Groundwork for replacing the USG with the VyOS pair without anything on the
network noticing. Three pieces:
migration/unifi-export.py pulls 13 endpoints off the classic controller into
timestamped JSON plus a normalised inventory: 11 networks, 31 DHCP
reservations, 4 port forwards, 2 firewall rules, 0 static routes. Two things
this turned up that a naive export would have lost:
- 23 of the 31 reservations carry no network_id at all -- UniFi simply does
not store the binding -- so they are resolved by subnet containment
instead. Without that, three quarters of the reservations have no subnet
to be placed in.
- 30 of the 31 sit INSIDE the DHCP pool, which UniFi's dhcpd tolerates and
which is flagged as a warning rather than discovered at cutover.
migration/unifi-to-vyos.py turns that inventory into VyOS `set` commands for
DHCP and DNS only -- the services the USG owns that VyOS must reproduce. Not a
general converter. --prod and --sim come from one code path so the config
proven in the sim and the config applied to the firewalls cannot drift. Prod
mode hard-fails if any reservation is missing, since a silent drop is the
failure mode that matters.
DNS is included because the USG resolves for 5 of 6 VLANs today: UniFi hands
out the gateway's own address whenever dhcpd_dns is empty, verified by
labmaster resolving against 192.168.8.1. Replacing the USG without a forwarder
would take DNS away from those VLANs entirely.
labsim/labsim-dhcp-test.sh proves it by booting throwaway VMs with real
production MACs -- the one piece of production config that transplants
verbatim. Safe because ovs-labsim has no physical NIC, so those MACs cannot
reach the real LAN.
Result on VyOS 2026.08 (kea), 4/4: printer1 got 172.31.10.46 from inside the
pool, sonoff-matter got 172.31.11.67 across the /23 boundary, Hubitat got its
out-of-pool .2, and an unreserved MAC got an unreserved address. kea honours
in-pool host reservations -- the open question blocking the cutover.
Supporting changes to labsim:
- VLAN 10 widened to /23. Every reservation is in LoT and LoT spans 10.0.0.x
and 10.0.1.x, which a /24 cannot represent.
- LoT's host leg moved to .3, because 10.0.0.2 is a real reservation
(Hubitat) that maps onto the host's own address.
- vlans.conf gained optional masklen and host_octet fields, defaulting to
24 and 2 so the other five VLANs are untouched.
- Fixed /etc/network/interfaces hardcoding 255.255.255.0. That file is what
actually takes effect on these Alpine guests -- cloud-init's
network-config is ignored -- so any non-/24 VLAN was silently wrong.
Two generator bugs found by VyOS rejecting the output: static-mapping names
are validated as hostnames, so underscores fail; and two devices named
"espressif" plus two named "thebeast" collided into single names, which would
have overwritten one reservation with another's address.
The raw export holds WiFi passphrases and the WAN PPPoE credentials and is
gitignored.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
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