The lan_fw.zip file you have requested: Tools and Utilities / Misc / Lan Packet Forwarder - 25.77kb is not available. Perhaps try browsing all files for the game Half-Life and upload any files you want to share or are missing. This is the only information we could locate:
This file fools HL into thinking that clients from the Internet are on the server's LAN, enabling the server to run with +sv_lan 1 and accept 'net connections. This file is for ops who want to run an old school server.