron job with debsums which is configured by /etc/default/debsums:

# Set this to never to disable the checksum verification or
# one of "daily", "weekly", "monthly" to enable it

Apticron is a program which automatically downloads the new updates (without installing them) and send mails about them. By default, it is configured to run every day. To change this to a weekly-based period, you need to edit /etc/cron.d/apticron:

# Sunday, 0:41
41 0 * * 0 root if test -x /usr/sbin/apticron; then /usr/sbin/apticron --cron; else true; fi

Apache commands

a2dismod status

Disable the status module.

a2dissite default

Disable the default site, you need to write your own site file and enable it.

Postfix configuration

To send system messages by email, it is a good idea to have a mail server on an host which is configured as an “Internet Site”. On a Debian host Postfix seems to be a good choice and is easy to install, configure and manage.

Reload aliases after any change in /etc/aliases:

postaliases /etc/aliases || newaliases
postfix reload

/etc/aliases example:

postmaster: root
abuse: root
user: root
www: web

The name of the mail system is written down in /etc/mailname.