par tomtom » 13 Fév 2003 12:02
C'est tout à fait normal !
<BR>
<BR>Pour pouvoir pinger le lan distant depuis la passerelle il faut rajouter un secon tunnel.
<BR>
<BR>Si tu veux que les deux passerelles puissent se voir il t'en faut un troisième.
<BR>
<BR>Et enfin si tu veux que la passerelle distante joigne ton lan il faut un quatrième tunnel !
<BR>
<BR>L'expication tirée du site de freeswann (en anglais <IMG SRC="images/smiles/icon_razz.gif">)
<BR><!-- BBCode auto-link start --><a href="http://www.freeswan.org/freeswan_trees/freeswan-1.97/doc/adv_config.html" target="_blank">http://www.freeswan.org/freeswan_trees/freeswan-1.97/doc/adv_config.html</a><!-- BBCode auto-link end -->
<BR>
<BR>
<BR>
<BR><!-- BBCode Start --><B>
<BR>Multiple tunnels between the same two gateways </B><!-- BBCode End -->
<BR>Consider a pair of subnets, each with a security gateway, connected via the Internet:
<BR>
<BR> 192.168.100.0/24 left subnet
<BR> |
<BR> 192.168.100.1
<BR> North Gateway
<BR> 101.101.101.101 left
<BR> |
<BR> 101.101.101.1 left next hop
<BR> [Internet]
<BR> 202.202.202.1 right next hop
<BR> |
<BR> 202.202.202.202 right
<BR> South gateway
<BR> 192.168.200.1
<BR> |
<BR> 192.168.200.0/24 right subnetA
<BR>
<BR>tunnel specification such as:
<BR><!-- BBCode Start --><I>
<BR>conn northnet-southnet
<BR> left=101.101.101.101
<BR> leftnexthop=101.101.101.1
<BR> leftsubnet=192.168.100.0/24
<BR> leftfirewall=yes
<BR> right=202.202.202.202
<BR> rightnexthop=202.202.202.1
<BR> rightsubnet=192.168.200.0/24
<BR> rightfirewall=yes
<BR></I><!-- BBCode End -->
<BR>
<BR>will allow machines on the two subnets to talk to each other. You might test this by pinging from polarbear (192.168.100.7) to penguin (192.168.200.5).
<BR>However, this does not cover other traffic you might want to secure. To handle all the possibilities, you might also want these connection descriptions:
<BR>
<BR><!-- BBCode Start --><I>
<BR>conn northgate-southnet
<BR> left=101.101.101.101
<BR> leftnexthop=101.101.101.1
<BR> right=202.202.202.202
<BR> rightnexthop=202.202.202.1
<BR> rightsubnet=192.168.200.0/24
<BR> rightfirewall=yes
<BR>
<BR>conn northnet-southgate
<BR> left=101.101.101.101
<BR> leftnexthop=101.101.101.1
<BR> leftsubnet=192.168.100.0/24
<BR> leftfirewall=yes
<BR> right=202.202.202.202
<BR> rightnexthop=202.202.202.1
<BR>
<BR></I><!-- BBCode End -->
<BR>
<BR>Without these, neither gateway can do IPsec to the remote subnet. There is no IPsec tunnel or eroute set up for the traffic.
<BR>
<BR>In our example, with the non-routable 192.168.* addresses used, packets would simply be discarded. In a different configuration, with routable addresses for the remote subnet, they would be sent unencrypted since there would be no IPsec eroute and there would be a normal IP route.
<BR>
<BR>You might also want:
<BR>
<BR><!-- BBCode Start --><I>
<BR>conn northgate-southgate
<BR> left=101.101.101.101
<BR> leftnexthop=101.101.101.1
<BR> right=202.202.202.202
<BR> rightnexthop=202.202.202.1
<BR></I><!-- BBCode End -->
<BR>
<BR>This is required if you want the two gateways to speak IPsec to each other.
<BR>
<BR>This requires a lot of duplication of details. Judicious use of also= and include can reduce this problem.
<BR><BR><BR><font size=-2></font>
One hundred thousand lemmings can't be wrong...