Hi,
How much memory does NAT take? It seems with all the memory it must take, that it could also implement filtering at no extra memory charge???
I have packet filtering on on my outbound interface so that no requests from any of my private ip’s can enter the interface from inside or outside. All addresses from my private ip’s are translated into a public address pool.
I thought I could have the ip address of the outbound serial interface negotiated through the isp when the connection was made, but seems if I have an email server inside I need a permanent (non-negotiated) address.
There’s a serial connection on the outbound interface. Traffic comes through here from the inside headed for the internet (and I want replies to get in) (this is on one ethernet interface). Traffic also comes here from the outside to access an email server (this is on a second ethernet interface). These then must both be inside interfaces.
Do I need to specify public addresses for my remaining interfaces on this router??? I think not as I do not think that once NAT is done on ip’s entering the inside interfaces any address will be on the packet but the source address now translated by NAT.
Also I have a question regarding security. If I use NAT, NAT tables keep a record of every transaction. So what happens to packets where the ip and port are not in the NAT table? guess I still need packet filtering as a new NAT entry will be created for these and they will just go through unless I filter them?
How much memory does NAT take? It seems with all the memory it must take, that it could also implement filtering at no extra memory charge???
–cew
(Sorry I had some errors in this; I thought things through and edited it; I’m new studying for an exam; I really do not get that much practice; I took a course in 2004 but it was not for CISCO; I bought the books to study)
