Greek - Masquerading Made Simple HOWTO

John Tapsell

      <tapselj0@cs.man.ac.uk>

Thomas Spellman

      <thomas@resonance.org>

Matthias Grimm

      <DeadBull@gmx.net>

ÌåôÜöñáóç óôá åëëçíéêÜ áðü: Sotiris Ganouris

      <topgan1@clug.gr>
   Éóôïñéêü ÁíáèåùñÞóåùí
   Áíáèåþñçóç 0.08 2002-07-11 ÅðéìÝëåéá áðüjpt
   Áíáèåþñçóç 0.07 2002-02-27 ÅðéìÝëåéá áðüjpt
   Áíáèåþñçóç 0.06 2001-09-08 ÅðéìÝëåéá áðüjpt
   Áíáèåþñçóç 0.05 2001-09-07 ÅðéìÝëåéá áðüjpt
   Áíáèåþñçóç 0.04 2001-09-01 ÅðéìÝëåéá áðüjpt
   Áíáèåþñçóç 0.03 2001-07-06 ÅðéìÝëåéá áðüjpt

   ¼ëïé  ïé  óõããñáöåßò  åßíáé äéáèÝóéìïé óôï êáíÜëé #debian óôïí
   irc.opensource.net

   Ï  John  Tapsell  (JohnFlux)  åßíáé  ï åðßóçìïò óõíôçñçôÞò ôïõ
   how-to.

   Óôåßëôå  ìïõ  Email  (John  Tapsell)  ãéá  ïðïéáäÞðïôå áðïñßá,
   âñéóéÜ, ó÷üëéá, ñáíôåâïý êôë.

   Ç  êëïðÞ  Ýãéíå  ìå  íôñïðÞ  áðï  ôç äïõëåéÜ ôïõ David Ranch -
   <dranch@trinnet.net>.

   Áõôü  ÄÅÍ  åßíáé  áíôéêáôÜóôáóç  ãéá ôïõ IP-Masquerading HOWTO
   åßíáé  Ýíá  óõìðëÞñùìá  óå  áõôü, êáé ôá äýï ôïõò èá ðñÝðåé íá
   äéáâáóôïýí  ìáæß.  Äåí  ãñÜöù ðñÜãìáôá åäþ ðïõ äåí êáëýðôïíôáé
   áðï  ôï  Üëëï  HOWTO,  ïýôå êáé åîçãþ ôé óçìáßíïõí üëá áõôÜ, Þ
   ãéáôß  ãßíïíôáé  üëá áõôÜ. Äåßôå åäþ http://ipmasq.cjb.net êáé
   ôï  ðñþôï Masq-HOWTO ïðïõ åßíáé áñêåôÜ êáëýôåñá guides ïðïõ èá
   óáò âïçèÞóïõí ðåñéóóüôåñï.

   Ôï  êåßìåíï  áõôü  ðåñéãñÜöåé  ôï  ðùò íá åíåñãïðïéÞóåôå ôï IP
   Masquerade  feature óå Ýíá óõãêåêñéìÝíï Linux host. Ôï IP Masq
   åßíáé  ìßá ìïñöÞ ôïõ Network Address Translation Þ åí óõíôïìßá
   NAT  ïðïõ  åðéôñÝðåé  åóùôåñéêÜ  óõíäåäåìÝíïõò  õðïëïãéóôÝò óå
   äßêôõï ðïõ äåí Ý÷ïõí ìßá Þ ðåñéóóüôåñåò êáôá÷ùñçìÝíåò Internet
   IP  äéåõèýíóåéò  íá áðïêôÞóïõí ôçí äõíáôüôçôá íá óõíäåèïýí óôï
   Internet ìÝóù ìßáò Internet IP (óýíäåóçò) åíüò Linux Box.

   Ïëï   ôï  êåßìåíï  âñßóêåôáé  êÜôù  áðï  ôçí  Üäåéá  GNU  Free
   Documentation License.

   http://www.gnu.org/copyleft/fdl.html
     _________________________________________________________

   Ðßíáêáò Ðåñéå÷ïìÝíùí
   1. ÅéóáãùãÞ
   2. Ðåñßëçøç: (Ìïõ áñÝóåé íá êÜíù ôéò ðåñéëÞøåéò ðñþôá)
   3. Ëßãï âáèýôåñç Ýêäïóç
   4. Post-install Ïäçãßåò
   5. FAQ's - Frequently Asked Compla Questions, Óõ÷íÜ ÐáñÜð
          ÅñùôÞóåéò

1. ÅéóáãùãÞ

   Ôá ðáñáêÜôù åßíáé åðßôçäåò ìéêñÜ áëëÜ ìÝóá óôï íüçìá.

   ÅÜí  Ý÷åôå  Ýíá  äßêôõï  ðïõ  èÝëåôå  íá ôï åíóùìáôþóåôå ìå ôï
   Internet:

   [network.png]
     _________________________________________________________

2. Ðåñßëçøç: (Ìïõ áñÝóåé íá êÜíù ôéò ðåñéëÞøåéò ðñþôá)

   ÕðïèÝôùíôáò  ïôé  ç  êÜñôá  äéêôýïõ ðïõ äßíåé åîùôåñéêü äßêôõï
   (ÉÍÔÅÑÍÅÔ)  åßíáé  ç  eth0,  êáé  ç  åîùôåñéêÞ  ìáò IP åßíáé ç
   123.12.23.43  êáé ç åóùôåñéêÞ êÜñôá äéêôýïõ (åóùôåñéêü äßêôõï)
   åßíáé ç eth1, ôüôå Ý÷ïõìå:
$> modprobe ipt_MASQUERADE # ÅÜí áõôü áðïôý÷åé óõíå÷ßóôå Ýôóé êáé áëëéþ
ò
$> iptables -F; iptables -t nat -F; iptables -t mangle -F
$> iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 123.12.23.43
$> echo 1 > /proc/sys/net/ipv4/ip_forward

   Ç ãéá ìßá óýíäåóç dial-up:
$> modprobe ipt_MASQUERADE # ÅÜí áõôü áðïôý÷åé óõíå÷ßóôå Ýôóé êáé áëëéþ
ò
$> iptables -F; iptables -t nat -F; iptables -t mangle -F
$> iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
$> echo 1 > /proc/sys/net/ipv4/ip_forward

   ÌåôÜ ãéá íá ôçí ðñïöõëÜîïõìå:
$> iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$> iptables -A INPUT -m state --state NEW -i ! eth0 -j ACCEPT
$> iptables -P INPUT DROP   # ìüíï åÜí ôá äýï ðñþôá åßíáé åðéôõ÷çìÝíá
$> iptables -A FORWARD -i eth0 -o eth0 -j REJECT

   ¹  ãéá  ìßá  óýíäåóç  dial-up (ìå ôçí eth0 óáí åóùôåñéêÞ êÜñôá
   äéêôýïõ):
$> iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$> iptables -A INPUT -m state --state NEW -i ! ppp0 -j ACCEPT
$> iptables -P INPUT DROP   #only if the first two are succesful
$> iptables -A FORWARD -i ppp0 -o ppp0 -j REJECT

   Êáé  áõôü  Þôáí! Ãéá íá äåßôå ôïõò êáíüíåò ôùí iptables ãñÜøôå
   "iptables -t nat -L"
     _________________________________________________________

3. Ëßãï âáèýôåñç Ýêäïóç

   ÊÜíùíôáò compile ôïí ðõñÞíá: (×ñçóéìïðïéÞóôå Ýíáí 2.4.x ðõñÞíá
   Þ ìåãáëýôåñï)

   ×ñåéÜæåóôå ôéò ðáñáêÜôù ñõèìßóåéò óôïí ðõñÞíá:

     * ÊÜôù áðï ôï Networking Options
          + Network packet filtering (CONFIG_NETFILTER)
     * ÊÜôù áðï ôï Networking Options->Netfilter Configuration
          + Connection tracking (CONFIG_IP_NF_CONNTRACK)
          + FTP Protocol support (CONFIG_IP_NF_FTP)
          + IP tables support (CONFIG_IP_NF_IPTABLES)
          + Connection state match support
            (CONFIG_IP_NF_MATCH_STATE)
          + Packet filtering (CONFIG_IP_NF_FILTER)
               o REJECT target support
                 (CONFIG_IP_NF_TARGET_REJECT)
          + Full NAT (CONFIG_IP_NF_NAT)
               o MASQUERADE target support
                 (CONFIG_IP_NF_TARGET_MASQUERADE)
               o REDIRECT target support
                 (CONFIG_IP_NF_TARGET_REDIRECT)
          + Packet mangling (CONFIG_IP_NF_MANGLE)
          + LOG target support (CONFIG_IP_NF_TARGET_LOG)

   Ðñþôá,  åÜí  ôá  iptables  êáé  ôï masq module äåí Ý÷ïõí ãßíåé
   compile óôïí ðõñÞíá êáé äåí åßíáé åãêáôåóôçìÝíá, áëëÜ õðÜñ÷ïõí
   óáí modules, ÷ñåéáæüìáóôå íá ôá åãêáôáóôÞóïõìå. Åáí êÜíåôå Ýíá
   insmod  ipt_MASQUERADE  èá öïñôþóåé ôá ip_tables, ip_conntrack
   êáé ôï iptable_nat.
$> modprobe ipt_MASQERADE

   ÁíåîáñôÞôùò  Üí  ôï  Intranet  (åóùôåñéêü  äßêôõï)  óáò  åßíáé
   ìåãÜëï,  Þ  áðëþò èÝëåôå äýï ôñåéò õðïëïãéóôÝò íá óõíäåèïýí ìå
   ôï Internet äåí õðÜñ÷åé ìåãÜëç äéáöïñÜ.

   ÕðïèÝôùíôáò ïôé äåí õðÜñ÷ïõí Üëëïé êáíüíåò óôá iptables, êÜíôå
   Ýíá:
$> iptables -F; iptables -t nat -F; iptables -t mangle -F

   ÅÜí  ðáßñíåôå Ýíá ëÜèïò ïðïõ ëÝåé ïôé äåí âñßóêåé ôá iptables,
   ðçãáßíôå êáôåâÜóôå ôá êáé åãêáôáóôÞóôå ôá. ÅÜí óáò ðåé ïôé äåí
   õðÜñ÷åé  ï  ðßíáêáò  'nat',  êÜíôå recompile ôïí ðõñÞíá ìå nat
   support.  Åáí  óáò  ðåé  ïôé äåí õðÜñ÷åé ðßíáêáò 'mangle', ìçí
   óôåíá÷ùñéÝóôå,  äåí  ÷ñåéÜæåôå  ãéá ôï ìáóêÜñéóìá. ÅÜí óáò ðåé
   ïôé  ôá  iptables  åßíáé  áóýìâáôá ìå ôïí ðõñÞíá óáò, ðçãáßíôå
   êáôåâÜóôå Ýíáí ðõñÞíá 2.4.x Þ ìåãáëýôåñï êáé êÜíôå ôïõ compile
   ìå iptables support.

   Áí  Ý÷åôå ÓÔÁÈÅÑÇ (static) ip êÜíôå (ð.÷. Óå êÜñôá äéêôýïõ ðïõ
   äåí ÷ñçóéìïðïéåß DHCP):
$> iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 123.12.23.43

   Ç  ãéá  äõíáìéêÞ  (dynamic)  (ð.÷.  ¸íá modem ðïõ ÷ñåéÜæåôå íá
   êáëÝóåôå Ýíáí áñéèìï ðñþôá (dialup):
$> iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

   ÔåëéêÜ  ðñÝåðé  íá  ðåéôå  óôïí  ðõñÞíá  ðùò  íáé,  èÝëåôå  íá
   îåêéíÞóåé  ôï  forwarding  (ç  ðñïþèçóç)  ôùí  ðáêÝôùí:  (Áõôü
   ÷ñåéÜæåôå  íá  ãßíåé  ìüíï  ìéá  öïñÜ  óå êÜèå reboot áëëÜ äåí
   ðåéñÜæåé íá ôï êÜíåôå êáé ðáñáðÜíù öïñÝò)
$> echo 1 > /proc/sys/net/ipv4/ip_forward

   Ïôáí  èá  Ý÷åôå  óéãïõñåõôåß ïôé üëá áõôÜ äïõëåýïõí (äåßôå ôéò
   ïäçãßåò  Post-install  ðñþôá) áöÞóôå íá äïõëåýåé ôï ìáóêÜñéóìá
   ìüíï  ôïõ  åóùôåñéêïý  äéêôýïõ  äåí  èÝëåôå íá áöÞóåôå üëï ôïí
   êüóìï óôï Internet íá ôï ÷ñçóéìïðïéïýí öõóéêÜ :)

   Ðñþôá,  áöÞóôå  ôéò  Þäç  õðÜñ÷ïõóåò  óõíäÝóåéò,  Þ  ïôéäÞðïôå
   ó÷åôßæåôå  ìå  áõôÝò  (ð.÷. Ôçí óýíäåóç óå Ýíáí server ftp ðïõ
   Ý÷åôå óõíäåèåß åóåßò)
$> iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

   ÅÜí áõôü óáò âãÜëåé ìýíçìá ëÜèïõò, ôüôå ôï ðéï ðéèáíü åßíáé íá
   ìçí  Ý÷åôå  åíåñãïðïéÞóåé  ôï state tracking óôïí ðõñÞíá êÜíôå
   recompile.  ÌåôÜ  áöÞóôå  êáéíïýñéåò  óõíäÝóåéò  ìüíï  áðï  ôï
   intranet  (ôïðéêü/åóùôåñéêü äßêôõï). ÁíôéêáôáóôÞóôå ôï ppp0 ìå
   eth0  Þ  ìå  ïôéäÞðïôå  åßíáé  ç  åîùôåñéêÞ óáò óõóêåõÞ. (Ôï !
   óçìáßíåé ïôéäÞðïôå åêôüò áðï)
$> iptables -A INPUT -m state --state NEW -i ! ppp0 -j ACCEPT

   Êáé ôþñá áñíçèåßôå ïôéäÞðïôå Üëëï:
$> iptables -P INPUT DROP   #only if the first two are succesful

   ÅÜí  ïðïéïóäÞðïôå  áðï ôïõò äýï ðñþôïõò êáíüíåò áðïôý÷åé, ôüôå
   áõôüò  ï  ôåëåõôáßïò  êáíüíáò  èá  åìðïäßóåé  ôï ìáóêÜñéóìá íá
   äïõëÝøåé  åíôåëþò. Ãéá íá áíáéñÝóåôå áõôüí ôïí êáíüíá ìðïñåßôå
   íá ãñÜøåôå "iptables -P INPUT ACCEPT".
     _________________________________________________________

4. Post-install Ïäçãßåò

   Ïëá èá ðñÝðåé íá ëåéôïõñãïýí ôþñá. Ìçí îå÷Üóåôå íá:

     * Ñõèìßóôå  üëïõò  ôïõò  õðïëïãéóôÝò  ôïõ  õðïäéêôýïõ óáò íá
       äåß÷íïõí  óôçí  ÉP  ôïõ  Linux  server  óáí  gateway. (Óôá
       windows äåîß-êëéê óôï network
       neighbourhood->properties->gateway  êáé  ìåôÜ ôïí áëëÜæåôå
       óôçí IP ôïõ Linux server(gateway)).
     * Ñõèìßóôå  üëïõò  ôïõò õðïëïãéóôÝò óáò íá ÷ñçóéìïðïéïýí ôïí
       proxy  ôïõ ISP óáò (áí õðÜñ÷åé ÷ñçóéìïðïéåßóôå transparent
       proxy),   (ÐÑÏÓÏ×Ç   Å÷ù   áêïýóåé  ãéá  áíáöïñÝò  ïôé  ôï
       transparent  proxying  åéíáé  ðïëý  áñãü  óå  ðïëý  ìåãÜëá
       äßêôõá),  Þ  ôñÝîôå ôïí squid óôïí linux server óáò. (Áõôü
       åßíáé ðñïáéñåôéêü áëëÜ óõíéóôÜôáé ãéá ìåãÜëá äßêôõá).
     * ÓéãïõñåõôÞôå ïôé âÜæåôå óùóôÜ ôïí DNS üôáí ñõèìßæåôáé ôïõò
       õðïëïãéóôÝò  óáò.  ÅéäÜëùò  èá ðáßñíåôå ìõíÞìáôá ëÜèïõò óå
       áõôïýò  ãéáôß  äåí  èá  ãßíåôå  óùóôÜ  ôï resolving ôçò IP
       address.
       [Offtopic]  I  wonder  if you could simply send out a dhcp
       broadcast  that  just  forwards  on  the  dns  server (and
       http_proxy  while  you're at it) without having to setup a
       dhcp server (or even if you do). Can someone mail me about
       this? :)
       Thanks to Richard Atcheson for pointing this out.
     * Ôþñá  èá  ðñÝðåé  óéãÜ óéãÜ íá äéïñèþíåôáé ôçí áóöÜëåéá óå
       áõôüí.   Ðñþôá   áðåíåñãïðïéÞóôå  ãåíéêþò  ôï  forwarding:
       "iptables  -P  FORWARD DROP", êáé ìåôÜ ìÜèåôå íá äïõëåýåôå
       ìå   ôá   iptables  êáé  ôá  áñ÷åßá  /etc/hosts.allow  êáé
       /etc/hosts.deny  ãéá íá áóöáëßóåôå ôï óýóôçìÜ óáò. ÐÑÏÓÏ×Ç
       Ìçí  äïêéìÜóåôå  ôï ðñïçãïýìåíç êáíü ôùí iptables ìÝ÷ñé íá
       Ý÷åôå  ôï  ìáóêÜñéóìá íá äïõëåýåé óùóôÜ ÐñÝðåé íá ïñßæåôáé
       îå÷ùñéóôÜ  ïðïéïäÞðïôå  ðáêÝôï  èÝëåôå  íá  ðåñÜóåé åÜí èá
       ÷ñçóéìïðïéÞóåôå  ôçí ðñïçãïýìåíç åíôïëÞ (êáíüíáò iptables)
       ìå  DENY.  (Ìðïñåßôå  íá  áíáéñÝóåôå  áõôüí  ôïí êáíüíá ìå
       "iptables -P FORWARD ACCEPT")
     * ÁöÞóôå üðïéá services èÝëåôå íá öáßíïíôáé óôï internet.
       Ãéá  ðáñÜäåéãìá  ãéá íá áöÞóåôå access óôïí web server óáò
       êÜíôå:
$> iptables -A INPUT --protocol tcp --dport 80 -j ACCEPT
$> iptables -A INPUT --protocol tcp --dport 443 -j ACCEPT
       Ãéá íá áöÞóåôå ôï ident (ãéá óýíäåóç óôï irc êôë) êÜíôå
$> iptables -A INPUT --protocol tcp --dport 113 -j ACCEPT

   Ãéá íá ôï äïêéìÜóåôå:

     * ÄïêéìÜóôå íá óõíäåèåßôå áðï Ýíáí õðïëïãéóôÞ ðåëÜôç óôï web
       ÷ñçóéìïðïéþíôáò   ìéá   IP.   Ç   IP   ôïõ   Google  åßíáé
       216.239.33.100  (ìßá  áðï üëåò ðïõ Ý÷ïõí) êáé èá ðñÝðåé íá
       ðáñåôå  ìßá  áðÜíôçóç áðü áõôÞí ð.÷. "ping 216.239.33.100"
       "lynx 216.239.33.100".
     * ÄïêéìÜóôå ìéá óýíäåóç ìáæß ìå ôï resolve ôïõ hostname ð.÷.
       "ping www.google.com" "lynx google.com" Þ áðï ôïí Internet
       Explorer Þ ôïí netscape

   Ïðïõ   eth0   åßíáé   ç   êÜñôá  äéêôýïõ  ðïõ  äßíåé  Internet
   (åîùôåñéêÞ), êáé ç 123.12.23.43 åßíáé ç åîùôåñéêÞ ip áõôïý ôïõ
   ìç÷áíÞìáôïò.
     _________________________________________________________

5. FAQ's - Frequently Asked Compla Questions, Óõ÷íÜ ÐáñÜð ÅñùôÞóåéò

     * Ðùò âëÝðù ôïõ êáíüíåò ùò ôþñá?
       - ÄïêéìÜóôå
$> iptables -L
$> iptables -t nat -L
     * Äåí  êÜíåé  resolve  ôéò IP! ÃñÜöù 'www.microsoft.com' êáé
       ëÝåé ïôé äåí ôï âñßóêåé
       -  ÓéãïõñåõôÞôå ïôé Ý÷åôå âÜëåé ôéò ñõèìßóåéò dns óå üëïõò
       ôïõò õðïëïãéóôÝò-ðåëÜôåò.
     * Äåí  äïõëåýåé!  Äåí ôïõ áñÝóïõí ôá iptables / NAT / SNAT /
       MASQ
       -  ÊáôåâÜóôå  ôïí  ôåëåõôáßï  ðõñÞíá, êÜíôå Ýíá compile ìå
       õðïóôÞñéîç iptables êáé NAT
     * Äåí  äïõëåýåé!  Ôï  ìáóêÜñéóìá (masquerading) äåí äïõëåýåé
       êáèüëïõ! Áåé ðíßîïõ âëÜêá
       - ÄïêéìÜóôå echo 1 > /proc/sys/net/ipv4/ip_forward
     * Äåí äïõëåýåé! Äåí ìðïñþ íá ÷ñçóéìïðïéÞóù ôï äßêôõï êáèüëïõ
       ðëÝïí êáé óå ìéóþ!
       - ÄïêéìÜóôå
$> iptables -F
$> iptables -t nat -F
$> iptables -t mangle -F
       (üëïé  ïé êáíüíåò Ýöõãáí Üíôå ãåéá). ÌåôÜ åðáíáöÝñåôå ôïõò
       ðñïçãïýìåíïõò êáíüíåò ðïõ ôõ÷üí åß÷áôå.
       - ÄïêéìÜóôå iptables -P FORWARD ACCEPT
     * Áêüìá äåí äïõëåýåé
       -  H×ìì,  ôï "dmesg | tail" óáò âãÜæåé êÜðïéï ëÜèïò? ÊÜíôå
       êáé Ýíá "cat /var/log/messages | tail" ? Ï÷é ïôé íïéÜæïìáé
       êáé ðïëõ :)
     * Äåí êáôáëáâáßíù, ÄÅÍ ÄÏÕËÅÕÅÉ!
       - Äåí ìðïñþ íá îÝñù.. áëëÜ èá ðñÝðåé íá åßóôå óå èÝóç íá:
        1) ÐéíãêÜñåôå ôï åîùôåñéêü äßêôõï áðï ôï Linux box
        2) ÐéíãêÜñåôå áðï ôï Linux Box ôï åóùôåñéêü äßêôõï
        3) Áðï ôï åóùôåñéêü äßêôõï íá ðéíãêÜñåôå ôï Linux box
       Êáé áõôÜ ðñéí áñ÷ßóïõí ïé êáíüíåò ãéá ôï ìáóêÜñéóìá.
     * Where do I put this stuff?
       -  In the /etc/network/interfaces file, or firewall.rc. If
       you put it in the interfaces file, then put it as a pre-up
       to  the  external interface, and have "iptables -t nat -F"
       as the post-down.
     * Ðùò  ìðïñþ íá ôï êÜíù íá áíïßãåé ôçí óýíäåóç ìüíï üôáí ôçí
       ÷ñåéÜæïìáé?(ppp up on demand)
       -  ÕðïèÝôùíôáò  ïôé  ï  gateway ôïõ ISP óáò åßíáé áò ðïýìå
       23.43.12.43 , ôüôå ðñïóèÝóôå ìßá ãñáììÞ óáí ôçí ðáñáêÜôù:
       :23.43.12.43
       óôï ôÝëïò ôïõ áñ÷åßïõ /etc/ppp/peers/provider. (áõôü åßíáé
       ãéá    dynamic    IP    -    ãéá   static   IP   èá   Þôáí
       my.external.ip.number:23.43.12.43 )
       ÌåôÜ óôï ôÝëïò áõôïý ôïõ áñ÷åßïõ âÜëôå ìéá íÝá ãñáììÞ:
       demand
     * Ç óýíäåóç ðÝöôåé óõíå÷þò!
       -  Ðñþôá,  Ý÷åôå åíåñãïðïéÞóåé ôï dialing on demand? ÊÜíåé
       ôçí äïõëåéÜ ôïõ óùóôÜ? ÔóåêÜñåôå ôï
       /etc/ppp/peers/provider,  êáé  óéãïõñåõôÞôå  ïôé ç óýíäåóç
       dial up äïõëåýåé êáíïíéêÜ ðñéí äïêéìÜóåôå ôï ìáóêÜñéóìá.
       -  Äåýôåñïí,  áí  êÜôé ðçãáßíåé ôüóï ðåñßåñãá äïêéìÜóôå íá
       ãõñßóåôå  óå ðñïçãïýìåíï ðõñÞíá (Linux 2.4.3) êáé äåßôå áí
       åêåé ëåéôïõñãåß Äåí îÝñù ãéáôß...
     * Äåí  ìðïñþ  íá  ôá  êÜíù  üëá  áõôÜ  ìüíïò  ìïõ! ÈÝëù êÜôé
       åôïéìáôæßäéêï ìå GUI.
       - Óßãïõñá http://shorewall.sourceforge.net/
       Ãéá äåßôå ôï...
     * Ôá Cable modems Ý÷ïõí static Þ dynamic IP?
       - ÊáëÞ åñþôçóç.. ôï ðéï ðéèáíü åßíáé íá åßíáé dynamic.
     * Ïé êÜñôåò äéêôýïõ ðïõ óõíäÝïíôáé óå DHCP?
       - Åßíáé dynamic.
     * Ðùò äéá÷åéñßæïìáé ôá åóùôåñéêÜ services?
       -  Äïêßìáóôå íá êÜíåôå forwarding Þ redirecting ôéò ðüñôåò
       ôùí IP îáíÜ óéãïõñåõôÞôå ïôé ôá Ý÷åôå áóöáëßóåé óùóôÜ
     * Áðï  ôïõò  õðïëïãéóôÝò  ôïõ  åóùôåñéêïý  äéêôýïõ  ìðïñþ íá
       ðéíãêÜñù  ôçí  ip  ôïõ  linux  gateway,  áëëÜ äåí ìðïñþ íá
       óõíäåèþ óôï internet.
       -Ïêåç,  äïêéìÜóôå  "rmmod  iptable_filter"  - more info on
       this as I get it.
       - ÓéãïõñåõôÞôå ïôé äåí ôñÝ÷åôå ôï routed Þ ôï gated ãéá íá
       ôóåêÜñåôå ãñÜøôå "ps aux | grep -e routed -e gated".
       - ÊïéôÜîôå óôï http://ipmasq.cjb.net
     * Ðùò  ìðïñþ  íá  äþ  ðïéåò óõíäÝóåéò åßíáé óå éó÷ý áõôÞ ôçí
       óôéãìÞ (established)? ÊÜôé óáí ôï netstat..
       - ÄïêéìÜóôå cat /proc/net/ip_conntrack
     * ×ñåéÜæïìáé  ðåñéóóüôåñåò  ðëçñïöïñßåò  ãéá ôï squid ãéá ôï
       routing êôë!
       -   Äïêßìáóôå  íá  äéáâÜóåôå  ôï  Advanced  Routing  HOWTO
       http://www.linuxdoc.org/HOWTO/Adv-Routing-HOWTO.html
     * Áõôü ôï howto åßíáé ÷Üëéá! Ðùò èá ðáñáðïíåèþ óôá ðáëçêáñéá
       ðïõ ôï Ýãñáøáí?
       -  Ðçãáßíôå  óôï #debian óôï irc.opensource.net êáé âñåßôå
       ôïí   JohnFlux.   -   Óôåßëôå   ìïõ  Mail  (JohnFlux)  óôï
       tapselj0@cs.man.ac.uk
     * Áõôü ôï howto åßíáé ÷Üëéá! Èá äïýìå êáìéá êáëõôåñç Ýêäïóç
       - ÄïêéìÜóôå http://ipmasq.cjb.net
       - Áðåõèõíèåßôå óôï LDP Masq-HOWTO.
     * Ìå ôé Üëëï áó÷ïëÞóå ôþñá?
       ÁõôÞí   ôçí   óôéãìÞ   ãñÜöù  Ýíáí  ïäçãü  óôï  linux  ãéá
       anti-missile-missiles-made-simple.   Äåí   õðÜñ÷ïõí  êáëïß
       ïäçãïß ðïõ íá óå ðñïóôáôåýïõí áðï ðõñçíéêÝò åêñÞîåéò. :)