From owner-freebsd-net Thu Nov 29 5:36: 0 2001 Delivered-To: freebsd-net@freebsd.org Received: from khi.comsats.net.pk (khi.comsats.net.pk [210.56.4.10]) by hub.freebsd.org (Postfix) with ESMTP id 3171337B41B for ; Thu, 29 Nov 2001 05:35:54 -0800 (PST) Received: from company.mail (ppp7-190khi.comsats.net.pk [210.56.7.190] (may be forged)) by khi.comsats.net.pk (8.11.4/8.11.4) with ESMTP id fATDYI517417 for ; Thu, 29 Nov 2001 18:34:18 +0500 (PKT) Received: from ahsanalikh [192.168.0.1] by company.mail [192.168.0.1] with SMTP (MDaemon.PRO.v4.0.5.T) for ; Thu, 29 Nov 2001 18:34:26 +0500 Message-ID: <001301c178da$90108550$0100a8c0@ahsanalikh> From: "Ahsan Ali" To: References: <200111281637.fASGbgd07767@mail2.bigmailbox.com> <20011128170815.G3985@blossom.cjclark.org> <002d01c1788c$8388f4f0$be026b83@ahsanali> <20011128222900.L3985@blossom.cjclark.org> Subject: Re: netmask for aliased ip Date: Thu, 29 Nov 2001 18:01:04 +0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4807.1700 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 X-MDRemoteIP: 192.168.0.1 X-Return-Path: ahsan@khi.comsats.net.pk X-MDaemon-Deliver-To: freebsd-net@FreeBSD.ORG Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org > For TCP, that is what is always used by default when creating an > outbound connection. For incoming connections, the machine will of > course reply using the IP address the connection came in on. And a > program can always request to use a specific address if it wants to. > > I am not sure where you see a problem. What I am saying is that if you have (for instance) 192.168.0.0/24 as a network. Interface A has the IP 192.168.0.10 with a netmask of 255.255.255.0 (/24) Alias A:1 has the IP 192.168.0.11 with a netmask of 255.255.255.255 (/32) Now Host B (192.168.0.20 mask 255.255.255.0) tries to access Alias A:1 which is 192.168.0.11/32 so B sends to A:1 which it (correctly) assumes to be on its own network, Alias A:1 cannot however reach B without sending the data to its configured gateway. If routing is enabled on this host then it may be able to send the reply routed through Interface A only... My point is, that if the aliased interface also had a class c mask, this issue wouldn't have come up in the first place when considering local (within the same subnet) access from other hosts on that network. I know this sounds really obfusticating! :) But I'm just trying to get my concepts sorted out too. -Ahsan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message