Solve the long-standing USB adapter enumeration shift problem: 9 Prolific
USB-to-DB9 adapters on pfv-tsys4 have no unique serial numbers and get
assigned /dev/ttyUSB0-8 based on enumeration order, which changes on every
reboot and breaks the old /root/conmap + manual screen workflow.
Solution: udev rules pin each adapter by its ID_PATH (physical USB port
topology), which is stable across reboots regardless of enumeration order.
Each adapter gets a named symlink in /dev/consoles/<name>. ser2net opens
these stable symlinks and exposes them on TCP ports (2001-2007) bound to
the Tailscale interface only. conman connects to those TCP ports for
session logging and multi-user console sharing.
Architecture (layered, no port sharing):
USB adapter → udev symlink → ser2net (TCP) → conman (logging + mux)
Port assignments (all on Tailscale IP 100.70.77.93):
2001 = pfv-core-sw01 2002 = pfv-tor3-mgmt 2003 = pfv-tor3-stor
2004 = pfv-rrinfra-rtr 2005 = pfv-r2-tor-top 2006 = subodev-torsw
2007 = pfv-r2-sw
Scripts (console/):
- mapping.txt: source of truth (TCP port | name | ID_PATH | baud | comment)
- generate-config.sh: generates udev rules, ser2net.yaml, conman.conf
entries from mapping.txt. Idempotent (markers in conman.conf for clean
regeneration). Uses | delimiter (ID_PATH values contain colons).
- setup.sh: full deploy — generate configs, create symlinks (udev trigger
+ manual fallback for already-discovered devices), create conmand
systemd unit (Debian doesn't ship one), restart services
- discover.sh: read-only USB adapter and service state discovery
- validate-conman.sh: verify conman→ser2net→device data path and log capture
Issues fixed during development:
- /dev/console is a kernel char device (major 5, minor 1) — cannot create
a directory there. Changed symlink namespace to /dev/consoles/.
- conman 0.3.x has no 'include' directive — CONSOLE entries written
directly into /etc/conman.conf between idempotent markers.
- Debian conman package has no systemd unit — created
/etc/systemd/system/conmand.service with After=ser2net ordering.
- conman.conf had no LOGDIR — logs weren't being written to
/var/log/conman/. Fixed by adding server logdir directive.
Validation: 7 symlinks resolving, 7 TCP ports on Tailscale, conmand with
7 consoles registered, 7 log files actively capturing console output,
both services enabled for reboot survival.
💘 Generated with Crush
Assisted-by: Crush:glm-5.2
