srv-updater

README

dynv6 SRV Updater

This program sends signed UDP packets to dynv6 to keep the port of SRV records up to date. It only works with ed25519 keys.

Installation

go get github.com/dynv6/srv-updater

If you don't have a ed25519 key, generate one:

openssh-keygen -t ed25519

Usage

The SRV updater uses raw sockets. Therefore It needs root privilege or CAP_NET_RAW capability.

Command line arguments

  -dst-host string
    	the destination host (default "dynv6.com")
  -dst-port int
    	the destination port (default 55)
  -fqdn string
    	the hostname of the record you want to update (default "_service._tcp.example.com")
  -interval duration
    	sending interval (default 1m)
  -key string
    	private key (default "~/.ssh/id_ed25519")
  -priority uint
    	the priority of the record you want to update (default 10)
  -src-ip string
    	the local ip address (default should be determined)
  -src-port int
    	the local port (default 10000)
  -weight uint
    	the weight of the record you want to update (default 1)

Debugging

If the server does not understand the packet, it responds with a UDP packet containing an error message. You can read it with network protocol analyzers like tcpdump or wireshark.