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novusopiate
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Port Forwarding, firewall and self hosted game server help!

Mon Nov 29, 2021 9:16 pm

Hello all! **Warning, noob here so Beginner Basics seemed like the right place......**

I have a new RB2011 routerboard that I am wanting to use as a residential network device. I have the unit up and running easily and am pretty happy with the unit thus far.

HOWEVER!!!! I run a very small game server (Dungeons & Dragons on the FoundryVTT platform hosting on a headless linux box). This server was recently running without any problems on localip:30000 with a port forward set up to resolve a https domain to my public ip and then into my server.

I set up NAT forwarding rules on the RB2011(forwarding set for port 80, 443, and 30000 as the server relays jitsi video) and after a bit of research tried to amend the correct firewall rules to allow my server be publicly accessible. So far all I can muster is a "connection refused". Open port check tools cannot see my service on 30000 but I can access my server locally on localip:30000 as well as ssh into the linux box locally.

I am not as up to date on networking as I used to be and wanted to take a whirl at the mikrotik boards as they seemed like a really neat resource but I am finding it difficult to decipher some of the firewall rules in particular. Below are the NAT rules and some additional info I have seen requested elsewhere.

Thank you in advance for any help and patience! Next D&D session is Thursday! Oh hell!

Nat rules:
/ip firewall nat
add chain=dstnat action=dst-nat dst-address=*publicip* to-addresses=192.168.88.254 to-ports=30000 protocol=tcp dst-port=80
/ip firewall nat
add chain=dstnat action=dst-nat dst-address=*publicip* to-addresses=192.168.88.254 to-ports=443 protocol=tcp dst-port=443

More details:
/ip address print detail:
 0   ;;; defconf
     address=192.168.88.1/24 network=192.168.88.0 interface=ether2 actual-interface=bridge 

 1 D address=*publicip*/18 network=76.187.128.0 interface=ether1 actual-interface=ether1 
/ip route print detail:
 0 ADS  dst-address=0.0.0.0/0 gateway=76.187.128.1 gateway-status=76.187.128.1 reachable via  ether1 distance=1 scope=30 target-scope=10 vrf-interface=ether1 

 1 ADC  dst-address=76.187.128.0/18 pref-src=*publicip* gateway=ether1 gateway-status=ether1 reachable distance=0 scope=10 

 2 ADC  dst-address=192.168.88.0/24 pref-src=192.168.88.1 gateway=bridge gateway-status=bridge reachable distance=0 scope=10 
 
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pukkita
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Re: Port Forwarding, firewall and self hosted game server help!  [SOLVED]

Wed Dec 01, 2021 2:26 pm

1.- I assume you're using default firewall config from ROS, which opens automatically forwarded ports, check this rule actually exists:
/ip firewall filter
[...]
add action=drop chain=forward comment="defconf:  drop all from WAN not DSTNATed" connection-nat-state=!dstnat \
    connection-state=new in-interface-list=WAN 

This is required, otherwise firewall won't let the incoming connection pass.

2.- If D&D internal server listens on tcp/30000, this is wrong:
/ip firewall nat
add chain=dstnat action=dst-nat dst-address=*publicip* to-addresses=192.168.88.254 to-ports=30000 protocol=tcp dst-port=80 
You're forwarding external port 30000 to internal port 80... should be 30000 == 30000.

Additionally, you can make your life easier if not having a fixed public IP by referring to the in-interface or in-interface-list parameter instead of using the public IP.

i.e.:
/ip firewall nat
add chain=dstnat action=dst-nat in-interface-list=WAN to-addresses=192.168.88.254 to-ports=30000 protocol=tcp dst-port=30000
add chain=dstnat action=dst-nat in-interface-list=WAN to-addresses=192.168.88.254 to-ports=443 protocol=tcp dst-port=443
add chain=dstnat action=dst-nat in-interface-list=WAN to-addresses=192.168.88.254 to-ports=80 protocol=tcp dst-port=80

3.- Be sure to disable IP > Services > www and www-ssl.
 
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novusopiate
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Re: Port Forwarding, firewall and self hosted game server help!

Wed Dec 01, 2021 5:12 pm

Thank you for the notes! With your help and the help of Steveocee's hairpin NAT video, I have been able to clean up the initial mess I made!

The server is accessible from outside the local network via domain and running like a champ! However, internally I am unable to access the domain or public ip. Currently reading previous posts on split DNS and other possible solutions. I can load up my server on local network using internal ip, however it will not allow SSL which I need for the Jitsi video. So close! This whole process has been fascinating and I'm looking forward to learning more as I go.
 
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sunakashi
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Re: Port Forwarding, firewall and self hosted game server help!

Tue Feb 21, 2023 10:54 pm

3.- Be sure to disable IP > Services > www and www-ssl.
Please, can you explain why this option? Thanks.
 
Sob
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Re: Port Forwarding, firewall and self hosted game server help!

Tue Feb 21, 2023 11:01 pm

It's not needed, even if service on router uses some port and dstnat rule is for same one, dstnat sends packets elsewhere before they can reach service on router.

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