<?xml version="1.0" encoding="utf-8"?><!DOCTYPE article  PUBLIC '-//OASIS//DTD DocBook XML V4.4//EN'  'http://www.docbook.org/xml/4.4/docbookx.dtd'><article><articleinfo><title>DenyHosts</title><revhistory><revision><revnumber>10</revnumber><date>2008-03-18 17:28:21</date><authorinitials>localhost</authorinitials><revremark>converted to 1.6 markup</revremark></revision><revision><revnumber>9</revnumber><date>2007-01-03 13:03:14</date><authorinitials>ac3bf1</authorinitials></revision><revision><revnumber>8</revnumber><date>2006-12-16 18:00:39</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>7</revnumber><date>2006-12-16 17:59:09</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>6</revnumber><date>2006-12-16 17:48:31</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>5</revnumber><date>2006-12-16 17:44:21</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>4</revnumber><date>2006-12-16 17:43:39</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>3</revnumber><date>2006-12-16 17:42:06</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>2</revnumber><date>2006-12-16 17:36:05</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision><revision><revnumber>1</revnumber><date>2006-12-16 17:33:01</date><authorinitials>ACD50C3C.ipt.aol.com</authorinitials></revision></revhistory></articleinfo><section><title>Prevenire attacchi brute-force con dizionario - DenyHosts</title><para>Tratto dall’articolo di: Falko Timme &lt;ft [at] falkotimme [dot] com&gt; </para><para> URL: <ulink url="http://www.howtoforge.com/preventing_ssh_dictionary_attacks_with_denyhosts"/> </para><para> Traduzione: ac3bf1</para><para>In questo <ulink url="http://ninux.org/DenyHosts/HowTo#">HowTo</ulink> si discuteranno i passaggi per installare DenyHosts su una macchina Linux. DenyHosts è un tool che osserva i login via SSH, e se trova dei login non andati a buon fine dallo stesso IP, DenyHosts blocca ogni successivo tentativo di accesso da quel indirizzo IP inserendolo in /etc/hosts.deny. In questo tutorial DenyHosts sarà installato ed eseguito come daemon.</para><section><title>1 Istallazione</title><para>Per compilare ci servira pithon2.3-dev su Debian. </para><screen><![CDATA[apt-get install python python2.3-dev python2.3
]]><![CDATA[
cd /tmp
wget http://mesh.dl.sourceforge.net/sourceforge/denyhosts/DenyHosts-2.0.tar.gz
tar –xzvf DenyHosts-2.0.tar.gz
cd DenyHosts-2.0
python setup.py install]]></screen><para>Questa procedura scaricherà DenyHosts in /tmp, e lo installerà in /usr/share/denyhosts </para></section><section><title>2 Configurazione</title><screen><![CDATA[cd /usr/share/denyhosts
cp denyhosts.cfg-dist denyhosts.cfg]]></screen><para>edita denyhosts.cfg (vi denyhosts.cfg) file di esempio <ulink url="http://ninux.org/DenyHosts/DenyHosts?action=AttachFile&amp;do=get&amp;target=denyhosts.cfg">denyhosts.cfg</ulink> </para><para>attenzione a SECURE_LOG e LOCK_FILE sono molto importanti </para><para>per Debian sono: </para><screen><![CDATA[SECURE_LOG = /var/log/auth.log
LOCK_FILE = /var/run/denyhosts.pid]]></screen><para>Variabili opzionali. Vi consiglio di configurare i log per email se li volete con queste variabili: </para><screen><![CDATA[ADMIN_EMAIL =
]]><![CDATA[
SMTP_HOST =
SMTP_PORT = 25
SMTP_FROM =
SMTP_SUBJECT = DenyHosts
#se necessari levare il # da davanti
#SMTP_USERNAME=
#SMTP_PASSWORD=]]></screen><para>Servirà anche daemon control quindi: </para><screen><![CDATA[cp daemon-control-dist daemon-control]]></screen><para>edita daemon-control (vi daemon-control) facendo attenzione a DENYHOSTS_BIN, DENYHOSTS_LOCK, and DENYHOSTS_CFG. Per Debian sono le seguenti: </para><screen><![CDATA[DENYHOSTS_BIN = "/usr/bin/denyhosts.py"
DENYHOSTS_LOCK = "/var/run/denyhosts.pid"
DENYHOSTS_CFG = "/usr/share/denyhosts/denyhosts.cfg"]]></screen><para>File di esempio <ulink url="http://ninux.org/DenyHosts/DenyHosts?action=AttachFile&amp;do=get&amp;target=daemon-control">daemon-control</ulink> </para><para>Ora bisogna rendere il file eseguibile: </para><screen><![CDATA[chown root daemon-control
chmod 700 daemon-control]]></screen><para>Per creare lo script di avvio: </para><screen><![CDATA[cd /etc/init.d
ln -s /usr/share/denyhosts/daemon-control denyhosts
update-rc.d denyhosts defaults]]></screen><para>e infine lo avvimao: </para><screen><![CDATA[/etc/init.d/denyhosts start]]></screen><para>Per attivare la variabile PURGE_DENY del file denyhosts.cfg  utilizzare la seguentestringa per l’avvio: </para><screen><![CDATA[/etc/init.d/denyhosts start --purge]]></screen><para>Vi consiglio di configurare I parametric per la posta in denyhosts.cfg per ricevere notifica di attacchi.</para><para> DenyHosts: <ulink url="http://denyhosts.sourceforge.net"/> </para></section></section></article>