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.
Activity groups contain devices that are automatically grouped together based on their
network traffic. A device with multiple types of traffic might appear in more than one
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 critical assets 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 condition that establishes baseline values for specified metrics. If
those values are exceeded, the system logs the event and sends notifications through
configured channels (such as email or SNMP). The Discover appliance includes built-in alerts
and you can also create custom alerts.
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. In the
ExtraHop system, you can create a basic application through the Web UI or an advanced
application through the Trigger API. A default application that is available to all ExtraHop
users is the All Activity application.
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.
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 Discover appliance provides data about the operations of the
system, broken down by component. For example, when you log into an ExtraHop appliance, 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
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 appliance, 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 Windows environment.
A client is an application or system that accesses a service made available by a
A group of the same ExtraHop appliances that are joined together.
This ExtraHop chart type displays metric values as vertical bars over a specified time
The ExtraHop Command appliance (ECA)
provides centralized management of connected ExtraHop Discover appliances. The ECA provides a
single view of data collected from multiple ExtraHop Discover, Explore, and Trace
appliances, which can be distributed across data centers, branch offices, and the public
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 critical asset is a device that is important to your network or business, such as a
database, a storage server, an AAA server, a DNS server, or an executive's laptop. You can
prioritize critical assets for Advanced Analysis by adding a device to the watchlist or
prioritizing a group on the Analysis Priorities page.
A dashboard is a customizable HTML page that displays different views of your network
through widgets such as charts. In addition to custom dashboards, there are two built-in
system dashboards that provide charts: the Activity dashboard and the Network
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 (formerly called Anomalies) are unexpected deviations from normal patterns
in device or application behavior. The ExtraHop Machine Learning service identifies
detections from stored Discover appliance data with a proprietary algorithm that combines
time series decomposition, unsupervised learning, heuristics, and ExtraHop's unique domain
Devices are objects on your network that have been automatically discovered and
classified by the ExtraHop system. The ExtraHop system collects records and packets for
every discovered device on your network. You can analyze metrics and activity maps for
devices that are receiving Standard Analysis and Advanced Analysis.
Device discovery is the process by which ExtraHop builds and maintains a list of
active devices associated with monitored network traffic. When the ExtraHop system detects a
MAC address on the network, a L2 device entry is created in the ExtraHop system and
associated with that address. When the ExtraHop system detects an ARP (Address Response
Protocol) response, an L3 device entry is created in the ExtraHop system and associated with
the MAC address and IP address. Based on the type of traffic, the ExtraHop system also
classifies the device type and assigns a name to the device. For example, an L2 device can
be a gateway device or router. L3 devices can be clients, servers, or databases. You can
also create a custom device in the ExtraHop system to monitor traffic for a specific IP
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)
provides the ability to analyze and visualize all of your network, application, client,
infrastructure, and business data. The EDA passively collects a copy of unstructured wire
data—all of the transactions on your network—and transforms this data into structured wire
data. EDAs can be connected to the ExtraHop Command appliance for centralized
management and connected to ExtraHop Trace and Explore appliances for data collection and
Records, packets, 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 HyperLogLog set during the selected
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. Discover appliances calculate
dynamic baselines based on historical data. To generate data points on a dynamic baseline,
an appliance calculates the median value for a specified period of time.
An endpoint typically refers to a device, which is an object on your network that has
been automatically discovered and classified by the ExtraHop system. You can find endpoint
information, such as IP address and port, in different locations in the ExtraHop system. For
example, you can find the IP address for a device on the Device Overview page. You can find
a port associated with an IP address or transaction on a detail metric page or in a
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 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 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 a Discover appliance 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 middleware products.
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
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 resolution fails.
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
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 builtin, 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 ExtraHop 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 indiviudal 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 in the ExtraHop Admin
The Packets feature enables you to search for and download packets for selected
transactions through a Discover or Command appliance. This feature requires an ExtraHop
You can configure the Discover appliance to send raw packets to an ExtraHop Trace
appliance or to a configured packet capture disk for long-term storage and
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 a Discover
appliance 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 connection.
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 in the ExtraHop Web UI. You can access a protocol
page in the by logging into the Web UI, clicking Assets, and then
clicking the name of a source or group; all protocol pages for the source or group are
listed in the left column.
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 third-party recordstore for storage. Then, you
can query for records from Discover or Command appliances.
A record format is a schema on read that determines how each record displays in the
Web UI. The Discover and Command appliances have 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 format.
Record types link stored records with the record format in the Web UI. Requires an
Explore appliance or third-party recordstore.
You can configure the Discover appliance to send transaction-level data to an ExtraHop
Explore appliance or to a third-party cloud data warehouse (such as Splunk or BigQuery) for
long-term storage and retrieval.
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.
ExtraHop Reveal(x) offers network security analytics driven by machine learning to
provide visibility into critical assets and automate investigations for security teams.
Reveal(x) passively collects a copy of your unstructured wire data—all of the transactions
on your network—and transforms this data into structured wire data. Depending on your
subscription, Reveal(x) solutions include an ExtraHop Discover appliance to collect wire
data, an ExtraHop Command appliance for centralized management, and ExtraHop Trace and
Explore appliances for data collection, storage, and retrieval.
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
(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 severe.
MRPC (Microsoft Remote Procedure Call) is a communication mechanism
for clients to call a procedure from a program located on another computer, server,
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 Discover appliance.
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
The debug log is a component of the Trigger Editor in the ExtraHop Web UI. The
debug log displays exceptions and output from debug statements in trigger
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
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 applications.
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
In the ExtraHop system, a source provides access to collections of metrics. A source
is an application, device (including device groups), or network (including
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 a network.
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, 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 Web UI or REST API of your Discover or Command appliances
as a custom threat collection. Custom threat collections must be formatted in STIX as TAR or
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 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 Web UI. 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 the ExtraHop Discover appliance to enable you to
quickly retrieve all packets that match a set of search criteria within a given time
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.
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 acknowledgements. 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,
critical assets 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 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
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.