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Network Configuration—BasicsMonitor ModePutting an interface in monitor mode means that the interface should not transmitanything over the physical interface. This is mostly the case on the passive sniffingport. You do not want anything to be transmitted and the host to be stealth onthe network.Enabling monitor mode on an interface prevents transmitting traffic on the interface.Consequently the interface cannot be used to transmit or forward traffic as long asthe monitor option is enabled.To enable monitor option on an interface, you may use ifconfig with themonitor flag:# ifconfig fxp0 monitorThis command puts the fxp0 interface into the monitor mode. To verify if an interfaceis in monitor mode, you should look for the monitor flag in the interface flags:# ifconfig xl0 | grep flagsxl0: flags=48843metric 0 mtu 1500Configuring Fast EtherChannelFast EtherChannel (FEC) allows grouping of multiple (up to eight) interfaces tocreate a high capacity virtual interface. Creating FEC interfaces can be done throughthe netgraph(4) subsystem, and you can easily create and maintain interfaces usingthe /etc/rc.conf configuration file.A sample configuration of a FEC interface, which is created by bonding two physicalinterfaces (bge0 and bge1), is shown in the configuration here:fec_interfaces="fec0"fecconfig_fec0="bge0 bge1"ifconfig_fec0="inet 192.168.21.4/24"The first line in the example tells the system to initialize a virtual interface calledfec0. You can specify multiple fec interfaces by separating the interface namesusing space. In the above example, FEC members are specified in the second line.You do not need to configure the IP address on the physical interface, and configurethe address on fec virtual interface instead.[ 118 ]