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bclbob
join:2000-06-23
Oak Park, IL
·Verizon FiOS

bclbob

Member

NAT internal port with multiple external interfaces

I'm sorry to beg for help, but the documentation is confusing:

my router has 3 external internet interfaces and an internal interface.

I want to expose port 80 on the internal vlan to the outside, but want it to be available on all 3 external interfaces, all have different public IP addresses.

Any idea how to make that work?

RyanG1
Premium Member
join:2002-02-10
San Antonio, TX

RyanG1

Premium Member

Well considering that you will only have 1 default gateway packets will be sent out only 1 interface unless this is a bonded link. If thats the case then then opening ports for all 3 would be a moot point.

Im not aware of a clean way to make it work.
cramer
Premium Member
join:2007-04-10
Raleigh, NC
Westell 6100
Cisco PIX 501

cramer

Premium Member

said by RyanG1:

Im not aware of a clean way to make it work.

With something other than Cisco IOS / ASA... NAT isn't consulted until after routing, so the reply will not follow the same path. Sadly, this is something Linux (connection tracking) has gotten right for decades -- conntrack puts a forward/reverse reference in the route cache.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to bclbob

MVM

to bclbob
said by bclbob:

I want to expose port 80 on the internal vlan to the outside, but want it to be available on all 3 external interfaces, all have different public IP addresses.

Only way I can think of to make this work is 3 different public IPs nat'ing to 3 corresponding
different internal IP addresses on your internal server.

To some degree, I think this thread addresses some of this problem, ie. with a loadbalancer, or with DNS redirection.

My 00000010bits

Regards
bclbob
join:2000-06-23
Oak Park, IL

bclbob

Member

You all hit on my problem ok thanks, I thought I was going a bit crazy!