Re: Forcing all DNS traffic from the LAN to the firewall

[Rainer Kemme <news@panamail.de>]

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Hello,

Am 09.11.2020 um 18:47 schrieb Matthias Fischer:
> 
> "...I am trying to redirect all of my DNS traffic to go thru the
> IPFire DNS instead of directly to an outside DNS server...".
Before I replaced the old ZyXEL ZyWALL 35 by IPFire I intercepted / 
Redirected UDP 53 (DNS) and UDP 123 (NTP) using the ZyWALLs so called 
policy routing:

Based on the policy I redirected UDP 53,123 to one of my Linux machines.

On the Linux maschine I defined IPTABLE rules in order to redirect the 
requests to my favorite (internal) DNS-Server.

A rule for the request:
   iptables -t nat
            -A PREROUTING
            -p udp
            -s 172.22.100.0/22
          ! -d 172.22.0.0/16
           --dport 53
            -j DNAT
          --to 172.22.10.181

A rule for the reply:
   iptables -t nat
            -A POSTROUTING
            -p udp
            -s 172.22.100.0/22
            -d 172.22.10.181
           --dport 53
            -j SNAT
           --to 172.22.10.179

My LAN:
   172.22.0.0/16
The requesting range:
   172.22.100.0/22
The Linux machine
   172.22.10.179
My DNS-Server
   172.22.10.181

So, what I would appreciate in IPFire is a policy based routing :-)

Regards,
   Rainer