From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard van Breemen Date: Thu, 28 Feb 2002 13:24:55 +0000 Subject: Re: [LARTC] Newbie question Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org On Thu, Feb 28, 2002 at 01:31:36PM +0100, Arthur van Leeuwen wrote: > > Yep: by adding the rule: > > ip rule add from 172.16.1.0/24 table isp1 > > everything *WILL* go to table isp1. > Bzt. Every packet with a source address matching 172.16.1.0 will have > table isp1 searched first. If no route comes up for it the packet will still > be routed according to table main. Yes, but that table contains a default route. And since the gateway is accessible, it ends there... > > In my experience everything even local traffic that matches the rule > > will go to the isp1 table, and hence will be routed to the gateway. > Local traffic should not be routed over this host anyway. The only thing > that will break is traffic from this host to the local network. If you have a local ip in that network (172.16.1.0/24), and connect to that local ip... > > Use a normal routing table for isp1: > > For instance: > > ip route add 172.16.1.0/24 dev {right device} scope link > > to make sure that you can still route back to 172.16.1.0... > This is good advice. Very good advice. It makes for a much clearer > configuration. It is not only clear, but also necessary in this case. Because the next line is a default route... Ehhh, unless the machine is not link local to 172.16.1.0/24... > > Anyway: tcpdumping all of your interfaces will make you clear what is > > actually happenning. > Not always. Besides, the information you need is in the routing tables... > why not look at that instead and try to figure out what should happen? > > (Ofcourse, this will not show programs sneakily changing the TOS of a > connection... but still... the information can be found in the routing > tables, if you count the cache as a routing table as well... :)) Allright, if you are experencied, you only have to do ip route get.... But to become experienced you need to know what is going on. > > Thinking about it: it only contains a default route, which means, it > > only knows that it should route to that default gateway. > > The default is I guess some sort of end point in a routing table. > Any route is an endpoint. Once a route has been found, the routing algorithm > will quit searching, and just route out that route. This has interesting Unless the gateway is considered dead, and an alternate route exists... > consequences, as the first thing searched is always the cache... and you can > even manipulate *that* by hand. >:) Interesting side effects as in, "hey, it suddenly does not work anymore!". :) -- Telegraaf Elektronische Media http://wwwijzer.nl http://leerquoten.monster.org/ http://www.faqs.org/rfcs/rfc1855.html Let your government know you value your freedom. Sign the petition: http://petition.eurolinux.org/ _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/