Get public IP address of TP-Link router, for dynamic DNS

tp-link-router-ip.rb

# Fetches the public IP of a TP-Link Archer MR400 router.
# For some reason, this wasn't the same as you see from a _device_ connected to
# the router, so typical FreeDNS updates which use the IP of the device
# requesting the update weren't working.

# You must install the 'snmp' gem and enable SNMP in the router settings.

require 'snmp'

# The local IP address of the router
GATEWAY_IP = "192.168.1.1"

# This is "ipAddrEntry", found with iReasoning
ip_addr_entry_oid = SNMP::ObjectId.new("1.3.6.1.2.1.4.20.1")

# Connect to the router over SNMP
manager = SNMP::Manager.new(host: GATEWAY_IP)

# Grab public IP object
ip_obj = manager.get_next(ip_addr_entry_oid).varbind_list[0]

# Get IP, as a dotted string
ip = ip_obj.value.to_s

# Print
puts ip

thanks for sharing -- this is exactly what i need :)