![]() ![]() I advise you to take a look at the RFC 1700, as there is a complete list of all protocols that IP encapsulates. IP encapsulates up to 100 different protocols. It shows how to grab protocols encapsulated by IP (Internet Protocol: network layer protocol), specifically, TCP and ICMP. This article demonstrates how an application can configure a socket connection to pay attention to all network packets, instead of only those addressed to it. Promiscuous mode puts a selected network interface to listening to all packets passing through it. Basically, what a sniffer really does is pay attention to all traffic by putting a network interface in the promiscuous mode state. What is a sniffer? A sniffer is an application that catches all network traffic from or to computers attached to a network. ![]() Beside the reference documentation, there are a few forum posts providing some info on how to use them, but not much more at the time of writing.Many people have used a sniffer at some time. The PowerShell cmdlets ( Add-VMSwitchExtensionPortFeature, Get-VMSystemSwitchExtensionPortFeature, etc) that can be used to manage port monitoring at the host level are not exactly user friendly and don’t cover all the relevant uses cases when it comes to internal ports. Some of the most typical use cases include network intrusion detection systems (NIDS), monitoring tools (Wireshark, Message Analyzer, tcpdump, etc) or software defined networking (SDN) routers / switches, like for example Open vSwitch. There are quite a few scenarios where you want to be able to receive on a VM all the traffic coming from an external network. Get- VMNetworkAdapter MyVM | ? MacAddress - eq 'xxxxxxxx' | Set- VMNetworkAdapter MyVM - PortMirroring Destination The Hyper-V PowerShell module does a great job in making life easy from this perspective, for example: In short, unlike other virtualization solutions like VMWare ESXi where you set an entire virtual switch or group of ports in promiscuous mode, in Hyper-V you need to enable monitoring on each switch port individually, for either VM network adapters (vNICs) or host adapters (NICs).įurthermore, Hyper-V does not let you simply set a “promiscuous mode” flag on a port, as you need to specify if a given port is supposed to be the source or the destination of the network packets, “mirroring” the traffic, hence the name. The Hyper-V port monitoring functionality is already well explained elsewhere, so I’ll keep the basics to the minimum here. How does port monitoring / mirroring work? This blog post has the purpose of explaining how to handle non trivial Hyper-V promiscuous mode requirements and introduces a simple PowerShell module to easily handle port monitoring settings on the host. PowerShell APIs, which do a great job in setting up port monitoring between VMs, are quite convoluted and obscure when it comes to host monitoring settings. Hyper-V 2012 introduced the concept of port monitoring (also called port mirroring) which can be enabled on any virtual machine network adapter or on the host. The interesting part is that there’s quite some official documentation available if you want to setup port monitoring / mirroring between two or more VMs, but you are almost on your own if you want to capture traffic coming from an external network or from the host root partition. ![]() A Hyper-V related question that shows regularly up in the forums is how to setup virtual switch ports in promiscuous mode so that external traffic can be received / monitored on the host’s root partition or on virtual machines. ![]()
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