Remember it's port 18444, and only works with nodes that are running regtest themselves. I think regtest has a higher minimum version requirement, e.g. always SegWit?
What exactly do you mean with " always SegWit"?
I manged it to run a regtest network with 3 nodes. With my program I connect to one of the nodes via tcp. The problem is that when I send the version message there is no reply (should be version and verack). My version messages content is the same as in the protocol documentation. (
https://en.bitcoin.it/wiki/Protocol_documentation#version) plus the header. My specific question was if there is a difference in the fields e.g. user_agent from the real network to the regtest. I already changed the magic value field (in the header). The content of the fields I sent are the following (before packing them):
Headermagic_number: 0xfabfb5da
command: "\x00" * (12 - len('version')))
length: len(payload)
checksum: e.g b'\x13+\x07\xf2'
payload: version payload from below
Version payloadversion: 70015
services: 0
timestamp: number like 1596794043
addr_recv: 127.0.0.1:18444
addr_from: 0.0.0.0:0
nonce: number like 615169444417225228
user_agent: b'\x0F/Satoshi:0.7.2/'
start_height: 478000
relay: 0
And the one regtest node I want to speak to is running on 127.0.0.1:18444
