mapping the external WAN address to a Nginx variable

aag

5/1/23, 9:05 AM

I have an Nginx webserver within a LAN which is being addressed from the internet by NAT. The variable $server_addrcontains the internal LAN address of the server. Is there a way to map the external (internet-exposed) IP address of the webserver to an Nginx variable?

123

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nginx

Tero Kilkanen

5/1/23, 9:52 AM

What is the actual problem you are trying to solve?

aag

5/1/23, 1:07 PM

The WAN domain has a dynamic IP. It rarely changes, but it does change. I would like Nginx to serve dynamically depending on whether the client is accessing the server from the LAN (in which case the client's remote address will be the external WAN address).

djdomi

5/1/23, 4:33 PM

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aag

5/1/23, 6:06 PM

Dynamic DNS is a reality in many businesses as well. But it is easier for a camel to pass through the eye of a needle than to ask a question that will not elicit some patronizing comments by the self-appointed conoscendi.

Score:1

Server

Tero Kilkanen

5/1/23, 1:16 PM

nginx binds to all interfaces by default, it does not care about the interface IP addresses. So, it serves to any IP address, whether request comes via WAN or LAN.

You need to set up a dynamic DNS for your domain. Your server would contain a daemon that updates the new external IP to the dynamic DNS provider. Then all clients would use the dynamic DNS name to connect to the server.

Another alternative is to set up a DNS server in LAN, which would resolve the server's domain name to the LAN IP address, and then make LAN clients use that DNS server.

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Score:1

Server

aag

5/2/23, 1:11 PM

I have solved the issue with a cronjob to update a mapping file for the external IP address:

#!/usr/bin/env bash
# enumerate authorized networks
cat > /etc/nginx/current_ip.conf <<EOF
geo \$mysite_geo {
 default        "no";
 127.0.0.1      "yes";  # network which should have access
 10.10.0.0/16   "yes";  # network which should have access
 EOF

((echo "   " && (dig +short example.com | grep '^[.0-9]*$')) \
 && echo "\"yes\"; }  # current dynamic ip") |xargs -d'\n' \
 >> /etc/nginx/current_ip.conf

0 + 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: mapping the external WAN address to a Nginx variable

TH: การแมปที่อยู่ WAN ภายนอกกับตัวแปร Nginx

RO: maparea adresei WAN externe la o variabilă Nginx

RU: сопоставление внешнего адреса WAN с переменной Nginx

VI: ánh xạ địa chỉ WAN bên ngoài thành biến Nginx

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