Port Forwarding not working (still) OpenWrt 18.06

Installing and Using OpenWrt Network and Wireless Configuration
1

Hi all,

I'm trying to run a minecraft server on my home server (IP is 192.168.1.2 on the LAN). I've set up my OpenWRT 18.06 router as follows:

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If I use my mobile phone as a hotspot to try and connect from my desktop I get connection refused. If I use a port checker on the browser I'm told the port is closed. Windows firewall is off on the server, and I don't have any anti-virus installed (right now at least). Please help :slight_smile:

Thanks,Tom

2

I'm assuming this effectively makes your desktop "outside" your WAN, yes?

Did you intentionally map 40000 to 32400?

Web-based "port checkers" aren't always the most reliable in their results.

Do you need TCP and UDP both on those ports? I would only open what you need, once you establish that you can connect.

tcpdump (from tcpdump-mini) would let you watch what is coming into your WAN as well as what is going out to your server on 192.168.1.2. On the WAN, you could filter for ports 40000/32400, 25565, and 31244. On the LAN, you could filter for 192.168.1.2

3

Re: Plex, probably not, but Plex is working fine for the moment.

Yeah, phone hotspot means it's accessing the server as if anyone else on the internet might.

Entirely new to tcpdump, please could you point me to a guide on how to construct the arguments for that filter? I've installed tcpdump-mini and have ssh'd in to the router. Thanks.

4

Do you mean to put this part?

Screenshot%20from%202019-04-26%2014-11-25

Removing this source port may fix the issue.

1 Like
5

Yes, in almost all cases you should not specify source_port, it is too restrictive. A client chooses a random port as the source. If the client goes through a router with NAT the source port could be changed again.

6

Oops, OK, I've removed that, applied, and rebooted the router. Now I'm getting connection timeout when I attempt to connect. Any suggestions?

7

If your ports are correct, have you tired the firewall on the device 192.168.1.2?

8

The firewall on the server (192.168.1.2) is disabled.

EDIT:

I ran tcpdump on the port, here's the output, blanking out my IP of course :slight_smile: It doesn't look like it's doing any port forwarding unless I'm misreading it.

18:38:13.753730 IP (tos 0x0, ttl 126, id 19962, offset 0, flags [DF], proto TCP (6), length 52)
    My4gIP.62121 > MyDslIP.25565: Flags [S], cksum 0xea8f (correct), seq 4249516173, win 64240, options [mss 1452,nop,wscale 8,nop,nop,sackOK], length 0
18:38:19.741161 IP (tos 0x0, ttl 126, id 19963, offset 0, flags [DF], proto TCP (6), length 52)
    My4gIP.62121 > MyDslIP.25565: Flags [S], cksum 0xea8f (correct), seq 4249516173, win 64240, options [mss 1452,nop,wscale 8,nop,nop,sackOK], length 0

EDIT2: Oops, that's what happens when I use my phone as a hotspot while it's connected to the WIFI. Derp. If I use tcpdump -pnvvi ppoe-wan port 25565and try to connect nothing shows up in TCPDump. Any suggestions? Thanks

EDIT3: Note to self, rebooting router probably changes IP address when one does not have a static IP. Oops. Appears to be working now. Thanks :slight_smile: