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72 lines
2.0 KiB
Markdown
72 lines
2.0 KiB
Markdown
# DNS for Alpine 5G Router
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The 5G modem gets DNS from the carrier (e.g. via `AT+CGCONTRDP=1`). The router and LAN clients need working DNS.
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## Option 1: Use carrier DNS (automatic)
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When 5G is up, you can put the carrier DNS in `/etc/resolv.conf` so the router itself uses it. CYTA example:
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```
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nameserver 195.14.130.220
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nameserver 195.14.154.100
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```
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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.
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Example in config:
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```
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DNS_SERVERS="195.14.130.220,195.14.154.100"
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```
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A one-liner to apply (run after 5G is up):
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```sh
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echo "nameserver 195.14.130.220" > /etc/resolv.conf
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echo "nameserver 195.14.154.100" >> /etc/resolv.conf
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```
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## Option 2: dnsmasq (LAN DHCP + DNS)
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dnsmasq can provide DHCP for LAN and act as DNS forwarder. Install and enable:
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```bash
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apk add dnsmasq
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rc-update add dnsmasq default
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```
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Example `/etc/dnsmasq.conf`:
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```
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interface=eth0.100
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dhcp-range=192.168.1.100,192.168.1.200,255.255.255.0,12h
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dhcp-option=6,192.168.1.1
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```
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Then the router (192.168.1.1) must resolve DNS. Either:
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- Set `/etc/resolv.conf` on the router to carrier or public DNS (8.8.8.8, 1.1.1.1), or
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- Configure dnsmasq to use upstream servers: `server=195.14.130.220` and `server=195.14.154.100` (or 8.8.8.8).
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So: **router** gets DNS from carrier or public; **LAN clients** get DHCP and DNS from dnsmasq (which forwards to those servers).
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## Option 3: Public DNS only
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Ignore carrier DNS and use public resolvers on the router:
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```bash
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echo "nameserver 8.8.8.8" > /etc/resolv.conf
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echo "nameserver 1.1.1.1" >> /etc/resolv.conf
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```
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Ensure `ip_forward` and NAT are set so LAN clients use the router and thus the same DNS path.
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## Summary
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| Role | DNS source |
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|------------|--------------------------------------|
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| Router | `/etc/resolv.conf` (carrier or 8.8.8.8) |
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| LAN clients| dnsmasq (option 6 = router) or router as gateway + same resolv |
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After changing DNS, restart dnsmasq if used: `service dnsmasq restart`.
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