AAA (Authentication, Authorization, and Accounting) is a security
framework that includes application-level network access protocols such as RADIUS,
Diameter, TACACS, and TACACS+.
ActiveMQ is an open-source, message broker from Apache.
An activity map is a dynamic visual representation of the L4-L7 protocol activity
between devices in your network. You can view real-time information about which devices and
services are talking to each other across your network.
Records, packets, activity maps, detections, and charts with L2-L7 protocol metrics are
available for devices receiving this analysis level. Prioritize a group or add a device
to the watchlist to specify which devices should receive Advanced Analysis.
AJP (Apache JServ Protocol) is used for communication between an Apache
web server and an application server.
An alert is a custom configuration of settings, such as a time interval, metric value,
and metric calculations that occur on assigned data sources. An alert is generated when
configured conditions are met. Notifications can be sent through channels such as email or
AMF (Action Message Format) is a format for encoding data transported
between Adobe Flash clients and servers.
The AppFlow protocol was developed by Citrix. This protocol is an extension of the
IPFIX standard for monitoring network traffic. You can collect AppFlow traffic with the
ExtraHop NetFlow module.
In the ExtraHop system, applications are user-defined containers that you can
associate with multiple devices and protocols for a unified view of built-in metrics. These
containers can represent distributed applications on your network environment. You can
create a basic application or an advanced application through the Trigger API. The default
All Activity application is available to all ExtraHop users.
Application Performance Monitoring
Application performance monitoring (APM) tools enable development and application
teams to observe the performance of applications. Data is collected through software agents
that run on application servers, databases, and other application components. The agents can
be configured to gather host-based ingress and egress transaction data, code-level stack
trace inputs, and resource usage metrics such as CPU, memory, and disk.
This ExtraHop chart type displays metric values as a line that connects data points
over time, with the area between the line and axis filled in with color.
Assets are devices and device groups in your environment, as well as related networks,
applications, and users.
Atlas Remote Analysis
Through this service, ExtraHop analysts can perform an unbiased analysis of your
network data and report on areas in your IT infrastructure where improvements can be
(ExtraHop Reveal(x) only) Most network attacks tend to follow familiar patterns or
phases. These phases can be assembled into an attack chain to characterize the progression
of an attack. ExtraHop Reveal(x) detects unusual network behavior associated with different
attack chain phases, including command and control (C&C), reconnaissance, exploit,
lateral movement, and actions on objective.
The audit log on the ExtraHop system provides data about the operations of the
system, broken down by component. For example, when you log in to the ExtraHop system, the
successful or failed event is logged as an entry to the audit log.
This ExtraHop chart type displays the total value of metric data as horizontal
The box plot chart displays variability for a distribution of metric data. Each box
plot includes three or five data points. With five data points, the box plot contains a box,
upper and lower whisker lines, and a tick mark. With three data points, the line contains
upper and lower whisker lines, and a tick mark.
Berkeley Packet Filter (BPF)
Berkeley Packet Filter (BPF) is a program for filtering network packets. The BPF
syntax enables users to write filters that quickly drill down on specific packets to see the
Built-in groups contain devices that are automatically grouped together based on their
network protocol traffic, such as CIFS clients, or by the role assigned to the device, such
as Domain Controllers. A device with multiple types of traffic might appear in more than one
built-in group. You can select built-in groups as a metric source for charts, alerts,
triggers, and activity maps.
Bundles are JSON-formatted documents that contain information about selected system
configuration, such as triggers, dashboards, applications, or alerts. You can create a bundle and then transfer those configurations to
another ExtraHop system, or save the bundle as a backup of your
This ExtraHop chart type displays data calculations for a distribution of metric
values over time. A line at each time interval displays three or five data points. If the
line has five data points, it contains a body, middle tick mark, an upper shadow line, and a
lower shadow line. If the line has three data points, it contains a middle tick
CIFS (Common Internet File System), also known as SMB (Server Message
Block), is an application-level protocol that provides client access to files on a
network attached storage (NAS) repository, typically in a
A client is an application or system that accesses a service made available by a
A group of the same type of ExtraHop appliances that are joined together, such as the
This ExtraHop chart type displays metric values as vertical bars over a specified time
The ExtraHop Command appliance provides a unified view of data collected from sensors
(Discover appliances), recordstores, and packetstores that are distributed across data
centers, branch offices, and the public cloud.
Cross-origin resource sharing (CORS) allows you to access the ExtraHop REST API across
domain-boundaries and from specified web pages without requiring the request to travel
through a proxy server. You can configure one or more allowed origins or you can allow
access to the ExtraHop REST API from any origin. Only administrative users can view and edit
Count metric type
In the ExtraHop system, this top-level metric type represents the number of events
that occurred over a specific time period. You can view count metrics as a rate or a total
A dashboard is a customizable HTML page that displays different views of your network
through widgets such as charts. In addition to custom dashboards, the ExtraHop system
provides the following built-in dashboards: Activity dashboard, Network dashboard, and
Security dashboard (Reveal(x) only).
Relational databases store, retrieve, and manage structured
information through a database management system (DBMS) language.
Dataset metric type
In the ExtraHop system, this top-level metric type represents a distribution of data
that can be calculated into percentiles values.
The ExtraHop system removes duplicate L2 and L3 frames and packets when metrics are
collected and aggregated from your network activity by default. L2 deduplication removes
identical Ethernet frames (where the Ethernet header and the entire IP packet must match);
L3 deduplication removes TCP or UDP packets with identical IP ID fields on the same flow
(where only the IP packet must match).
Detail metrics provide you with a metric value for a specific key, such as a client IP
address, server IP address, URI, hostname, referrer, certificate, or method. When you drill
down from a top-level metric in the ExtraHop system to a detail metric, you can gain insight
into how a specific device, method, or resource is affecting the network.
Detections are unexpected deviations from normal patterns in device or application
behavior. The ExtraHop Machine Learning service identifies detections from stored ExtraHop
system data with a proprietary algorithm that combines time series decomposition,
unsupervised learning, heuristics, and ExtraHop unique domain expertise.
Devices are endpoints in your environment that have been automatically discovered and
classified by the ExtraHop system.
Device discovery is the process by which ExtraHop builds and maintains a list of
active devices associated with monitored network traffic. The ExtraHop system can discover
and track devices by their MAC address (L2 Discovery) or by their IP addresses (L3
Discovery). When L2 Discovery is enabled, the ExtraHop system creates a device entry for
every local MAC address discovered over the wire. IP addresses are mapped to the MAC
address, but metrics are stored with the device MAC address even if the IP address changes.
When L3 Discovery is enabled, the ExtraHop system creates and links two entries for each
local discovered device: an L2 parent entry with a MAC address and an L3 child entry with IP
addresses and the MAC address.
Device groups, also known as custom groups, can be either static or dynamic. You must
manually identify and assign individual devices to a static group. Alternatively, you can
configure rules to automatically assign devices to a dynamic group.
DHCP (Dynamic Host Configuration Protocol) is a protocol for dynamically
distributing network configuration parameters.
DICOM (Digital Imaging and Communications in Medicine) is a standard
for storing biomedical images and transmitting those images over a
The ExtraHop Discover appliance (EDA) is a sensor that provides the ability to analyze
and visualize all of your network, application, client, infrastructure, and business data.
Sensors passively collect a copy of unstructured wire data—all of the transactions on your
network—and transforms this data into structured wire data. Sensors can be connected to
recordstores and packetstores and to an ExtraHop Command appliance or ExtraHop Reveal(x) 360
for centralized management and a unified view of collected and stored data.
Records, packets, detections, and information about protocol activity are available
for devices in Discovery Mode. Adjust analysis priorities to elevate a device or endpoint
from Discovery Mode to Standard or Advanced Analysis.
Distinct count metric type
In the ExtraHop system, this top-level metric type represents the number of unique
events that occurred during a selected time interval. The distinct count metric provides an
estimate of the number of unique items placed into a set during the selected
time interval. Estimates are calculated with the HyperLogLog algorithm.
DNS (Domain Name System) is the naming system for network hosts and resources that are
connected to the Internet. DNS servers map IP addresses to hostnames.
Dynamic baselines are trend lines on dashboards that
help you distinguish between normal and abnormal activity. The ExtraHop system calculates
dynamic baselines based on historical data. To generate data points on a dynamic baseline,
the ExtraHop system calculates the median value for a specified period of time.
Endpoints are internal or external hostnames and IP addresses observed by the ExtraHop
system. Internal endpoints are located on your local or remote network, and external
endpoints are located outside of your local or remote network.
Encapsulated Remote SPAN (ERSPAN) enables you to send source traffic on one switch to
a destination on another switch, while traversing a Layer 3 boundary.
An event represents activity detected from your network or from your ExtraHop system.
Triggers can be written to collect the data associated with an event to create custom
The ExtraHop Explore appliance (EXA) stores transaction and flow records sent from a
connected sensor (Discover appliance). You can view, save, and search the structured flow and transaction information about events on your network with
a simple, unified UI, with no modifications to your existing applications or
A fingerprint is a unique, alphanumeric identifier assigned to all Discover, Explore, and Trace
FIX (Financial Information eXchange) is a protocol that provides
information about the real-time exchange of financial transactions.
A flow is a set of packets that are part of a single transaction between two
endpoints. Similar to how the ExtraHop system can identify flows from wire data, flows from
machine data on remote networks can be sent to the ExtraHop system for analysis. Flows are
identified through their unique combination of IP protocol (TCP/UDP), source and destination
IP addresses, and source and destination ports. This combination is called a
A flow network device can have multiple interfaces. Instead of looking at flow
information for the entire device, you can look at flow information for a specific interface
on the device.
A flow network is a network device that sends information about flows seen across the
device. Similar to how the ExtraHop system can identify flows from wire data, the ExtraHop
system can receive flow information from remote network devices, also called flow
A Flow Stall is a TCP metric in the ExtraHop system that measures network congestion.
A Flow Stall is counted when there are three consecutive retransmission timeouts (RTOs)
observed on a single flow of data between devices. An RTO represents a 1-5 second delay as a
device waits to resend data that might have been lost over a congested
FTP (File Transfer Protocol) is a standard network protocol for
transferring files between a client and a server.
Goodput refers to the amount of useful data that is transferred over the L4
application layer per unit time. In this context, useful means that retransmissions are
discarded as duplicate packets along with any protocol overhead or other non-application
data found on the wire. Goodput is always lower than the throughput, and roughly corresponds
to the size of the payload bytes for any protocol running on TCP (such as a CIFS file or
HTTP request) over the transfer time.
This ExtraHop chart type displays a distribution of metric data over time, where color
represents a concentration of data.
This ExtraHop chart type displays a distribution of metric data as vertical bars, or
HL7 (Health Level-7) is a standard for exchanging electronic health
information between software applications.
HTTP (Hypertext Transfer Protocol) is an application-level protocol that
retrieves web pages.
IBM MQ is a message-queuing protocol for IBM enterprise and message
ICA (Independent Computing Architecture) is a Citrix system protocol that
transmits data between clients and servers.
ICMP (Internet Control Message Protocol) is a protocol that network devices send error
and query messages through.
The Integrated Dell Remote Access Controller (iDRAC) provides remote access to
ExtraHop appliances. After you enable and configure iDRAC, you can power cycle the system,
view console messages, and review hardware monitoring and boot logs.
iSCSI (Internet Small Computer Systems Interface) is a TCP-level
protocol that allows SCSI commands to be sent over a local-area network (LAN) or
wide-area network (WAN).
Kerberos is a security protocol that applies secret-key cryptography
to client and server authentication.
The data link layer in the OSI model. In the ExtraHop system, L2 metrics
provide information about the connection between two devices.
The network layer in the OSI model. In the ExtraHop system, L3 metrics provide IP
address information for nodes that communicate over the monitored network.
The transport layer in the OSI model. In the ExtraHop system, L4 TCP
(Transmission Control Protocol) metrics provide information about the reliable transfer
of packets between a source and destination.
The application layer in the OSI model. In the ExtraHop system, L7 metrics
provide information about interactivity with software applications.
LDAP (Lightweight Directory Access Protocol) is a vendor-neutral
protocol that maintains and provides easy access to a distributed
A level-triggered alert is generated at specified intervals for as long as the metric
value remains above the configured threshold.
This ExtraHop chart type displays metric values as a line, which connects a series of
data points over time.
Line & column chart
This ExtraHop chart type displays metric values as a line, which connects data points
over time, with the option to display another metric as a column chart
This ExtraHop chart displays metric values in a list across multiple columns with
The Link Layer Discovery Protocol (LLDP) is a protocol that network devices
communicate their identity and capabilities through.
LLMNR (Link-Local Multicast Name Resolution) is a protocol that is
included in Microsoft Window systems. This protocol is based on the Domain Name System
(DNS) format and enables name resolution for hosts on the same local link when DNS name
Maximum metric type
In the ExtraHop system, this top-level metric type is a single data point that
represents the maximum value from a specified time period.
Memcache is a protocol that provides access to high-performance,
distributed memory object caching systems over a TCP connection.
In the ExtraHop system, a metric is a measurement of observed network behavior.
Metrics are generated from network traffic, and then each metric is associated with a
source. The ExtraHop system provides built-in, or default, metrics based on observed network
traffic from wire data. You can also create custom metrics in the ExtraHop system by writing
a trigger to collect metrics based on a specific event.
The Metric Catalog is a tool for viewing information about built-in and custom metrics
in the ExtraHop system. You also can delete and edit custom metrics through the Metric
The Metric Explorer is a tool for configuring dashboard charts. In the Metric
Explorer, you can add multiple sources and metrics to a chart and immediately preview how
metric data will appear.
Modbus is a serial communication protocol used in industrial
MongoDB is an open-source document database that provides
performance, availability, and scalability.
MSMQ (Microsoft Message Queuing) is a protocol that enables applications
to send messages and objects to each other.
Acronym for not a number. In the Trigger API, a property with a numeric data
type displays NaN if the property value is undefined or cannot be
represented as a number.
NAS (Network Attached Storage) is a file-level storage repository.
Clients can access the repository through SMB (Server Message Block) or NFS (Network
File System) protocols.
NBNS or NBT-NS (NetBIOS Name Service) is a naming system for network
hosts and resources.
Flow technologies such as Netflow, IPFIX, sFlow, and AppFlow collect
traffic data from flow networks outside your wire data feed and send the data to the
sensor (Discover appliance) for analysis.
In the ExtraHop system, a network is the entry point into the network capture, and
metrics are collected for network capture attributes, network alerts, and network traffic
details. These metrics provide a summary of all network activity retrieved in the
A network byte is a metric that displays the throughput rate of the ExtraHop capture
Network health indicators
(ExtraHop Reveal(x) only) Network health indicators are a set of metrics that show you
general trends related to network and security health. Network health indicators might
signal weaknesses or issues in network performance or potentially suspicious activity. These
metrics can be found at the bottom of the Network Overview page.
NFS (Network File System) is a distributed file system protocol that
provides client access to files on a network attached storage (NAS) repository,
typically in a UNIX environment.
An individual ExtraHop appliance within a cluster.
Open Data Stream
The open data stream (ODS) service enables you to send wire data to a remote
third-party system, such as MongoDB or Kafka. You must write a trigger to identify and
collect the data you want to export and configure settings through the ExtraHop
The Packets feature enables you to search for and download packets for selected
transactions through a sensor (Discover appliance), Command appliance or Reveal(x) 360. This
feature requires an ExtraHop Trace appliance or other supported packetstore.
You can configure a sensor (Discover appliance) to send raw packets to an ExtraHop
Trace appliance or to a configured packet capture disk for long-term storage and
Participants are endpoints that are participating as an offender or victim in a
Perfect Forward Secrecy (PFS)
Perfect Forward Secrecy (PFS) is an encryption method that enables short-term,
completely private key exchanges between clients and servers. You can license the ExtraHop system to decrypt PFS SSL/TLS sessions from Windows servers where the ExtraHop PFS agent
software is installed. Without PFS, those sessions could not be decrypted, and the data from
those exchanges would be obscured.
PCAP (packet capture) consists of an application programming interface (API) for
capturing network traffic and storing it to a database.
PCoIP (PC-over-IP) is a protocol that transfers compressed and
encrypted image pixels from a central server to a PCoIP device.
This ExtraHop chart displays metric data as a portion or percentage of a
POP3 (Post Office Protocol) is a standard application-level protocol
that transfers email messages between a server and a client application over a TCP
Port mirroring occurs when a network switch sends a copy of network packets from one
switch port (or an entire VLAN) to a network monitoring connection on another switch
A protocol defines the format and the order of messages exchanged between two or more
devices, as well as the actions taken on the transmission and receipt of a message or other
A protocol page is a built-in page that includes built-in charts with top-level
metrics about your assets. These metric charts can be copied to your dashboards.
RDP (Remote Desktop Protocol) is a proprietary Microsoft protocol for
communicating between a Remote Desktop Session Host server and a client running Remote
Desktop Connections software. RDP is encapsulated and encrypted within
Records are structured flow and transaction information about events on your network
that can be sent to an Explore appliance or other supported recordstore for storage. Then,
you can query for records from a sensor (Discover appliance), Command appliance, or
A record format is a schema on read that determines how each record is displayed in
the ExtraHop system. The ExtraHop system has built-in record formats for all built-in record
types, and although you cannot modify a built-in record format, you can create a custom
Record types link stored records with the record format in the ExtraHop system.
Requires an Explore appliance or other supported recordstore.
You can configure a sensor (Discover appliance) to send transaction-level data to an
Explore appliance or to a data warehouse for long-term storage and retrieval. ExtraHop Cloud
Recordstore is provided for Reveal(x) 360. Supported third-party data warehouses include
Google BigQuery and Splunk.
Redis is an open-source, data structure server.
A region is a dashboard component that contains
Retransmission Timeout (RTO)
A retransmission timeout (RTO) is a TCP protocol metric for determining network
performance. TCP retransmissions occur on the network frequently. TCP starts a
retransmission timer when an outbound segment is handed down to an IP address. If there is
no acknowledgment (ACK) before the timer expires, the segment is retransmitted. An RTO
occurs when the sender begins missing too many acknowledgments and stops sending segments
for a period of time. RTOs can represent a 1-5 second delay on your network. Multiple RTOs
over time can represent significant delays on your network.
Reveal(x) 360 provides SaaS-based visibility and management across on-premises and
cloud-based connected environments. The Reveal(x) 360 console provides a single view of data
collected from multiple sensors (ExtraHop Discover appliances), packetstores, and
recordstores, which can be distributed across data centers, branch offices, and the public
Reveal(x) Enterprise is a subscription-based offering of ExtraHop products that
include a sensor (ExtraHop Discover appliance) to collect wire data and additional
components based on the plan type.
RFB (remote framebuffer) is a protocol for remote access to a graphical
user interface that allows a client to view and control a system on another
(ExtraHop Reveal(x) only) A risk score is a numeric indicator of the severity of a
detection. Risk scores are based on several factors, such as where the detection falls in
the attack chain, the vulnerability of the detection protocol, and the level of impact the
detection could have on the network. Scoring is on a scale from 1-99, with 99 being the most
MRPC (Microsoft Remote Procedure Call) is a communication mechanism for
clients to call a procedure from a program located on another computer, server, or
Remote packet capture (RPCAP)
Remote packet capture (RPCAP) is a software implementation for packet forwarding that
is similar to a physical tap. If you want to monitor network traffic for devices that are
not directly connected to your wire data feed, you can forward packets through the cloud and
analyze that data through the ExtraHop system.
Remote Switched Port Analyzer (RSPAN) provides remote monitoring of multiple switches
across a switched network. RSPAN is a way to get traffic from a SPAN source on one switch to
a SPAN destination on another switch that is connected via a trunk.
that the source and destination chassis are in the same Layer 2
RTCP (Real-time Transport Control Protocol) is a protocol that monitors
statistics for streaming audio and video data transferred by the RTP
RTP (Real-time Transport) is a protocol that defines the standardized
packet format for the real-time transfer of streaming audio and video.
The debug log is a component of the Trigger Editor in the ExtraHop system. The debug
log displays exceptions and output from debug statements in trigger scripts.
Sampleset metric type
In the ExtraHop system, this top-level metric type represents a summary of data that
provides a mean (average) and standard deviation over a specified time period. Sampleset
metrics typically summarize data about a detail metric.
The Session Description Protocol (SDP) is a protocol that defines multimedia streaming
A server is a hardware system dedicated to hosting one or more services for users or
clients on the network. In the context of Internet Protocol (IP) networking, a server is a
program that operates as a socket listener.
SIP (Session Initiation Protocol) is a signaling protocol that controls
communication sessions, such as voice calls for IP-based telephony
A site is a wire data feed analyzed by the ExtraHop system that represents a physical
or logical area of your network, such as a data center, branch office, or cloud workload.
You can view assets, detections, and other data from a specific site or across multiple
SMPP (Short Messaging Peer-to-Peer) is an application-level protocol
that transfers Short Message Service (SMS) data between External Short Messaging
Entities (ESME) and Short Message Service Centers (SMSC).
SMTP (Simple Mail Transfer Protocol) is a standard protocol that sends,
receives, and relays email messages between servers, email transfer agents, and client
Snapshot metric type
In the ExtraHop system, this top-level metric type represents a data point that
represents a single point in time. Snapshot metrics include ratios, current connections, and
established TCP connections.
The Simple Network Management Protocol (SNMP) is a layer-7 protocol for collecting,
organizing, exchanging, and modifying information about managed devices on IP
Sources are assets that can be assigned to charts, triggers, and alerts to provide
access to metric collections.
Port mirroring on a Cisco Systems switch is generally referred to as Switched Port
Analyzer (SPAN). SPAN copies traffic and sends it to a destination for network
Secure Shell (SSH) is a protocol that securely transmits information over
SSL (Secure Sockets Layer) is a standard protocol for securing
communication over the Internet. To establish an encrypted link between a web browser
and a server, the server must have an SSL certificate.
Records, packets, detections, activity maps, protocol activity, and charts with
throughput and packet metrics are available for devices receiving Standard Analysis. Adjust
analysis priorities to elevate a device or endpoint from Standard Analysis to Advanced
This ExtraHop chart type displays metric values in a column chart, where the color of
the columns represents the status and severity of an alert assigned to the source and metric
selected in the chart.
(ExtraHop Reveal(x) only) Structured Threat Information eXpression (STIX) is the
language and serialization format for standardizing, conveying, and sharing data about cyber
threat intelligence data. The STIX format is commonly supported by the threat intelligence
community and platforms. You can upload STIX files through the ExtraHop system or the REST
API as a custom threat collection. Custom threat collections must be formatted in STIX as
TAR or TAR.GZ files.
This ExtraHop chart type displays metric values across rows and columns in a
In the ExtraHop system, TCP (Transmission Control Protocol) metrics provide
information about the reliable transfer of packets between a source and destination. Through
TCP metrics, ExtraHop provides visibility into which devices are connected to each other,
when devices send data, if there are errors in the data, what protocols are communicated
through, and so on.
A TCP RST packet is sent to prevent a TCP connection from being established or to
forcibly terminate an existing connection. Sometimes resets are sent when the receiving
device failed to ACK the SYN packet, or it failed to acknowledge another packet sent and
retransmitted later in the transaction. In some cases, TRCP RSTs indicates that an error
occurred. High volumes of outbound resets should be investigated to determine if they are
expected behavior or indicative of a larger issue.
Telnet is an application-layer protocol for interactive text-oriented
communications over a virtual terminal connection.
(ExtraHop Reveal(x) only) A threat collection is a data set of suspicious IP
addresses, hostnames, and URIs that enables your Reveal(x) system to identify indicators of
compromise and display threat intelligence in system charts and records.
Threat intelligence is known data about suspicious IP addresses, hostnames, and URIs
that can help identify risks to your organization. These data sets, called threat
collections, are available by default in your Reveal(x) system and from free and commercial
sources in the security community.
The Time Selector is a tool that enables you to specify a time interval for the
collection and presentation of network data in the ExtraHop system. There are two types of
Time Selectors: a Global Time Selector for specifying global time intervals and a Region
Time Selector for specifying region time intervals in a dashboard.
A timestamp is a digital record of the time a particular event occurred. In the
ExtraHop system, you can select the default timestamp, or configure external timestamps such
as Gigamon or Anue through the Running Configuration file.
A tinygram is a small packet or TCP segment. A tinygram is a packet where the payload
is smaller than the frame header (L2-L4) data. In general, tinygrams lead to inefficient
ratios of frame header data to actual useful information going across the network. Tinygrams
can contribute to network congestion.
A top-level, or base, metric gives you a sum of data for a specified time period.
Top-level metrics provide you with a big-picture value to help identify what is happening on
your network. You can then drill down on a top-level metric to view detail metrics. There
are different types of top-level metrics that provide different information, which include
count, dataset, maximum, sampleset, and snapshot metric types. Understanding metrics types
is essential to writing triggers and configuring charts.
A topnset is the top 1,000 key-value pairs calculated for the time interval you
specify in the Time Selector. A topnset is not a complete data set because a topnset only
represents the key-values that are recorded for a specific aggregation roll up (based on a
specified time interval), and is limited to up to 1,000 keys per topnset.
The ExtraHop Trace appliance (ETA) continuously collects network packets and connects
to a sensor (ExtraHop Discover appliance) to enable you to quickly retrieve all packets that
match a set of search criteria within a given time interval.
Triggers are custom scripts that perform an action upon a pre-defined event. For
example, you can write a trigger to record a custom metric every time an HTTP request
occurs, or to classify traffic for a particular server as an application server.
The ExtraHop Reveal(x) Ultra appliance combines the functions of a sensor (Discover
appliance) and a Trace appliance to both analyze and collect your network data and to store
This ExtraHop chart displays the total value for one or more metrics. Selecting more
than one metric will display the metric values side-by-side.
Virtual packet loss
Virtual packet loss (VPL) refers to a phenomenon that affects fully or partially
virtualized applications. VPL creates symptoms that suggests network congestion and is
often undetected by traditional network monitoring and application performance
management (APM) tools. VPL occurs when a hypervisor schedules CPU time for an excessive
number of virtual machines (VMs) and prevents those VMs from responding fast enough to
TCP acknowledgments. VPL can be detected by a combination of application awareness and
advanced TCP analysis.
A Virtual Local Area Network (VLAN) is a logical grouping of traffic or devices on a
network. VLAN information is extracted from VLAN tags, if the traffic mirroring process
preserves the tags on the mirror port.
Vulnerability scanners are programs that search
applications, systems, and networks for weaknesses. In the ExtraHop system, a device
that sends HTTP requests associated with known scanner activity is assigned the
Vulnerability Scanner role. You can also manually designate a device as a scanner by
changing the device role to Vulnerability Scanner.
Individual devices on the watchlist are guaranteed Advanced Analysis. Typically,
high-value endpoints are added to the watchlist. Advanced Analysis is an analysis level where
records, packets, activity maps, and charts with L2-L7 protocol metrics are available for
devices. You can remove devices from the watchlist at any time.
Widgets are configurable dashboard components that can
be added to a region for different functions. Widget types are chart, text box, alert,
activity groups, and networks (Command appliance and Reveal(x) 360 only).
Wire data is created when data in flight is analyzed as traffic is sent over the
network. Through real-time full-stream processing, unstructured data is reassembled into
structured wire data that can be analyzed in real time. Wire data encompasses L2-L7 data
that spans the entire application delivery chain and provides the most comprehensive,
WMI (Windows Management Instrumentation) is a set of Windows system
extensions that provides an operating system interface for establishing remote access
WSMAN (Web Services Management) protocol is a public standard for
exchanging data with any computer device.
A Zero Window is a TCP metric in the ExtraHop system that measures application
congestion. When a device advertises a Zero Window message to the sender device during data
transfer, this means that the device can no longer accept data because the device's receive
window (a buffer for incoming data) is full. The Zero Window message tells the sender to
pause data transfer until further notice.