ctf wargame beacon.asm Windows 32-bit Winsock API (static; no dependencies) 2,560 bytes

beacon.asm

; compile with MASM32
; C:\masm32\bin\ml /c /Zd /coff beacon.asm
; C:\masm32\bin\Link /SUBSYSTEM:WINDOWS beacon.obj
; beacon.exe
;
.386
.model flat, stdcall
option casemap :none
include C:\masm32\include\windows.inc
include C:\masm32\include\kernel32.inc
include C:\masm32\include\user32.inc
includelib C:\masm32\lib\kernel32.lib
includelib C:\masm32\lib\user32.lib
include C:\masm32\include\ws2_32.inc
includelib C:\masm32\lib\ws2_32.lib
.data
	uuid db "6220260a-0d5e-4290-89ac-c2d8d68c57a3", 0
	hSock dd ?
	_addr4 sockaddr_in <?>
	wsadata WSADATA <?>
.code
start:
	mov _addr4.sin_family, AF_INET
	mov _addr4.sin_port, 7017h ; 6000
	mov _addr4.sin_addr, 0100007fh ; 127.0.0.1
	invoke WSAStartup, 202h, addr wsadata
	invoke socket, PF_INET, SOCK_STREAM, IPPROTO_TCP
	mov hSock, eax
	invoke connect, hSock, addr _addr4, sizeof _addr4
	invoke send, hSock, addr uuid, sizeof uuid, 0
	; invoke closesocket, hSock
_loop:
	invoke Beep, 60, 2000
	invoke Sleep, 1000
	jmp _loop
	invoke ExitProcess, 0
end start 

API Monitor v2 is a good tool for debugging win api stuff
the WIN32.HLP is at https://www.modula2.org/win32tutor/references.php

script just needs a few tweaks to customize behavior. probably don't want it to beep in production, and probably want it to close socket and reconnect between loop intervals. can just rearrange and comment/uncomment lines above to achieve desired effect.

some of the include libs may be possibly omitted, may result in even smaller binary.