Utility: LANegram - NET SEND Replacement [VB6]

[dilettante]

Well I can't take a lot of credit for quick responses, I just happen to be looking in here lately!

Crossing VLANs depends entirely on how they are connected by switching and routing. The issue is that we're using Mailslot broadcasts. As far as I recall for NetBT these use:

UDP 138, NETBIOS-DGM, NetBIOS datagram service

Unless such broadcasts are allowed to pass unhindered you can't use LANegeam between your VLANs. Network admins often have legitimate reasons for blocking these (poorly behaved applications may generate excessive chatter) and part of the reason for VLAN and similar technologies is to isolate such traffic anyway.

In "modern" AD domains the domain servers get around this by filtering traffic and passing things to each other via TCP connections. LANegram has no way to piggyback on this though, and would need to have its own "broadcast relay servers" on each VLAN, and of course they'd need to be configured to know about each other.

I can't recall how the old NET SEND and Messenger Service dealt with this in later Windows versions. Perhaps those messages just "fell on the floor" as well?