Is there any way that I can get DHCP table?

[admin]

You should save the device IP in storage and periodically run the scan via a scheduled scripts to check for IP changes. You should also set a lower value for socket.http.TIMEOUT because default is 60 seconds to speed up the script. Check if your device has a non-standard TCP port open so the scan more consistent, because many network devices can have port 80 open.

Here's a script that can quickly check if any of local IPs have port 80 open:

Code:

require('socket')
prefix = '192.168.1.' -- ip address prefix
rangemin, rangemax = 2, 254 -- min/max of the scan range
port = 80 -- TCP port to check

sockets = {}
ips = {}

-- create sockets and connect
for i = rangemin, rangemax do
  ip = prefix .. i
  
  sock = socket.tcp()
  sock:settimeout(0)
  sock:connect(ip, port)

  sockets[ #sockets + 1 ] = sock
  ips[ sock ] = ip
end

-- get a list of sockets that can be written to, this means that the connection is established
_, res, err = socket.select(nil, sockets, 1)

res = res or {}

-- log IPs of all sockets that accepted the connection
for _, sock in ipairs(sockets) do
  if res[ sock ] then
    ip = ips[ sock ]
    log(ip)
  end

  sock:close()
end

-- clean-up in case running as a resident script
sockets = nil
ips = nil