I have a slight Problem with my NAT-Setup.
What I'm trying to do:
I have 2 VLANs (in this example 100 and 200) and want that they can access the Network via separate IPs. This should be accomplished by a
iptables NAT. I created this setup with pf (FreeBSD) but unfortunately the hardware I have to use is not compatible. I would love to that within our main router, but the CPU cannot handle such loads.
With IP-Tables etc. I'm just a noob ;)
User on VLAN 100 (10.100.0.0/24) -> 10.100.0.1 NAT xxx.yyy.zzz.6 -> Network
User on VLAN 200 (10.200.0.0/24) -> 10.200.0.1 NAT xxx.yyy.zzz.7 -> Network
All of this on the same physical Interface, with VLAN Interfaces etc.
This is my current config: /etc/network/interfaces
lo .... iface ens2f3 inet static address xxx.yyy.zzz.6 netmask 255.255.252.0 auto ens2f3.100 iface ens2f3.100 inet static address 10.100.0.1 netmask 255.255.255.0 vlan-raw-device ens2f3 iface ens2f3 inet static address xxx.yyy.zzz.7 netmask 255.255.252.0 auto ens2f3.200 iface ens2f3.200 inet static address 10.200.0.1 netmask 255.255.255.0 vlan-raw-device ens2f3
/etc/iptables/rules.v4 (automatically loaded)
#NAT TABLE *nat :PREROUTING ACCEPT [0:0] :INPUT ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :POSTROUTING ACCEPT [0:0] -A POSTROUTING -s 10.100.0.0/24 -o ens2f3 -j SNAT --to-source xxx.yyy.zzz.6 -A POSTROUTING -s 10.200.0.0/24 -o ens2f3 -j SNAT --to-source xxx.yyy.zzz.7 COMMIT # General Table *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] COMMIT # I know this setup is very insecure! I lockdown the server when I got NAT working
The Problem is that I can get with a 10.100.0.100 I can connect onto xxx.yyy.zzy.1 with exactly this IP (10.100.0.100; which shouldn't be possible) instead of the IP I should have obtained via NAT.
I've also tried marking the packages when they arrive at the interface and have seperate routing tables for them. There the problem above doesn't exist, but no connection to anywhere is possible
Could you please provide me tips on how to realize this with a Linux-based OS. If necessary I have another 10G Interface available