dhcpd.leases dashboard

I was looking for a simple way to monitor the dhcpd(8) leases, subnet utilization and generally the state of the OpenBSD dhcpd server but I couldn't find any tool suitable for my needs. Most options are an overkill for the small APU routers that I need it for. So I made this:
A simple dashboard for the dhcpd.leases file of the OpenBSD dhcpd server that is very easy to deploy and use.
Basically all this dashboard does is present the data in dhcpd.leases plus some data from dhcpd.conf (currently only subnets and ranges) in a user friendly way including full dynamic searching, filtering and sorting. It can easily handle a few class C subnets or more, depending on your HW.

• Pure sh script. Runs on a base OpenBSD installation with no dependancies.
• Javascript and styles can be merged into the script to create a single file server or cgi script that is easy to deploy. This is the preferred way of using this script.
• Can optionally do MAC address Vendor lookup using the standards-oui.ieee.org data. Please note that Vendor lookup adds a lot to the processing time.
• Filtering, sorting and searching in the browser.
• Requires read access to /var/db/dhcpd.leases and /etc/dhcpd.conf files.

Safari on macOS

Firefox on OpenBSD

Iridium (Chromium) on OpenBSD

Installation

$ git clone https://github.com/facelessfish/dhcpd-leasesd (or Code/Download zip
and unzip)
$ cd dhcpd-leasesd
$ chmod +x dhcpd-leasesd
$ ./dhcpd-leasesd -dv -l <ip address to listen>

On first run (or after a reboot or after /tmp is cleared by the system) it will download the OUI data and cache it in /tmp if -v is specified. Wait for the download to finish and then visit: http://<ip address>:9130 with a fairly recent browser.
Tested on Safari, Firefox and Chromium.

To generate, install and start the single file server:

$ ./dhcpd-leasesd -f dhcpd-leasesd.sh
$ mv dhcpd-leasesd.sh /usr/local/sbin/
$ dhcpd-leasesd.sh -dv -l <ip address to listen> -p <port>

The dashboard can be served in 2 (+1) ways.

• Using the builtin nc(1) "HTTP server".
  This the easiest way to run the dashboard. Please note that it has a serious limitation of only 1 concurrent request (server is unavailable during processing).
  ex.

  $ dhcpd-leasesd -dv -l 192.168.0.1
  

• Using tcpserver(1).
  This option requires the ucspi-tcp package which contains the tcpsrver. Most flexible option due to the tcpserver configuration options. Can easily handle any number of concurrent requests.
  ex.

  $ tcpserver 192.168.0.1 9130 dhcpd-leasesd.sh -tv
  

• As a slowcgi(8) script for httpd(8).
  It should be possible to run it as a cgi but i havent tested it as it looks like more trouble than its worth.
  At the very least the following commands must be copied to /bin in the /var/www/ chroot:
  cat, date, grep, mkdir, mkfifo, nc, printf, rm, sh, tr, wc
  and then you'll have to copy ( and periodically update ) dhcpd.leases and dhcpd.conf to somewhere in the chroot.

Usage

dhcpd-leasesd [-b dhcpd.leases] [-c dhcpd.conf] [-t] [-v] [-u] [-f out_file] 
              [-d [-l listening_ip_address] [-p port]] 

Run without options will output HTML on stdout and exit.

-d Run as a deamon using the nc http server. Can only serve one request at a 
   time. -t is ignored (always on).

-l Listening address. Used only with -d. Default: 127.0.0.1

-p Listening port. Used only with -d. Default: 9130

-v Enable MAC address vendor lookup. Oui db will be downloaded and cached into
   /tmp if not already cached.

-t Prepend an HTTP 200 header to the HTML output. Needed when used with 
   tcpserver.

-b Path to dhcps.leases. Default: /var/db/dhcpd.leases

-c Path to dhcpd.conf. Default: /etc/dhcpd.conf

-u Update the vendor database and exit. All other options are ignored.

-f Merge the sh script, javascript and styles into out_file and exit. All other
   options are ignored.

Examples:
  $ dhcpd-leasesd.sh -d

  $ dhcpd-leasesd.sh -dv -b ./dhcpd.leases -c ./dhcpd.conf -l 0.0.0.0 -p 9130

  $ dhcpd-leasesd -f out.sh 

  $ tcpserver 192.168.0.1 9130 dhcpd-leasesd.sh -tv