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Alpine_5G/docs/DNS.md
nearxos 160ad641ce Add web GUI, docs, scripts, and 5G router config 
- Web app (Flask): status, config, firewall, logs, users, restart
- Docs: AT commands, deploy, DNS, quickstart, web GUI
- Scripts: connect, deploy, diag, healthcheck, modem-status, speedtest, status, troubleshoot
- Init and iptables: 5g-router, 5g-webgui, rules.v4
- CHANGELOG, TODO, REVISION; config and README updates
2026-02-02 09:38:23 +02:00

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DNS for Alpine 5G Router

The 5G modem gets DNS from the carrier (e.g. via AT+CGCONTRDP=1). The router and LAN clients need working DNS.

Option 1: Use carrier DNS (automatic)

When 5G is up, you can put the carrier DNS in /etc/resolv.conf so the router itself uses it. CYTA example:

nameserver 195.14.130.220
nameserver 195.14.154.100

To automate: in connect-5g.sh or a post-up script, if DNS_SERVERS is set in /etc/5g-router.conf, write it to /etc/resolv.conf after configuring the interface.

Example in config:

DNS_SERVERS="195.14.130.220,195.14.154.100"

A one-liner to apply (run after 5G is up):

echo "nameserver 195.14.130.220" > /etc/resolv.conf
echo "nameserver 195.14.154.100" >> /etc/resolv.conf

Option 2: dnsmasq (LAN DHCP + DNS)

dnsmasq can provide DHCP for LAN and act as DNS forwarder. Install and enable:

apk add dnsmasq
rc-update add dnsmasq default

Example /etc/dnsmasq.conf:

interface=eth0.100
dhcp-range=192.168.1.100,192.168.1.200,255.255.255.0,12h
dhcp-option=6,192.168.1.1

Then the router (192.168.1.1) must resolve DNS. Either:

  • Set /etc/resolv.conf on the router to carrier or public DNS (8.8.8.8, 1.1.1.1), or
  • Configure dnsmasq to use upstream servers: server=195.14.130.220 and server=195.14.154.100 (or 8.8.8.8).

So: router gets DNS from carrier or public; LAN clients get DHCP and DNS from dnsmasq (which forwards to those servers).

Option 3: Public DNS only

Ignore carrier DNS and use public resolvers on the router:

echo "nameserver 8.8.8.8" > /etc/resolv.conf
echo "nameserver 1.1.1.1" >> /etc/resolv.conf

Ensure ip_forward and NAT are set so LAN clients use the router and thus the same DNS path.

Summary

Role DNS source
Router /etc/resolv.conf (carrier or 8.8.8.8)
LAN clients dnsmasq (option 6 = router) or router as gateway + same resolv

After changing DNS, restart dnsmasq if used: service dnsmasq restart.