Messenger Service
From Wikipedia, the free encyclopedia
Messenger Service is a network-based system notification service included in some versions of Microsoft Windows. This service, although it has a similar name, is not related in any way to the .NET Messenger Service or the Windows Messenger and MSN Messenger instant messaging clients.
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[edit] Utilities
[edit] Net Send
The Net Send command allows users to use the Messenger Service under Windows XP Professional and Home editions. It only requires that the Messenger Service be started. The syntax of the command is:
net send {IP address/computer name} {message}
For example:
net send cls-mem67495 "This is a message."
The above example uses a computer name, not an IP address. Either way, the message will be sent as long as the target computer has the Messenger Service running.
This method of instant messaging requires no Internet connection; rather, just a local network. This is due to the architecture of the MailSlot protocol, which is what the Messenger Service is based on.
[edit] Winpopup
Winpopup sends messages from one Windows computer to another on the same LAN. It is available in all Windows versions from Windows 3.0 to Windows Me, but has never been included with Windows NT-based operating systems.
[edit] Abuse
The Messenger Service was originally designed for use by system administrators to notify Windows users about their networks[1]. It has been used maliciously to present pop-up advertisements to users over the Internet (by using mass-messaging systems which sent a desired message to a specified range of IP addresses). Even though Windows XP included a firewall by default, many users never enabled it and received such messages. For this reason it has been disabled by default at popular demand in the second Service Pack for Windows XP, a change perhaps redundant as the same service pack also enabled the firewall by default.
In order to use the Messenger Service functionality of Windows through the NET SEND command, either by itself or with the use of a third party NetBIOS messaging application, it is recommended that the NetBIOS ports cannot be reached from sources external to the local network. The ports that can be used by the Messenger service are 135, 137, 138, and 139. Many Internet service providers currently block access to these NetBIOS ports over the Internet, helping to prevent spamming even for older unfirewalled clients.
Microsoft provides instructions to disable this service to avoid messaging spam via this service.
The Messenger Service is no longer supported from Windows Vista and Windows Server "Longhorn".
[edit] Architecture
The Messenger Service, unlike many other network utilities included with Windows, uses the NetBIOS protocol. The service waits for a message, then it displays it onscreen. The alternative way to send message is to write it to a MailSlot named messngr.
