RE: [WinPcap-users] What is PROMISCOUS mode?

[Sushma]

Title: Message

Promiscuous Mode   In a network, promiscuous mode allows a network device to intercept and read each network packet that arrives in its entirety. This mode of operation is sometimes given to a network sniffer that captures and saves all packets for analysis (for example, for monitoring network usage). In an Ethernet local area network (LAN), promiscuous mode is a mode of operation in which every data packet transmitted can be received and read by a network adapter. Promiscuous mode must be supported by each network adapter as well as by the input/output driver in the host operating system. Promiscuous mode is often used to monitor network activity. Promiscuous mode is the opposite of non-promiscuous mode. When a data packet is transmitted in non-promiscuous mode, all the LAN devices "listen to" the data to determine if the network address included in the data packet is theirs. If it isn't, the data packet is passed onto the next LAN device until the device with the correct network address is reached. That device then receives and reads the data. When you run tcpdump, it will put your NIC into what is known as "promiscuous" mode. Normally, when a NIC sees a packet being transmitted on the media, it only monitors the signal long enough to determine if that packet is destined for its MAC address. If it is addressed to its MAC address, it will load the entire packet into RAM until the TCP/IP protocol has a chance to process the packet. If it is not addressed to its MAC address, it will simply ignore the rest of the packet and wait to monitor the next packet that is transmitted. When a NIC is placed into promiscuous mode, it will load and process all packets, regardless of whom the packets are destined for. This doesn't mean that the original recipient won't receive its packet; instead, it means that the packet will be received by both the intended recipient and the NIC that is running in promiscuous mode. -----Original Message----- From: Daniel Frimerman [mailto:[EMAIL PROTECTED] Sent: Monday, June 30, 2003 10:57 AM To: [EMAIL PROTECTED] Subject: [WinPcap-users] What is PROMISCOUS mode? Can anyone please explain to me what does promiscous mode mean?   Daniel