Diff: DestinationNetworkUnreachable

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Newer page: version 4 Last edited on Thursday, April 12, 2007 3:04:58 pm by BenStaz
Older page: version 3 Last edited on Tuesday, June 1, 2004 11:38:26 pm by PerryLorier Revert
@@ -1,9 +1,11 @@
 [ICMP] reason subcode 0, used with ICMP reason code 3 to explain why a DestinationUnreachable message was sent. 
+If a router cannot forward a packet because it has no routes at all (including no default route) to the destination specified in the packet, then the router must generate a Network Unreachable.  
 It is usally generated by a gateway when it does not have a route for the destination specified in the IP packet that caused the error. 
 Note a server with a default gateway won't ever issue this message (since it always has a route for packets...). 
 Reject routes can also solicit this error. I recommend you add the routes below to any machine that is physically on the internet. It'll make any packet that doesn't have a more specific route (via some VPN, or locally connected machine) generate an [ICMP] DestinationNetworkUnreachable message and not just leak random IP's out onto the Internet. 
  route add -net reject metric 10000 
  route add -net reject metric 10000