Send message with NetSend through LAN?

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Originally posted by Walter
Hostname or IP address, basically ;)

And the popup ad's you mentioned use net send... as long as port 139 (NetBios) is open and the Messenger service is running on the remote computer, you can send a message to it. Even to Win 9x/ME computer if WinPopup is open.

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Netbios utilises ports 137,138,139. Port 137/TCP is used for name resolution, 138/UDP is for connectionless data transfer and 139/TCP is for connection orientated data transfer.

By default these ports are protected by Windows to ensure only communication is within the local network. However, as of Windows 2000 net send makes use of the remote procedure call on port 135, which is not protected. By using port 135 the spammer is then told by the remote machine what port the messenger service is listening on. This is usually a high numbered un protected port.

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Originally posted by visualAd
Netbios utilises ports 137,138,139. Port 137/TCP is used for name resolution, 138/UDP is for connectionless data transfer and 139/TCP is for connection orientated data transfer.

By default these ports are protected by Windows to ensure only communication is within the local network. However, as of Windows 2000 net send makes use of the remote procedure call on port 135, which is not protected. By using port 135 the spammer is then told by the remote machine what port the messenger service is listening on. This is usually a high numbered un protected port.

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Well, I didn't know that! Although the ports aren't protected by Windows. That's what the Internet Connection Firewall of Windows XP does, but only if it's enabled on the correct interface. It's also why it's a good idea to have a proper firewall if you're connected to the Internet and have open shares on a network.

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Originally posted by Walter
Well, I didn't know that! Although the ports aren't protected by Windows. That's what the Internet Connection Firewall of Windows XP does, but only if it's enabled on the correct interface. It's also why it's a good idea to have a proper firewall if you're connected to the Internet and have open shares on a network.

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They arn't protected in the sense that they are blocked. However, Windows checks the NetBios name can be resolved to an IP address when it recieves a NetBios datagram and if it cannot then it is discarded. As NetBios is not a routable protocol, anything outside your local LAN will be ignored.

I wouldn't know anything about that, but it makes sense :D

Still a problem for computers connected directly to the Internet with file and print sharing enabled.

Anyways, I think we've pretty much covered most of what there is, and beaten it to death with a big stick. As our posts have nothing to do with the original question, I think we should stop posting in this thread now ;)