# gpg --keyserver wwwkeys.eu.pgp.net --recv-keys XXXXXXXXXXXXXXXX
...
# apt-key add /root/.gnupg/pubring.gpg
...
# apt-get update
Where XXXX = the missing key
/etc/mysql/my.cnf
/etc/init.d/proftpd
/etc/warnquota.conf
/etc/logrotate.d/apache2
/etc/apache2/sites-available/default
/etc/apache2/ports.conf
/etc/apache2/apache2.conf
/etc/php5/apache2/php.ini
# PHPmyadmin things don't need to be changed.
/etc/phpmyadmin/config.header.inc.php
/etc/phpmyadmin/apache.conf
/etc/phpmyadmin/config.footer.inc.php
/etc/phpmyadmin/config.inc.php
/etc/services
/etc/samba/smb.conf
/etc/snmp/snmpd.conf
/etc/default/snmpd
/etc/snort/snort.conf
/etc/apache2/sites-available/default
/etc/acidlab/acid_conf.php
snort
/etc/bind/named.conf
apt-get install iotop