From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lopes Subject: Re: difference between DROPped pings and non existing hosts Date: Tue, 26 Apr 2005 20:48:38 +0200 Message-ID: <426E8D06.7050407@lopsch.com> References: <426E8530.6080203@lopsch.com> <876ef97a05042611161428df43@mail.gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <876ef97a05042611161428df43@mail.gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: netfilter-bounces@lists.netfilter.org Errors-To: netfilter-bounces@lists.netfilter.org Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: netfilter@lists.netfilter.org Tobias DiPasquale schrieb: > On 4/26/05, Daniel Lopes wrote: >=20 >>I would like to know how ICMP distinguishes between DROPped pings and >>non existing hosts. Both times you don=B4t get a reply from the >>destination host but if it doesn=B4t reply because it doesn=B4t exist y= ou >>get the correct destination unreachable message if it drops the request= s >>for example with IPTables you get a timeout. And I haven=B4t a clue why >>this is so. >=20 >=20 > In the case where you get a destination unreachable message back, its > the router that is responsible for the network on which the machine > you are trying to ping that is responding with that message. When ICMP > is dropped, the packet makes it to the host and thus the router does > not generate a destination unreachable message to send back to you. >=20 Hmm I forgot the hardware address. In the case the router can=B4t do a=20 address resolution he generates a ICMP error message because he won=B4t b= e=20 able to deliver the packet is that right? Thank=B4s so far for the reply :).