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On 2008-03-03, kashani <kashani-list@××××××××.net> wrote: |
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> Grant Edwards wrote: |
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> |
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>> I don't understand why I have to do NAT. Can you explain why? |
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>> (Or point me to docs that explain why?) |
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> |
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> router01.your.network.com |
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> eth0 - 10.11.12.1 |
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> eth1 - 24.1.2.231 - Comcast |
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> eth2 - 64.1.2.132 - Speakeasy |
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> |
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> Naturally RFC 1918 space is useless outside your network so |
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> you have to NAT. |
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Both of my gateways are on local networks and are doing NAT. |
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> However you need to make sure that you are making your policy |
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> routing decisions at eth0. You don't want traffic marked as |
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> originating from 24.1.2.231 going out eth2 |
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I don't have IP forwarding enabled, so that shouldn't happen. |
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> since Speakeasy could (and should) drop traffic that is not |
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> origination from its IP space. Additionally traffic will be |
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> routing back to your via Comcast connection resulting in |
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> asymmetric routing which can increase the chances of packets |
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> arriving out of order. |
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> |
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> router01.your.network.com |
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> eth0 - 24.2.3.1/29 |
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> eth0 - 64.2.3.1/29 |
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> eth1 - 24.1.2.231 - Comcast |
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> eth2 - 64.1.2.132 - Speakeasy |
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> |
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> Same case with this setup even with real IPs. The chances of convincing |
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> any ISP to accept routes smaller than /24 from you are tiny. And finding |
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> anyone who knows what you even want to do even when you have the IP |
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> space is pretty much non-existent. I know, I've tried. Same thing in |
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> this case, you'll NAT at eth1 and eth2 and policy router at eth0. |
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> |
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> If you are doing this from a single machine with two IP's and no other |
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> networks or interfaces, it should just work. |
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The machine will have different non-routing IPs on the two |
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interfaces where the two NAT/firewall/gateways are. The |
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machine does have interfaces/networks, but since I'm not |
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forwarding packets, they should be irrelevant. |
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> Linux should use the IP of interface the packet leaves from, |
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> but I'd use tcpdump to make sure. |
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Good idea. |
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-- |
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Grant Edwards grante Yow! Hello, GORRY-O!! |
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at I'm a GENIUS from HARVARD!! |
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visi.com |
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-- |
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