Rubin Shrestha
Rubin Shrestha
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Router IPV6 routing to IPV4 (?)

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What am I trying to do?

  • Make my services which are running on a Linux server, reachable over the internet;
  • My Linux server is connected to internet through two ‘consecutive’ routers;
  • The problem is that the router connecting me to the internet only offers the possibility to do port forwarding over IPV6.

Below you’ll find all the details of the hardware and network setup

Network Setup

Devices

Router 1 (R1)

  • R1 is connected to the ISP via fiber optics.
  • R1 is one of those “box” given by the ISP.
  • R1 has a DHCP service running and gives local addresses in IPV4 and IPV6 based on the MAC address of the chosen device.

R1 is NOT able to perform port forwarding with IPV4, it can ONLY do it with IPV6.

Locally the IP address of R1 is 192.168.1.1

Router 2 (R2)

  • R2 is an ‘old’ Netgear WNDR3700v5. But it does the job so far: Gigabit Ethernet, 300Mbps Wifi -> it’s WAY enough for what I need!
  • R2 is connected via its WAN port (ethernet cable) to R1 for the internet -> this works perfectly -> internet is reachable.
  • R2 gets TWO IP addresses from R1 (WAN): 192.168.1.42 and 2A02:842A:CCC0:A601:F2F8:CCB7:878B:4242/64 in IPV6. BOTH of those addresses are fixed manually in the DHCP service running on R1.
  • R2 on its own LAN operates on the network 192.168.42.0 / 255.255.255.0
  • R2 is able to act as a DHCP server for ipv4
  • R2 is NOT able to act as a DHCP server for ipv6 -> so R2 has an IPV6 on its WAN interface BUT R2 cannot be used as an IPV6 LAN router for its own LAN.

Router 3 (R3)

  • R3 is connected to R1 via Power-line communication (PLC)
  • R3 is a small wifi router that I can use as an alternative WiFi Network

Linux server (PC1)

Runs the services:

  • Openwebui/Ollama on port 3000
  • Emby on port 8096
  • Is connected via ethernet cable to R2

Windows desktop computer (PC2)

  • This computer runs Windows
  • It is connected to R2 via ethernet cable

Mobile Phone (PC3)

  • I use it only to test stuff
  • I can easily connect it to R2 or R3 depending on which WiFi I choose to connect to.

Network Map

  • PC1&PC2 <==LAN-IPV4-ONLY==> R2 <==LAN-IPV4 and IPV6==> R1 <==Fiber Optics==> internet
  • PC3 <====WiFi====> R3 <======== PLC ===========>R1

Network Address Map

  • R1.lan.ipv4: 192.168.1.1

  • R1.lan.ipv6: <I actually don’t know this one Oo>

  • R2.wan.ipv4: 192.168.1.42

  • R2.wan.ipv6: 2A02:842A:CCC0:A601:F2F8:CCB7:878B:4242/64

  • R2.lan.ipv4: 192.168.42.1

  • PC1.lan.ipv4: 192.168.42.2

  • PC2.lan.ipv4: 192.168.42.3

Port Forwarding

  • On R1, I have opened for both TCP and UDP the ports 3000 to 4000 for R2.wan.ipv6. This the KEY part right here -> I would LOVE to open those ports on R1 for R2.wan.ipv4 but it’s simply not possible, there’s literally NO user interface allowing me to do that 🙁

Software Setup

On PC1 is running the service Openwebui, on port 3000. This service is accessible from PC2.

What works

  • PC2 can access services on PC1 using PC1.lan.ipv4:3000

What doesn’t work

  • PC3 when connected to R3 cannot access anything on PC1.lan.ipv4:3000
  • And more importantly I haven’t managed to reach my service located at PC1.lan.ipv4:3000 from the “outside” (Internet)

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