Glossary
E
86 terms.
- E.164
The international standard for telephone numbering, administered by the ITU. It defines how country codes, area codes, and local numbers are structured.
Like I'm five The system for writing phone numbers consistently around the world, like +1-555-1234.
- E.164 Number
An international public telephone number in the format defined by ITU Recommendation E.164. ENUM turns such numbers into domain names.
Like I'm five A full phone number, including the country code, that works anywhere in the world.
- E.164 number
A telephone number in the international public numbering format defined by the ITU-T. ENUM writes it with a leading plus sign followed by digits.
Like I'm five A full phone number including the country code, the same for everyone in the world.
Used in RFC 3026 RFC 3761 RFC 4002 RFC 4355 RFC 4414 RFC 4759 RFC 7195
- EAP
The Extensible Authentication Protocol. A framework for login methods such as passwords. IKEv2 can carry EAP messages to authenticate the initiator, alongside certificate-based authentication of the responder.
Like I'm five A way to ask for a username and password before letting someone in.
Used in RFC 2284 RFC 2477 RFC 2607 RFC 2809 RFC 2869 RFC 2989 RFC 3127 RFC 3169 RFC 3579 RFC 3580 RFC 3588 RFC 3748 RFC 3770 RFC 4016 RFC 4017 RFC 4058 RFC 4072 RFC 4137 RFC 4186 RFC 4187 RFC 4282 RFC 4284 RFC 4296 RFC 4297 and 93 more
- Early dialog
A SIP dialog created when a non-100 provisional response is sent to an initial dialog-initiating request. It stays in early state until a final response is sent.
Like I'm five A phone call attempt that has started ringing but has not been answered or refused yet.
- Early media
Audio, video, or other media transmitted before a call is answered (before the called party sends a 200 OK response), such as ringing tones or announcements.
Like I'm five Sounds you hear before the other person picks up.
Used in RFC 3398 RFC 3666 RFC 3725 RFC 3959 RFC 3960 RFC 5009
- EBCDIC
Extended Binary Coded Decimal Interchange Code, a character encoding used on IBM systems that differs from ASCII.
Like I'm five IBM's own alphabet code, different from the one most computers use.
- ECCSI
Elliptic Curve-based Certificateless Signatures for Identity-based Encryption. A digital signature scheme that works with identity-based keys and does not require certificates.
Like I'm five A way to prove you sent a message using math instead of a certificate.
- ECDHE
Elliptic Curve Diffie-Hellman with Ephemeral keys. Both sides use fresh elliptic curve key pairs for each exchange, so a later key leak does not expose past sessions.
Like I'm five Making a brand-new secret code for each conversation and throwing it away afterwards.
- ECDSA
The Elliptic Curve Digital Signature Algorithm, a way to sign data with an elliptic curve private key so others can verify it with the public key.
Like I'm five A way to sign your name so that anyone can check it is really yours.
Used in RFC 3278 RFC 4492 RFC 4754 RFC 5008 RFC 5430 RFC 5759 RFC 6460 RFC 6637 RFC 7427 RFC 8374 RFC 8608 RFC 8812 RFC 9966
- Ed25519
A digital signature scheme from the EdDSA family, defined in RFC 8032, that uses 32-byte public keys and produces 64-byte signatures.
Like I'm five A way of signing messages so anyone can check the signature but only the key owner could have made it.
- EdDSA
The Edwards-curve Digital Signature Algorithm, a public-key signature scheme described in RFC 8032. It is used with curves such as Ed25519 and Ed448.
Like I'm five A modern way to sign something so others can tell it is really yours.
- EDNS(0)
The Extension Mechanisms for DNS, version 0. A way to attach an OPT record to a DNS message to advertise UDP size, flags and options.
Like I'm five A sticky note on a question that says what the sender can handle.
Used in RFC 6891 RFC 7314 RFC 8109 RFC 8499 RFC 8767 RFC 8906 RFC 9609
- EDNS0
Extension Mechanisms for DNS. It allows larger DNS messages and carries extra flags such as the DO bit, which DNSSEC requires.
Like I'm five A bigger envelope with room for extra labels.
Used in RFC 2671 RFC 2672 RFC 2673 RFC 3225 RFC 3226 RFC 3755 RFC 4033 RFC 4035 RFC 5001 RFC 5358 RFC 5395 RFC 5625 RFC 5936 RFC 5966 RFC 6895 RFC 6975 RFC 7720 RFC 7766 RFC 7828 RFC 7830 RFC 7871 RFC 7873 RFC 7901 RFC 8027 and 22 more
- Egress Peer Engineering
Using SIDs for BGP peers (PeerNode, PeerSet and Peer Adjacency SIDs) so that traffic can be steered out of a network through a chosen neighbor.
Like I'm five Choosing which exit door traffic uses when leaving the network.
- Electronic Data Interchange
A way for trading partners to exchange structured business transactions electronically, using agreed formats such as X12 or EDIFACT in place of paper documents.
Like I'm five Business forms like orders and invoices sent between computers instead of by post.
- Electronic wallet
Software that stores a person's billing, shipping and payment information and uses it to complete online forms automatically.
Like I'm five A helper program that remembers your details and fills in forms for you.
- Elliptic curve
A curve defined by an equation such as y^2 = x^3 + a*x + b. Its points can be added together, which gives a group used in public-key cryptography.
Like I'm five A special curve where you can add points together, and the math is hard to undo.
Used in RFC 5349 RFC 5832 RFC 6539 RFC 6932 RFC 7091 RFC 7664 RFC 7748 RFC 8121 RFC 8133 RFC 8812 RFC 9383 RFC 9385
- Elliptic Curve Cryptography
A family of public-key cryptography methods based on elliptic curves. In TLS it is used for key exchange and digital signatures.
Like I'm five A way to make secret handshakes using special curved math that stays small and quick.
Used in RFC 3279 RFC 4492 RFC 4753 RFC 5289 RFC 5656 RFC 5753 RFC 5759 RFC 6090 RFC 6637 RFC 6954 RFC 8422
- Elliptic Curve Diffie-Hellman
A key agreement protocol based on elliptic curve mathematics where two parties each contribute a private key and derive a shared secret without transmitting it.
Like I'm five Two people pick secret numbers on a curve and exchange public information, then both compute the same shared secret.
- Elliptic curve group
A set of points on an elliptic curve, together with a rule for combining points. Diffie-Hellman key exchange can be run in such a group instead of in modular exponentiation.
Like I'm five A special kind of number playground where two people can mix their secrets and end up with the same answer.
- Empty non-terminal
A domain name that owns no resource records itself but has subdomains that do. Such a name still exists.
Like I'm five A folder with nothing in it except other folders that hold files.
- EMSK
The Extended Master Session Key, a key derived by a key-generating EAP method alongside the MSK. It is reserved for deriving root keys and cannot leave the EAP server.
Like I'm five A master key that stays locked in the main office and is only used to make smaller keys.
- Encapsulation
Wrapping a complete network packet inside another packet to redirect it through a different path or network layer.
Like I'm five Putting a whole message inside another message envelope so it travels a different route.
Used in RFC 1044 RFC 1088 RFC 1234 RFC 1241 RFC 1454 RFC 1933 RFC 2003 RFC 2157 RFC 2473 RFC 2784 RFC 2895 RFC 3056 RFC 3507 RFC 3821 RFC 4459 RFC 5512 RFC 5579 RFC 7059 RFC 7341 RFC 9599
- Encoded-word
A sequence of printable ASCII characters in a mail header that starts with =? and ends with ?=. It names a character set and an encoding and carries the text in encoded form.
Like I'm five A secret-code label that hides fancy letters inside plain ones.
- Encoding Symbol
The unit of data carried in a packet by a forward error correction scheme. It is either an original source symbol or a redundant repair symbol made from the source block.
Like I'm five One piece of the puzzle, or a spare piece, that goes in a packet.
- Encrypted Client Hello (ECH)
A TLS extension, defined in RFC 9849, that encrypts the real ClientHello inside an outer ClientHello so that the server name and other fields are hidden from the network.
Like I'm five A sealed envelope inside a plain one, so people along the way can't read who the letter is really for.
- Encryption
The process of converting information into a form (ciphertext) that cannot be easily understood by unauthorized parties, using a mathematical algorithm and a key.
Like I'm five Scrambling a message so only someone with the right key can read it.
- Enctype
Short for encryption type in Kerberos. It names the cryptosystem used to protect a key or a message, such as the one used for a ticket session key.
Like I'm five The name of the secret-code method two sides use to lock their messages.
- End-entity certificate
A certificate that identifies the signer of a particular object rather than another certificate authority. In RPKI signed objects, one such certificate is embedded to validate the signature.
Like I'm five The signer's ID card that travels with the signed note.
- End-to-end principle
The argument that certain functions can only be performed correctly by the end systems themselves, so the network should just move datagrams and leave everything else to the fringes. It is described in Saltzer, Reed and Clark (1984) and cited in RFC 1958.
Like I'm five The road only carries the box; the two people at the ends check that it arrived.
Used in RFC 817 RFC 1958 RFC 2316 RFC 2480 RFC 2775 RFC 2804 RFC 3102 RFC 3135 RFC 3155 RFC 3234 RFC 3238 RFC 3439 RFC 3724 RFC 3819 RFC 3837 RFC 3838 RFC 4189 RFC 4225 RFC 4924 RFC 6346 RFC 8280 RFC 8557 RFC 8558 RFC 8576 and 6 more
- End-to-end transparency
The ability for a packet to flow from any source to any destination with its contents and addressing unmodified by intermediate devices.
Like I'm five Packets travel directly from sender to receiver without any middle machine changing their addresses.
- Endpoint ID (EID)
In LISP, an address that identifies an endpoint within a site. It is kept separate from the Routing Locators used on transit networks.
Like I'm five A kid's permanent name, which stays the same wherever they go.
- Endpoint Identifier
A LISP identifier for an endpoint, used to say who it is rather than where it is attached to the network.
Like I'm five A name tag that stays the same wherever you go.
- Endpoint Identifier (EID)
In LISP, the address that identifies what a computer is, its identity, independent of its location in the network.
Like I'm five The address that identifies who a computer is, separate from where it is.
Used in RFC 1753 RFC 4838 RFC 5558 RFC 6139 RFC 6259 RFC 6260 RFC 6316 RFC 6830 RFC 6832 RFC 6836 RFC 6837 RFC 7834 RFC 7835 RFC 7954 RFC 7955 RFC 8060 RFC 8111 RFC 9299 RFC 9300 RFC 9735 RFC 9758 RFC 9962
- Endpoint-independent mapping
A NAT behavior in which an internal address and port always get the same external address and port, no matter which external host they connect to.
Like I'm five You get the same return address on every letter, no matter who you write to.
- Energy Object
A device, or a component of a device, whose power use or energy use can be monitored or managed. It is identified by its physical index in the ENTITY-MIB.
Like I'm five Any gadget or part of a gadget that uses electricity and can report about it.
- Enforcement Point
A node on an access network that applies filters to traffic from and to client devices. It lets only allowed traffic through until the client has been authorized.
Like I'm five A door guard who only lets people in once the front desk says yes.
- Enhanced status code
A three-part code of the form class.subject.detail, such as 5.1.1, that gives a precise and translatable reason for the result of a mail operation.
Like I'm five A short number label that tells exactly why a letter was or was not delivered.
- Enterprise number
A 32-bit integer assigned by IANA that uniquely identifies an organization. Protocols use it to say whose vendor-specific data follows.
Like I'm five A company's official ID number, used to show whose note it is.
- Entity Attestation Token
A token, defined in RFC 9711, that carries claims about a device or other entity so that remote attestation messages can be conveyed in a standard format.
Like I'm five A sealed note that says things about a device so others can check it.
- Entity body
The content carried by an HTTP message, such as an HTML page. It follows the headers after a blank line and is described by entity headers like Content-Type and Content-Length.
Like I'm five The actual page inside the envelope.
Used in RFC 1945
- Entropy
A measure of how unpredictable a secret value is, counted in bits. A value drawn evenly from 2^n possibilities has n bits, and an attacker must try about half of them. Min-entropy, which looks at the single most likely value, is the safest measure for security.
Like I'm five How surprising something is. The more ways it could have turned out, the harder it is to guess.
Used in RFC 2777 RFC 3211 RFC 3526 RFC 3562 RFC 3766 RFC 3797 RFC 4086 RFC 4467 RFC 4537 RFC 4552 RFC 4615 RFC 4738 RFC 5869 RFC 5959 RFC 6386 RFC 6391 RFC 7199 RFC 7447 RFC 7613 RFC 7636 RFC 8065 RFC 8086 RFC 8296 RFC 8469 and 13 more
- Entropy label
An extra MPLS label holding a hash of packet fields, computed once by the ingress router. Transit routers can use it for load-balancing without looking deeper into the packet.
Like I'm five A quick number written on the front of a package so helpers can sort it without opening it.
- Entropy pool
A buffer of bits that an operating system keeps for random numbers. New unpredictable events are strongly mixed in, random bytes are extracted by hashing it, and its state is often saved at shutdown and restored at start-up.
Like I'm five A jar where the computer drops in little surprises and scoops out random numbers when asked.
Used in RFC 4086
- ENUM
The system that maps phone numbers (E.164 format) to internet addresses and other resources via DNS.
Like I'm five A phone book that lives on the internet and helps find where to send a call.
Used in RFC 3026 RFC 3764 RFC 3824 RFC 4114 RFC 4414 RFC 4415 RFC 4759 RFC 4769 RFC 5067 RFC 5076 RFC 5333 RFC 5346 RFC 5483 RFC 6118
- Enumservice
A registered label in the Services field of an ENUM NAPTR that says what kind of interaction the resulting URI supports, such as voice or sms.
Like I'm five A tag that says what you can do with the address, like call it or text it.
Used in RFC 3762 RFC 3953 RFC 4002 RFC 4143 RFC 4355 RFC 4415 RFC 4769 RFC 4969 RFC 4979 RFC 5028 RFC 5278 RFC 5333 RFC 5483 RFC 6116 RFC 6117 RFC 6118 RFC 6315 RFC 7566
- Ephemeral key
A key pair generated for a single use and then discarded. Using one per message means a leaked long-term key does not reveal how that message key was made.
Like I'm five A key you make for one door and throw away right after.
- Ephemeral port
A temporary port number picked for the lifetime of one connection or test, rather than a well-known port fixed in advance.
Like I'm five A temporary mailbox number used just for one conversation.
- Ephemeral state
Configuration or operational data that does not persist across a reboot or power cycle. A system cannot roll back to a previous ephemeral configuration state.
Like I'm five Instructions written in pencil that vanish when the device restarts.
- Epoch
A generation or version of the group's shared secret. Each time someone joins or leaves, the group advances to a new epoch with a different secret.
Like I'm five A version number for the group secret. When someone joins or leaves, we make a new version.
- Equal-Cost Multipath
Routing that spreads traffic over several paths that have the same cost. It means a destination can have more than one primary next hop.
Like I'm five Using several equally good roads at once to share the traffic.
Used in RFC 6413 RFC 6790 RFC 7424 RFC 7497 RFC 7510 RFC 7916 RFC 8012 RFC 8086 RFC 8279 RFC 8926 RFC 8986 RFC 9098
- Equal-Cost Multipath
Sharing traffic over several paths that are equally good, so that different packets between the same two points may take different routes.
Like I'm five Using several equally good roads so cars do not all pile onto one.
Used in RFC 2991 RFC 4379 RFC 4385 RFC 4814 RFC 4928 RFC 6374 RFC 6391 RFC 6438 RFC 6576 RFC 7455 RFC 7938 RFC 8395 RFC 8469 RFC 8611 RFC 8662 RFC 9197 RFC 9198 RFC 9403 RFC 9545 RFC 9764 RFC 9815
- Erasure Code
A code that turns k source symbols into n encoding symbols so that the original can be recovered even if some symbols are lost and the positions of the lost ones are known.
Like I'm five A recipe for making extra pieces so the whole thing can be rebuilt when some pieces go missing.
- Escape sequence
A special short sequence of bytes that signals a change in how the bytes following it should be interpreted. In ISO-2022-JP, escape sequences switch between ASCII and Japanese character sets.
Like I'm five A special code that tells the decoder 'start reading Japanese now' or 'back to English.'
- ESP
Encapsulating Security Payload. The IPsec protocol that encrypts and authenticates packets. It is one of the two kinds of Child SA IKE sets up.
Like I'm five The locked envelope that carries your data.
Used in RFC 1829 RFC 1851 RFC 2207 RFC 2356 RFC 2401 RFC 2402 RFC 2403 RFC 2404 RFC 2405 RFC 2406 RFC 2410 RFC 2451 RFC 2473 RFC 2522 RFC 2719 RFC 2857 RFC 2868 RFC 2890 RFC 2894 RFC 3015 RFC 3095 RFC 3193 RFC 3293 RFC 3525 and 101 more
- ETag
A response header field holding an opaque validator for one version of a resource. Clients send it back in If-Match or If-None-Match to make a request conditional on the resource still being that version.
Like I'm five A version sticker. If the sticker changed, the thing changed.
Used in RFC 2068 RFC 2227 RFC 2295 RFC 2617 RFC 3229 RFC 3903 RFC 4791 RFC 4825 RFC 4918 RFC 5023 RFC 5264 RFC 5789 RFC 5839 RFC 5874 RFC 5875 RFC 5989 RFC 6249 RFC 6352 RFC 6578 RFC 6638 RFC 7231 RFC 7232 RFC 7252 RFC 7641 and 16 more
- Ethernet
A family of wired local-area network technologies. A frame carries a destination and source MAC address, an EtherType and the payload.
Like I'm five The wiring and rules that let computers in one building pass messages to each other.
Used in RFC 820 RFC 824 RFC 826 RFC 828 RFC 891 RFC 893 RFC 894 RFC 895 RFC 899 RFC 948 RFC 985 RFC 1027 RFC 1029 RFC 1042 RFC 1054 RFC 1089 RFC 1112 RFC 1122 RFC 1180 RFC 1220 RFC 1284 RFC 1340 RFC 1368 RFC 1369 and 150 more
- Ethernet frame
The unit of data on an Ethernet: a destination address, a source address, a type field and a data field. RFC 894 puts one IP datagram in the data field and sets the type to 0x0800.
Like I'm five The envelope that carries one message across the wire.
Used in RFC 894 RFC 895 RFC 1516 RFC 1638 RFC 2020 RFC 2464 RFC 2516 RFC 2544 RFC 2665 RFC 2895 RFC 3252 RFC 3518 RFC 3635 RFC 4188 RFC 4448 RFC 4719 RFC 4720 RFC 4762 RFC 4789 RFC 4878 RFC 5163 RFC 5180 RFC 5332 RFC 5342 and 30 more
- Ethernet Segment
The set of links that connects one customer site to one or more provider edge devices in EVPN, identified by an Ethernet Segment Identifier.
Like I'm five The group of cables that connects one customer to the network.
Used in RFC 7432 RFC 8365 RFC 9251 RFC 9291 RFC 9784 RFC 9785 RFC 9786
- Ethernet VPN (EVPN)
A way to carry Layer 2 Ethernet services across an IP/MPLS network, using BGP to distribute the MAC and service information that provider edges need.
Like I'm five A way to make faraway Ethernet networks act like one big local network.
- EtherType
A 16-bit field in an Ethernet frame that says which protocol is carried inside. IPv4 uses 0x0800, ARP uses 0x0806 and RARP uses 0x8035.
Like I'm five A label on the envelope that tells the receiver which kind of letter is inside.
Used in RFC 826 RFC 894 RFC 903 RFC 1188 RFC 1209 RFC 1294 RFC 1483 RFC 1700 RFC 1701 RFC 2067 RFC 2427 RFC 2464 RFC 2470 RFC 2516 RFC 2684 RFC 2734 RFC 2784 RFC 2834 RFC 2835 RFC 3032 RFC 3293 RFC 4023 RFC 4326 RFC 4392 and 25 more
- EUI-64
A 64-bit Extended Unique Identifier specified by the IEEE for various layer-2 networks and IPv6 interface identifiers.
Like I'm five A 64-bit address, similar to EUI-48 but twice as large.
Used in RFC 2374 RFC 2464 RFC 2467 RFC 3146 RFC 5342 RFC 6775 RFC 7043 RFC 9039
- Event notification
A message that reports that an event has occurred, sent to whoever subscribed to it. It can be pushed to the recipient or held until the recipient fetches it.
Like I'm five The message that says 'the thing you asked about just happened'.
- Event package
A specification that fills in the details of the SIP event framework for one kind of event, such as its name, bodies and subscription duration.
Like I'm five A rulebook for one kind of update service.
Used in RFC 3265 RFC 3842 RFC 3856 RFC 4235 RFC 4575 RFC 4730 RFC 5875 RFC 5989 RFC 6665
- Event stream
A named, continuously updating and chronologically ordered set of events on a publisher that receivers can subscribe to.
Like I'm five Like a TV channel that shows news as it happens.
- Event-Condition-Action (ECA)
A policy model where an event triggers evaluation of a condition, and if the condition is true, an action is executed. Example: Event = packet arrives, Condition = destination port is 445, Action = drop.
Like I'm five When something happens, check a rule, and if the rule matches, do something about it.
- Evidence record
A structure defined by the Evidence Record Syntax that supports non-repudiation of the existence of data. It is kept up to date over time by re-protecting the data with newer keys and stronger algorithms.
Like I'm five A long-lived receipt that proves something existed at a certain time, and gets renewed so it stays believable.
- EVPN
Ethernet Virtual Private Network, a BGP-based way to carry Ethernet services across a provider network, defined in RFC 7432.
Like I'm five A way for a phone company to carry your local network's traffic across the city using shared roads.
Used in RFC 7623 RFC 8388 RFC 9047 RFC 9135 RFC 9136 RFC 9161 RFC 9251 RFC 9291 RFC 9572 RFC 9574 RFC 9624 RFC 9744 RFC 9784 RFC 9785 RFC 9856
- Exactly once semantics
A guarantee that a request is executed one time even if the client retries it. NFSv4.1 provides it through sessions, slots, sequence IDs and a reply cache.
Like I'm five Even if you ask twice, the job is done only once.
- Exchange hash
The hash H computed over both identification strings, both KEXINIT messages, the host key and the exchanged Diffie-Hellman values. The server signs it with its host key, and the first H of a connection also becomes the session identifier.
Like I'm five A fingerprint of the whole conversation that the server signs to prove it took part.
Used in RFC 4253 RFC 4419 RFC 4432 RFC 4462 RFC 5656 RFC 8268 RFC 8731 RFC 8732 RFC 9037 RFC 9142
- Expert Review
An IANA registration procedure in which a designated expert checks a request against stated criteria before it is accepted.
Like I'm five A helper checks your form before it goes on the official list.
Used in RFC 3936 RFC 4520 RFC 5494 RFC 9122 RFC 9519 RFC 9876
- Explicit Address Mapping
A two-way pairing between an IPv4 address and an IPv6 address configured in a translator, used instead of the translation prefix for matching addresses.
Like I'm five A list that says which old address goes with which new address.
- Explicit Congestion Notification
A mechanism for network devices to signal congestion to endpoints by marking packets instead of dropping them, using a 2-bit field in IP headers.
Like I'm five Routers mark packets instead of throwing them away to tell senders the network is busy.
- Explicit Congestion Notification
Two bits in the IP header that routers can use to signal congestion to endpoints without having to drop packets.
Like I'm five A little flag routers raise to say the road is getting busy.
Used in RFC 2914 RFC 3168 RFC 3360 RFC 3540 RFC 4340 RFC 4341 RFC 4774 RFC 5129 RFC 6040 RFC 6660 RFC 6679 RFC 7141 RFC 7560 RFC 7713 RFC 7750 RFC 8311 RFC 8888 RFC 9330 RFC 9331 RFC 9332 RFC 9599 RFC 9600 RFC 9601 RFC 9743 and 2 more
- Explicit Route
A path given as an ordered list of hops that signaling must follow, instead of leaving the choice to dynamic routing. Hops can be strict or loose.
Like I'm five A list of exact stops to visit in order, instead of letting the driver pick the road.
- Explicit Route Object
An RSVP object carried in a Path message that lists the hops an LSP should take. Each hop can be strict or loose.
Like I'm five A list of stops that says which way the trip should go.
Used in RFC 3477 RFC 4208 RFC 5063 RFC 5151 RFC 7570 RFC 7898
- Exponential backoff
Doubling a timer's value each time it expires without success, so repeated retries become less frequent. TCP does this to its retransmission timeout.
Like I'm five Each time nobody answers, you wait twice as long before trying again.
Used in RFC 1536 RFC 2730 RFC 4222 RFC 6298 RFC 7048 RFC 7252 RFC 7559
- Extended Community
A BGP attribute that attaches additional tags to routes. In RFC 4360 each such community is 8 octets long, with a type and a sub-type.
Like I'm five A small label that a router sticks on a route to say something extra about it.
- Extended Key Usage
An X.509 certificate extension that specifies the purposes for which the certificate may be used, such as TLS server authentication or code signing.
Like I'm five A label on a certificate that says what you can use it for.
Used in RFC 3770 RFC 4556 RFC 5924 RFC 6494 RFC 9336 RFC 9480 RFC 9509 RFC 9809
- Extended Operation
An LDAPv3 mechanism for adding new request and response types, each identified by an object identifier. Password Modify is defined this way.
Like I'm five A way to add a brand new kind of request to a protocol without changing the protocol itself.
- Extended Sequence Number
An Extended Sequence Number (ESN) is a 64-bit packet counter for an IPsec SA. Only the low-order 32 bits are sent in each packet, while both sides track the high-order bits locally.
Like I'm five A very long ticket number that mostly stays hidden.
- Extensible Provisioning Protocol
An XML-based client-server protocol for provisioning and managing objects in a shared central repository, such as a domain registry.
Like I'm five A standard language that registrars use to communicate with domain registries.
Used in RFC 3732 RFC 3733 RFC 3915 RFC 4114 RFC 4930 RFC 4931 RFC 4932 RFC 5076 RFC 5734 RFC 7848 RFC 8056 RFC 8334 RFC 8495 RFC 8544 RFC 8807 RFC 9038 RFC 9803 RFC 9873
- Extensible Provisioning Protocol
An XML-based protocol that clients use to create and manage objects such as domain names in a shared central repository. Extensions add new kinds of data to its commands.
Like I'm five A standard set of forms that lets a registrar manage names stored at a registry.
- Extension header
An optional IPv6 header placed between the IPv6 header and the upper-layer header, found by following Next Header fields. Examples are Hop-by-Hop Options, Routing, Fragment and Destination Options.
Like I'm five A sticker with extra instructions on the packet.
Used in RFC 1710 RFC 1752 RFC 1883 RFC 1888 RFC 2292 RFC 2460 RFC 2473 RFC 2675 RFC 3025 RFC 3149 RFC 3542 RFC 4064 RFC 4294 RFC 4552 RFC 4815 RFC 4917 RFC 4942 RFC 4964 RFC 5002 RFC 5094 RFC 5095 RFC 5096 RFC 5163 RFC 5180 and 50 more
- Exterior Gateway Protocol
A protocol for exchanging network reachability information between autonomous systems (networks). EGP allows one network to learn what other networks another system can reach.
Like I'm five A way for one big network to tell another big network what addresses it can deliver to.