On 7/3/07 1:55 AM, "Martin Schiøtz" <malinux@xxxxxxxxx> wrote: > On 7/3/07, Grant Taylor <gtaylor@xxxxxxxxxxxxxxxxx> wrote: >> On 7/3/2007 1:52 AM, Martin Schiøtz wrote: >>> I'm going to setup a bridged NAT linux box for many users. I want one >>> outside IP address to serve for instance 10.0.0.0/22. >> >> Why do this with bridging? If you have a 10.0.0.0/22 network like you >> say, it is private and thus not globally routable. So, to reach the >> internet you will have to NAT to a globally routable IP. Thus you have >> a private subnet and a public subnet which is an ideal environment for a >> layer 3 router. Even if you are not going to a public IP but rather >> another private IP, the same scenario holds true. >> >> Or are you for some wanting wanting to perform a layer 3 function on >> layer 2? If so, can I ask why? > > Ok, I think your right here. > >> >>> I want to be sure that each local IP address always has 1024 NAT >>> sessions available and that sessions is kept even if the timeout is >>> reached. If 1024 sessions is reached and a new session is being >>> established then it will take over the oldest (timed out) session. >> >> I'm not sure that you will be able to specify how many NAT sessions each >> system will have and / or how to control the expiration there of. I do >> know that you will have (or did have to in previous kernels) to have a >> fair amount of RAM for the connection tracking table to not wrap on a >> network of that size. >> >>> Is this possible with iptables? >> >> The first part of what you want to do (layer 2 or layer 3) NATing, yes. >> >> As far as controlling how many sessions are reserved / maintained even >> beyond timeouts, I don't know. I'm betting not, especially to the latter. >> > > I guess the question was more about controlling the number of NAT > sessions pr. lokal IP address? If you give iptables a range, it will try to do as little port mangeling as possible, so I beilieve it will try to hold onto connections as long as possible. We saw quite a performance when we moved our 100 users from one Natted address to 64. I guess the mangeling made that much of a difference. Robert LeBlanc BioAg Computer Support Brigham Young University leblanc@xxxxxxx (801)422-1882
