DMZ and no access to ports on public ip?

Installing and Using OpenWrt Network and Wireless Configuration
13

Your ISP's router isn't configured to allow "hairpin NAT".

14

Yes and i don't have any access the the config gui. The ISP configured a DMZ for me on 192.168.254.2. Because of that, i use a OpenWRT router too. (IP 192.168.1.1)

What's the "best" directory in put in my iptables workaround script. It needs to start like a service - without any user interaction, not manually, with every router boot:

#!/bin/sh
set -x && wget -qO- http://ipecho.net/plain > ./public_ip.txt
for IP in $(cat ./public_ip.txt); do iptables -t nat -A PREROUTING -d $IP -m tcp -p tcp --dport 80 -j DNAT --to-destination 192.168.1.171; done
iptables -t nat -A POSTROUTING -d 192.168.1.171 -s 192.168.1.0/24 -j SNAT --to-source 192.168.1.1 && rm -f ./public_ip.txt
15

That depends on the contents of the include directive in /etc/config/firewall.

By default it points to the file at /etc/firewall.user but that can be changed.

1 Like
16

It should be executed AFTER all other firewall rules...

17

Bung your custom rules in a separate script, then use a sleep timer to delay the execution of the script, on each startup:

sleep 60
/etc/myfirewallrules
18

Thank you very much, will look for that..:slight_smile:

1 Like
19

Isn't that the correct path to execute it automatically?

/etc/init.d/iptables_custrules.hm

instead of

/etc/iptables_custrules.sh

?

20

https://openwrt.org/docs/techref/preinit_mount may contain some relevant information.

21

Can you disable NAT on the OpenWrt router.

22

No. Because of that i think i need to change my ISP soon!!
Now are problems that the service seems to run too early:

23

Nat Loopback ist the problem. But i have a DMZ, configured by ISP

24

Since you've got control over DNS, either through DHCP or by configuring "your" clients, make it easy on yourself and set up a "local override" for www.example.com to 192.168.1.171

1 Like
25

i don't like domain to ip entries on client, e.g. the windows hosts file or something like that...

26

and i need to check the web service runs on public ip address!! there is no other way!!!

27

maybe my smartphone, tor browser or a vpn connection to bypass the nat loopback problem... no, not really...!!

28

You're making it far too complicated

  • DHCP points clients to "your" local DNS server
  • Clients on your network with static addresses you point to your local DNS server
  • That server gives out 192.168.1.171 as the A record for www.example.com

No need to know your public IP address for any internal hosts.

I do this with unbound on my network for my public-facing mail, web, and MQTT hosts. You should be able to do the same with dnsmasq as well.

29

i don't have an own local dns. my router do relay from public dns servers.

30

Much easier to set up dnsmasq or unbound than all you're trying to do.

Even if you get half of hairpin NAT working, how are you going to deal with the return packets if the two hosts are on the same network?

Outbound packet

192.168.1.100 => publicIP gets routed to 192.168.1.1 and NAT-ed to
192.168.1.100 => 192.168.1.171

Return packet

192.168.1.171 => 192.168.1.100 which is link-local and never touches the router

Your host never sees publicIP => 192.168.1.100

Edit -- Here's what I would do

Ignore the subnet that your ISP gives you, configure your OpenWrt WAN for 192.168.254.2 -- that's effectively a one-to-one mapping of your public IP.

Put all your hosts behind the OpenWrt box.

Set up dnsmasq on your OpenWrt box to provide DHCP and DNS

Set up dnsmasq on your OpenWrt box to resolve whatever hostname(s) you want to the IP of the service host on your behind-OpenWrt net.

Set up port forwarding on your OpenWrt box to forward 192.168.245.2:nnnn to the IP and appropriate port of the service host on your behind-OpenWrt net.

Done.

Want a little more security? Put your service hosts on their own subnet and route to them from your internal hosts. Firewall as appropriate between the two. (I personally wouldn't trust the security of "win10 machine with apache" exposed to the Internet.)

1 Like
31

That's what i have done, the port forward works. but the problem was the access to my external ip form my own subnet (where the server is)...

32

-> "NAT Loopback". And yes, i occurs too when i put my server directly into the 192.168.254.xx zone from the ISP's router. So the Nat loopback problem is there, and not on OpenWRT...

The Win10 Machine with Apache is just for testing. It's my own laptop and not a server