Glossary
M
132 terms.
- MAC address
A hardware address assigned to a network interface. Ethernet MAC addresses are 48 bits long and are usually written as six hexadecimal bytes, such as 08:00:20:01:AB:C2.
Like I'm five A name tag built into your network card that no other card has.
Used in RFC 826 RFC 894 RFC 895 RFC 903 RFC 925 RFC 951 RFC 982 RFC 1103 RFC 1112 RFC 1188 RFC 1229 RFC 1231 RFC 1284 RFC 1286 RFC 1329 RFC 1390 RFC 1434 RFC 1469 RFC 1493 RFC 1512 RFC 1513 RFC 1516 RFC 1541 RFC 1542 and 193 more
- MAC-VRF
A virtual routing and forwarding table for MAC addresses on a provider edge router. Each EVPN instance has one on each router that takes part.
Like I'm five A separate address book a router keeps for each customer network.
- Macroblock
A 16-by-16 pixel region in a video frame that is encoded and transmitted as a unit in H.261 compression.
Like I'm five A small square of pixels (16 by 16) in a video that is squeezed and sent together.
Used in RFC 2032 RFC 2429 RFC 6386 RFC 7741 RFC 7867 RFC 9924
A fixed four-byte value, 99.130.83.99 (hex 63.82.53.63), placed at the start of the BOOTP vendor field to show that what follows is a list of tagged options. DHCP options use the same marker.
Like I'm five A secret handshake at the start of a note that says "the labelled list begins here".
Used in RFC 1497 RFC 1533 RFC 1542 RFC 2131 RFC 2132 RFC 2637 RFC 5389 RFC 8489
- Magic-Number
A random 32-bit number each PPP end picks and sends in an LCP option. If a peer receives its own number back, the link is probably looped back to itself.
Like I'm five A secret random ticket you hand out; if you get your own ticket back, you are talking to a mirror.
Used in RFC 1331 RFC 1471 RFC 1548 RFC 1570 RFC 1661 RFC 1663 RFC 1989 RFC 2153 RFC 2363 RFC 2364 RFC 2854 RFC 3284 RFC 3302 RFC 3772 RFC 6994 RFC 7527 RFC 8118 RFC 9277
- Mail envelope
The sender and recipient addresses given to SMTP in the MAIL FROM and RCPT TO commands. They are used for delivery and are separate from the From and To lines inside the message.
Like I'm five The writing on the outside of the envelope, which the mail carrier reads, not the letter inside.
Used in RFC 479 RFC 621 RFC 806 RFC 821 RFC 822 RFC 841 RFC 886 RFC 976 RFC 1148 RFC 1203 RFC 1486 RFC 1495 RFC 1528 RFC 1651 RFC 1711 RFC 1869 RFC 1894 RFC 2033 RFC 2156 RFC 2162 RFC 2476 RFC 2821 RFC 2822 RFC 3028 and 34 more
- Mail relay
A host that receives mail not meant for itself and passes it on toward its destination, which is how SMTP can carry mail across different networks.
Like I'm five A friend in the middle who takes your note and carries it to the next town.
Used in RFC 754 RFC 763 RFC 780 RFC 785 RFC 786 RFC 788 RFC 799 RFC 805 RFC 821 RFC 897 RFC 915 RFC 921 RFC 974 RFC 987 RFC 993 RFC 1204 RFC 1211 RFC 1460 RFC 1506 RFC 1649 RFC 1651 RFC 1711 RFC 1838 RFC 1846 and 25 more
- Mailbox
In RFC 5322, a destination for mail, written as an address like
user@example.comor with a display name,John Doe <john@example.com>.Like I'm five One person's mail slot, with or without their name next to it.
Used in RFC 196 RFC 278 RFC 303 RFC 458 RFC 469 RFC 475 RFC 491 RFC 510 RFC 524 RFC 539 RFC 543 RFC 555 RFC 621 RFC 630 RFC 680 RFC 720 RFC 744 RFC 751 RFC 754 RFC 757 RFC 759 RFC 763 RFC 767 RFC 780 and 141 more
- Maildrop
The place on a server where a user's incoming mail is held until the client collects it. In POP3 the server locks the maildrop for the whole session.
Like I'm five Your own mailbox at the post office.
Used in RFC 1081 RFC 1082 RFC 1225 RFC 1339 RFC 1460 RFC 1725 RFC 1939 RFC 2449 RFC 6856
- Mailing List
A named group of recipients who share a common address, allowing a single message to be delivered to multiple people.
Like I'm five One address that sends to many people.
- Maintenance Entity
In MPLS-TP, a management unit consisting of endpoints (MEPs) that bound the OAM scope for monitoring and managing a transport path or segment.
Like I'm five A section of the network that you monitor and manage as one unit.
- Maintenance Entity Group
A set of Maintenance Entities associated with the same service instance, used to organize OAM monitoring across multiple managed points.
Like I'm five A group of monitors all watching the same network service.
- Maintenance Entity Group End Point
An end point of a monitored path in MPLS-TP OAM, abbreviated MEP. It is where OAM messages about that path are sent and received.
Like I'm five The place at either end of a road where inspectors send and read reports.
- Make-before-break
Setting up a new path and moving traffic onto it before the old path is torn down. This avoids a gap in delivery.
Like I'm five Building the new bridge before closing the old one.
Used in RFC 3209 RFC 4192 RFC 4736 RFC 4872 RFC 4873 RFC 4875 RFC 5557 RFC 5710 RFC 5712 RFC 7010 RFC 7823 RFC 8131 RFC 8149
- Man in the middle
An attack in which someone secretly sits between two parties, relaying and possibly altering their traffic while each believes it is talking directly to the other.
Like I'm five Someone who stands between you and a friend, passing notes back and forth while quietly reading or changing them.
Used in RFC 3329 RFC 3748 RFC 3833 RFC 5801 RFC 6181 RFC 6797 RFC 6876 RFC 7029 RFC 7171 RFC 7201 RFC 7619 RFC 8600 RFC 8633 RFC 8826 RFC 8827 RFC 9048 RFC 9463 RFC 9588 RFC 9891 RFC 9985
- Man-in-the-middle attack
An attack in which someone sits between two parties and pretends to each to be the other, so they can watch or change the traffic. SSH defends against it by checking the server's host key.
Like I'm five Somebody secretly stands between you and your friend, passing notes back and forth and reading them.
Used in RFC 2246 RFC 2371 RFC 2595 RFC 2607 RFC 2617 RFC 2817 RFC 2818 RFC 2829 RFC 2830 RFC 3118 RFC 3157 RFC 3207 RFC 3552 RFC 3631 RFC 3656 RFC 3694 RFC 3756 RFC 3760 RFC 3767 RFC 3788 RFC 3837 RFC 3887 RFC 3892 RFC 3903 and 122 more
- Managed Object
A single item in a MIB, such as a setting or a counter, that a management protocol like SNMP can read and sometimes change.
Like I'm five One dial or counter on a control panel that a manager can look at or turn.
Used in RFC 1156 RFC 1158 RFC 1213 RFC 1441 RFC 2108 RFC 6173
- Management Information Base
A standardized catalog of data objects that network devices expose via SNMP, allowing remote monitoring and configuration.
Like I'm five A list of questions you can ask a device to find out how it is doing.
Used in RFC 1098 RFC 1248 RFC 1441 RFC 1611 RFC 2012 RFC 2837 RFC 5728 RFC 6632
- Management Information Base
A database of managed objects, described in a standard format, that a network device exposes for monitoring and control via SNMP.
Like I'm five A standardized set of measurements and controls that a router exposes so network administrators can see how it is working.
- Mandatory Access Control
An access model in which every subject and object carries a security label, and a system-wide policy decides access from those labels.
Like I'm five A rulebook where everything wears a badge and the badges decide who may touch what.
- Mandatory-to-implement
A feature or algorithm that every compliant implementation must include, so that any two implementations have at least one option in common.
Like I'm five A tool every builder has to include in the toolbox so everyone can work together.
- MANET
A mobile ad hoc network, in which connectivity to some destinations is provided by forwarding through intermediate devices.
Like I'm five A network of moving radios that pass messages along for one another.
Used in RFC 3684 RFC 5497 RFC 5498 RFC 5614 RFC 6130 RFC 6779 RFC 7038 RFC 7181 RFC 7185 RFC 7188 RFC 7367 RFC 7722 RFC 7939 RFC 7985 RFC 8218 RFC 8245 RFC 8629
- Manifest
In the context of XML signatures, a collection of references to the objects being signed, specifying what content the signature covers.
Like I'm five A list of what things are being signed.
- Manufacturer Usage Description
A model, defined in RFC 8520, in which a manufacturer publishes a file describing a device, which can include the network access it needs. RFC 9472 extends it.
Like I'm five A data sheet from the maker that tells the network what a gadget is and how it should behave.
- Manufacturer Usage Description (MUD)
A file published by a device maker that describes which network resources the device needs to reach. A network can use it to build access control rules for that device.
Like I'm five A list from the toy maker saying which places the toy is allowed to talk to.
- Map-Cache
The local store where an ITR keeps EID-to-RLOC mappings it has learned from Map-Replies. Each entry is kept for the time given in the record's TTL.
Like I'm five A little notebook where you jot down answers you got so you need not ask again.
- MAPOS
Multiple Access Protocol over SONET/SDH, a link-layer protocol that lets several nodes share SONET/SDH links through a Frame Switch.
Like I'm five A way for many computers to share one fast fiber line.
- Marker bit
A single bit in the RTP header whose meaning depends on the payload format. For DV video it is set on the last packet of a frame.
Like I'm five A flag on the last envelope that says this is the end of the picture.
- MARS
The Multicast Address Resolution Server, a server that distributes multicast group membership information to endpoints on an ATM network. Its clients are grouped into a cluster.
Like I'm five The keeper of the club register who knows which members belong to which club.
- Masking
Every client-to-server frame has its payload XORed with a 32-bit masking key that travels in the frame header. It is meant to stop a client from being used to craft traffic that could confuse intermediaries.
Like I'm five Scrambling the message a little on its way out so nobody can trick the network.
- Master agent
The SNMP agent that talks to managers and passes requests on to AgentX subagents, which implement parts of the MIB it has registered for them.
Like I'm five The front-desk person who takes your question and passes it to the right helper.
- Master file
A text file listing the resource records of one zone, edited by the zone's administrator and loaded by a name server as authoritative data.
Like I'm five The original page in the big phone book, written by the person in charge of it.
- Master key
A random secret handed to SRTP by key management. All session keys for encryption, authentication and salting are derived from it.
Like I'm five One big secret that the smaller secrets are made from.
Used in RFC 2246 RFC 3118 RFC 3711 RFC 3748 RFC 4186 RFC 4187 RFC 4346 RFC 4563 RFC 4568 RFC 5091 RFC 5191 RFC 5247 RFC 5295 RFC 5408 RFC 5433 RFC 5448 RFC 5705 RFC 5794 RFC 5926 RFC 6188 RFC 6358 RFC 6678 RFC 6696 RFC 6734 and 8 more
- Master Session Key (MSK)
Key material exported by an EAP method after a successful authentication. Other keys, such as those for a security association, are derived from it.
Like I'm five The first secret both sides learn after proving who they are, used to make more secrets.
- Matching rule
A rule that tells an LDAP server how to compare two values, for example for equality or for ordering. Each attribute type names the rules that apply to it.
Like I'm five The rule for deciding whether two things count as the same, or which one comes first.
- Maturity level
The standardization state of a protocol, indicating whether it is a standard, draft standard, proposed standard, experimental, informational, or historic.
Like I'm five How official or tested a protocol is.
- Maximally Redundant Trees
A pair of spanning trees rooted at the same node that give every other node two paths to the root sharing the fewest possible nodes and links. They are named MRT-Blue and MRT-Red.
Like I'm five Two routes to the same place that overlap as little as they possibly can.
- Maximum Segment Size (MSS)
A TCP option, sent in a SYN, that tells the peer the largest segment payload the sender is willing to receive. Without it, 536 bytes is assumed for IPv4 and 1220 for IPv6.
Like I'm five The biggest envelope your friend can open.
Used in RFC 793 RFC 879 RFC 1191 RFC 1201 RFC 1981 RFC 2140 RFC 2147 RFC 2385 RFC 2414 RFC 2581 RFC 2675 RFC 2923 RFC 3081 RFC 3150 RFC 3390 RFC 4404 RFC 4413 RFC 4614 RFC 5681 RFC 6691 RFC 6817 RFC 6928 RFC 7413 RFC 7805 and 9 more
- Maximum SID Depth (MSD)
The largest number of segment identifiers (SIDs) that a node or link can handle when imposing a SID stack on a packet.
Like I'm five How many labels a router can stick on one packet.
- maxLength
An optional ROA attribute giving the longest prefix length the AS is authorized to advertise. It lets one entry stand for many more-specific prefixes.
Like I'm five A shortcut on the permission note that also allows many smaller pieces of the address block.
- MD5 hash
A one-way function that turns any input into a 16-byte fingerprint. RADIUS uses it to hide passwords and to sign replies, though MD5 is no longer considered strong.
Like I'm five A blender for data: the same ingredients always give the same smoothie, but you cannot un-blend it.
Used in RFC 1186 RFC 1321 RFC 1352 RFC 1423 RFC 1460 RFC 1724 RFC 1725 RFC 1751 RFC 1760 RFC 1810 RFC 1828 RFC 1852 RFC 1864 RFC 1890 RFC 1910 RFC 1964 RFC 1994 RFC 2002 RFC 2058 RFC 2069 RFC 2082 RFC 2085 RFC 2104 RFC 2107 and 106 more
- mDNS
Multicast DNS, defined in RFC 6762. Hosts on a local link send DNS-format queries to a multicast address and the host that owns the name answers, so names can be resolved with no DNS server.
Like I'm five Calling a name out loud in the room instead of looking it up in a phone book.
Used in RFC 4795 RFC 5687 RFC 6055 RFC 6641 RFC 6760 RFC 6762 RFC 6763 RFC 6804 RFC 7368 RFC 7558 RFC 7605 RFC 7788 RFC 8117 RFC 8155 RFC 8222 RFC 8764 RFC 8766 RFC 8882 RFC 9665 RFC 9726
- Measurement Agent
In an LMAP platform, the element that actually performs measurements. It follows instructions from exactly one Controller at a time and reports results to one or more Collectors.
Like I'm five A little gadget that runs tests and tells the boss what it found.
The process of verifying that a requested multimedia stream (audio, video, data) is authorized by policy before network resources are reserved to deliver it.
Like I'm five Checking that someone is allowed to use certain bandwidth and quality before letting them have it.
- Media Capture
A source of media (video, audio, or timed text) that a Media Provider can encode and send, such as a camera, microphone, screen, or mixed content from multiple sources.
Like I'm five A camera, microphone, screen, or other source of media that can be shared.
- Media clipping
Loss of the first part of a media stream because packets arrive before the receiver is able to process them.
Like I'm five The first words of a call get cut off because the listener was not ready yet.
- Media feature tag
A named label that describes a capability of a device, such as supporting ICE. In SIP such tags can be carried in the Contact header field.
Like I'm five A little label on a device that says what it can do.
- Media Gateway
A network device that converts media (usually voice) between telephone networks and IP networks, controlled by a call agent via MGCP commands.
Like I'm five A box that connects a telephone network to the internet and lets a central computer tell it what to do.
Used in RFC 2705 RFC 2805 RFC 2885 RFC 3015 RFC 3435 RFC 3441 RFC 3525 RFC 3660 RFC 5347
- Media Gateway Controller
The node that performs call processing for signaling that a gateway has backhauled to it. In IUA it is the MGC, where the Q.931 layer runs.
Like I'm five The brain that decides what to do with each call the gateway passes along.
Used in RFC 2719 RFC 2885 RFC 3015 RFC 3398 RFC 3525 RFC 4233
- Media Server
A server that performs media services such as playing audio, mixing streams or running interactive voice response, under the control of an Application Server.
Like I'm five A helper machine that does the audio and video jobs for another program.
Used in RFC 4240 RFC 4722 RFC 5022 RFC 5567 RFC 5616 RFC 5707 RFC 6231 RFC 6505 RFC 6917
- Media type (MIME type)
A label of the form
type/subtype, such astext/plainorimage/jpeg, carried in the Content-Type header. The type gives the general kind of data and the subtype the specific format.Like I'm five A two-word sticker on a box. The first word says the kind of thing, the second says exactly which one.
Used in RFC 767 RFC 910 RFC 1341 RFC 1524 RFC 1590 RFC 1766 RFC 1767 RFC 1895 RFC 1896 RFC 2017 RFC 2045 RFC 2046 RFC 2048 RFC 2049 RFC 2077 RFC 2122 RFC 2158 RFC 2160 RFC 2220 RFC 2295 RFC 2296 RFC 2298 RFC 2318 RFC 2361 and 291 more
- Media-Aware Network Element
A middlebox or gateway that can parse parts of the RTP payload and react to what it finds. For example, it can drop the least important packets when a link is congested.
Like I'm five A smart mail sorter in the middle that can read the labels and decide what to throw away first when the truck is full.
- Medium Attachment Unit (MAU)
The part of an IEEE 802.3 Ethernet port that connects a device or repeater to the physical medium, such as copper or fiber. A MAU type fixes the speed, cabling and duplex mode.
Like I'm five The part that plugs a device into the Ethernet cable.
- Memory-hard function
A function that needs a large amount of memory as well as time to compute, so that building faster hardware gives an attacker less of an advantage.
Like I'm five A puzzle that needs a big table to solve, not just a fast brain.
- Merge Point
The router where a backup path rejoins the primary path. There can be several Merge Points for a single protected node.
Like I'm five The spot where the detour road joins the main road again.
Used in RFC 4090 RFC 4561 RFC 7431 RFC 7715 RFC 8271 RFC 8796 RFC 9705
- Merkle tree
A binary tree in which each interior node holds the hash of its two children. The value at the root commits to everything at the leaves.
Like I'm five A family tree of fingerprints where the top fingerprint depends on every fingerprint below it.
Used in RFC 4998 RFC 6962 RFC 8391 RFC 8554 RFC 8708 RFC 9162 RFC 9708 RFC 9802 RFC 9942 RFC 10033 RFC 10049
- Mesh Network
A network where devices relay messages for each other through multiple hops, allowing communication to continue even if direct links are blocked or fail.
Like I'm five A network where each device can pass messages along to its neighbors, so a message can reach far-away devices by hopping from one neighbor to the next.
- Message authentication code
A short, fixed-length value computed from a message and a secret key. The receiver recomputes it to check that the message has not been altered.
Like I'm five A secret stamp that shows nobody changed the message.
Used in RFC 2845 RFC 3566 RFC 3652 RFC 4082 RFC 4442 RFC 5830 RFC 6476 RFC 7165 RFC 7539 RFC 8152
- Message authentication code (MAC)
A short value computed from a message and a shared secret that lets the receiver detect any change to the message. SSH includes a packet sequence number in the MAC input to prevent replay.
Like I'm five A secret seal on each letter that breaks if anyone changes the letter.
Used in RFC 2104 RFC 2403 RFC 2410 RFC 2743 RFC 2841 RFC 3394 RFC 3566 RFC 3610 RFC 4225 RFC 4251 RFC 4253 RFC 4344 RFC 4383 RFC 4418 RFC 4493 RFC 4758 RFC 4771 RFC 5083 RFC 5282 RFC 5487 RFC 5926 RFC 6010 RFC 6584 RFC 6622 and 25 more
- Message digest
A short fixed-size value computed from data with a hash function. Changing the data, even slightly, changes the digest, so it works as a fingerprint of the content.
Like I'm five A fingerprint made from a message; change one letter and the fingerprint is different.
Used in RFC 1036 RFC 1115 RFC 1153 RFC 1186 RFC 1319 RFC 1320 RFC 1321 RFC 1352 RFC 1423 RFC 1446 RFC 1704 RFC 1847 RFC 1864 RFC 2095 RFC 2104 RFC 2154 RFC 2202 RFC 2311 RFC 2315 RFC 2404 RFC 2437 RFC 2574 RFC 2630 RFC 2634 and 89 more
- Message disposition notification
A message generated on the recipient side that reports what happened to a mail message, for example that it was refused or deleted. It is usually abbreviated MDN.
Like I'm five A note back to the sender saying what happened to their letter.
Used in RFC 2532 RFC 3335 RFC 3798 RFC 4130 RFC 5429 RFC 6533 RFC 9007
- Message framing
The rules that tell a receiver where one message ends and the next begins. In HTTP/1.1 they are Content-Length, chunked coding, or closing the connection.
Like I'm five The way you know where one sentence stops and the next starts.
Used in RFC 58 RFC 618 RFC 1055 RFC 1153 RFC 1154 RFC 1547 RFC 1618 RFC 1625 RFC 1662 RFC 2126 RFC 3080 RFC 3257 RFC 3286 RFC 4037 RFC 4571 RFC 4582 RFC 4767 RFC 4824 RFC 4975 RFC 5044 RFC 5045 RFC 5425 RFC 5460 RFC 5734 and 15 more
- Message Integrity Check
A code computed from a message that allows the recipient to verify that the message has not been altered in transit.
Like I'm five A check number that proves nobody changed the message.
- Message integrity code (MIC)
A value computed over a message so the receiver can check it was not altered. In GSS it is produced by the GetMIC operation.
Like I'm five A seal on a letter that breaks if someone changes what is inside.
- Message Processing Model
A set of version-specific procedures for building and taking apart SNMP messages and for asking a security model to protect them. Several models can exist at the same time.
Like I'm five A rulebook for one kind of envelope, saying how to pack and unpack it.
- Message sequence number
The position of a message in an IMAP mailbox, counted from the start. It can shift when earlier messages are expunged.
Like I'm five Where an email stands in line, which changes when someone ahead leaves.
- Message Submission Agent (MSA)
The server process that accepts new messages from mail programs, normally on port 587, checks that the sender is authorized, and either delivers the message or relays it onward as an SMTP client.
Like I'm five The mail clerk at your own post office who checks your ID and your address before sending your letter on.
Used in RFC 2476 RFC 4409 RFC 4468 RFC 4865 RFC 4871 RFC 5068 RFC 5598 RFC 6186 RFC 6409 RFC 6710 RFC 7960 RFC 8314 RFC 8617 RFC 9422
- Message Transfer Agent (MTA)
A mail server that speaks SMTP to accept messages from an MSA or another MTA and then delivers them or relays them to the next MTA. MTAs are not supposed to alter message text beyond adding trace headers.
Like I'm five A post office that passes letters along to the next post office without opening them.
Used in RFC 821 RFC 841 RFC 934 RFC 987 RFC 989 RFC 1137 RFC 1138 RFC 1210 RFC 1327 RFC 1421 RFC 1616 RFC 1649 RFC 1653 RFC 1711 RFC 1801 RFC 1847 RFC 1891 RFC 1894 RFC 2015 RFC 2049 RFC 2156 RFC 2249 RFC 2369 RFC 2476 and 69 more
- Message User Agent (MUA)
The program that composes and submits new messages and shows delivered ones, often with a user interface. A mail app on a phone or computer is an MUA.
Like I'm five The mail app you type your emails in.
Used in RFC 934 RFC 1343 RFC 1421 RFC 1524 RFC 2156 RFC 2183 RFC 2369 RFC 2476 RFC 2505 RFC 2524 RFC 2532 RFC 2542 RFC 2919 RFC 3249 RFC 3458 RFC 3464 RFC 3503 RFC 3798 RFC 3865 RFC 4409 RFC 4865 RFC 4871 RFC 4952 RFC 5068 and 23 more
- Message-ID
A header field holding a globally unique identifier for one message, written in angle brackets. Replies cite it in
In-Reply-ToandReferencesso clients can build conversations.Like I'm five A serial number no other email in the world has.
Used in RFC 533 RFC 534 RFC 680 RFC 806 RFC 807 RFC 808 RFC 809 RFC 841 RFC 850 RFC 977 RFC 987 RFC 1036 RFC 1138 RFC 1820 RFC 1872 RFC 2059 RFC 2076 RFC 2111 RFC 2262 RFC 2359 RFC 2392 RFC 2557 RFC 2822 RFC 3249 and 24 more
- Metadata
Data about data; information that describes properties of a resource such as its name, type, location, size and modification status.
Like I'm five Information that describes what something is.
Used in RFC 1728 RFC 5013 RFC 5812 RFC 8153 RFC 8165 RFC 9065
- MetaData Server (MDS)
The NFSv4 server in a pNFS system. It provides pNFS layouts to clients and handles operations on file metadata such as names and attributes.
Like I'm five The helper who knows where everything is kept and tells you which shelf to use.
- MIB
The Management Information Base. A standard collection of named values, such as counters and tables, that a management protocol can read or set on a managed host or gateway.
Like I'm five A checklist of dials and gauges that a machine shows to its administrator.
Used in RFC 1023 RFC 1052 RFC 1065 RFC 1066 RFC 1067 RFC 1076 RFC 1095 RFC 1109 RFC 1123 RFC 1155 RFC 1156 RFC 1157 RFC 1158 RFC 1162 RFC 1189 RFC 1208 RFC 1212 RFC 1213 RFC 1214 RFC 1215 RFC 1227 RFC 1229 RFC 1230 RFC 1231 and 541 more
- MIB Module
A formal description of managed objects (settings, counters, and status values) that a network device exposes to SNMP. Defined using the Structure of Management Information (SMI).
Like I'm five A blueprint that lists all the switches, dials, and counters on a network device that SNMP can read or change.
- MIB view
A named subset of the managed objects in an SNMP context, built from included and excluded subtrees. Access control grants a group rights in terms of such views.
Like I'm five A list of which shelves in the library a person is allowed to look at.
Used in RFC 1351 RFC 1909 RFC 2265 RFC 2275 RFC 2575 RFC 3415
- MIBenum
A unique enumerated integer value assigned by IANA to each registered charset. The values are defined by and used in the Printer MIB.
Like I'm five A number the list keeper gives each code so it can be told apart from all the others.
- Micro session
A measurement session set up on a single member link of a LAG, so that each link gets its own performance numbers. All micro sessions of a LAG share the same sender and receiver IP addresses.
Like I'm five A separate speed test for each lane of a road.
- Micro-loop
A short-lived forwarding loop that appears while routers update their forwarding tables at different times after a topology change.
Like I'm five Two routers briefly pass a packet back and forth because they have not both heard the news yet.
Used in RFC 5286 RFC 5714 RFC 5715 RFC 6413 RFC 6571 RFC 8333 RFC 8405
- Middlebox
A device on the path such as a firewall, load balancer or proxy that handles traffic without being the endpoint.
Like I'm five A guard standing in the hallway between you and who you are talking to.
Used in RFC 3168 RFC 3234 RFC 3238 RFC 3303 RFC 3304 RFC 3323 RFC 3360 RFC 3424 RFC 3540 RFC 3724 RFC 3752 RFC 3835 RFC 3917 RFC 3989 RFC 4037 RFC 4080 RFC 4097 RFC 4236 RFC 4340 RFC 4540 RFC 4571 RFC 4924 RFC 4942 RFC 5045 and 115 more
- MIDI
Musical Instrument Digital Interface, a standard protocol for digital communication between musical instruments, synthesizers, and computers.
Like I'm five A standard language that music instruments and computers use to talk to each other.
- MIKEY
Multimedia Internet KEYing, a key management protocol that sets up session keys for real-time multimedia in a single round trip. It is defined in RFC 3830.
Like I'm five A quick way for two callers to agree on a secret key before they start talking.
- MIME
Multipurpose Internet Mail Extensions. A set of standards (RFC 2045 to RFC 2049) that let Internet mail carry non-ASCII text, attachments, images and nested messages by adding headers that describe the body.
Like I'm five A system of labels and packing rules that lets a plain-text mail service carry pictures, sounds and files.
Used in RFC 821 RFC 850 RFC 1040 RFC 1341 RFC 1342 RFC 1344 RFC 1399 RFC 1426 RFC 1427 RFC 1428 RFC 1437 RFC 1456 RFC 1477 RFC 1486 RFC 1489 RFC 1494 RFC 1495 RFC 1496 RFC 1505 RFC 1521 RFC 1522 RFC 1523 RFC 1524 RFC 1528 and 279 more
- MIME content type
A label that describes what kind of data is in a message body, such as text/plain or image/jpeg, allowing mail readers to know how to handle it.
Like I'm five A label that tells your email program what kind of information is in a message, like plain text or a picture.
- MIME Media Type
A label that identifies the type of content in a file or message, so programs know how to handle it. Consists of a type and subtype (e.g., text/plain, image/jpeg, application/cms).
Like I'm five A label that tells your computer what kind of file it is and what program should open it.
- MIME media type
A label such as text/calendar that tells a program what kind of data a body part holds, so it can pass it to the right application.
Like I'm five The sticker on the envelope that says what is inside.
Used in RFC 807 RFC 809 RFC 850 RFC 1049 RFC 1343 RFC 1494 RFC 1495 RFC 1521 RFC 1563 RFC 1740 RFC 1842 RFC 1844 RFC 1847 RFC 1872 RFC 1873 RFC 1874 RFC 1892 RFC 1894 RFC 2044 RFC 2077 RFC 2110 RFC 2112 RFC 2159 RFC 2183 and 159 more
- Mix-up attack
An attack on an OAuth client that talks to several authorization servers, where the attacker tricks the client about which server is responding so that it sends an authorization code or access token to the attacker.
Like I'm five Tricking someone into handing a secret to the wrong person by hiding who a message really came from.
- Mixed raster content
A way of splitting a page into a mask layer plus foreground and background layers, so that each part can use the compression method and resolution that suit it best.
Like I'm five Splitting a page into see-through layers so text and photos can each be packed their own way.
- Mixing function
A function, such as a hash or a block cipher, that combines several inputs so each output bit depends in a complex way on all input bits. It can hide weak or guessable inputs among good ones, but it cannot make more unpredictability than went in.
Like I'm five A blender that stirs several ingredients together so you cannot tell which one was which.
- MKI
Master Key Identifier. An optional field in an SRTP packet that tells the receiver which master key was used, which makes re-keying easy.
Like I'm five A label saying which key on the ring to use.
- Mobile Access Gateway
In Proxy Mobile IPv6, the entity that detects a mobile node's attachment and provides it with IP connectivity.
Like I'm five The doorway your device walks through to get onto the network.
Used in RFC 4831 RFC 4832 RFC 5844 RFC 5846 RFC 5847 RFC 5949 RFC 6097 RFC 6463 RFC 6572 RFC 6602 RFC 6705 RFC 6757 RFC 6909 RFC 7222 RFC 7389 RFC 7563 RFC 7864 RFC 8191
- Mobile host
A device that moves between network subnets and requires its IP traffic to be redirected as it moves, typically handled by mobility protocols like Mobile IPv4 or Mobile IPv6.
Like I'm five A computer or phone that moves around and changes which network it is connected to.
- Mobile IP
A protocol that lets a mobile device keep its IP address while roaming between different networks, by using tunneling and home agents to redirect traffic.
Like I'm five A way for your device to keep the same phone number no matter which WiFi network it connects to.
- Mobile IPv4
A protocol allowing IPv4 devices to move between networks while maintaining the same IP address and remaining reachable through a Home Agent.
Like I'm five A way for devices to stay connected to the same address even when they travel to different networks.
- Mobile IPv6
A protocol where a mobile node keeps a home address and registers its current location with a home agent, so it stays reachable when it moves away from its home link.
Like I'm five Keeping your old home address for mail even when you move around.
- Mobile Network Prefix
An IPv6 prefix delegated to a Mobile Router and advertised in the Mobile Network. A Mobile Network can have more than one.
Like I'm five The street name shared by every house on the moving street.
- Mobile Node
A device that moves between networks in Mobile IPv4 while maintaining a single home IP address and connectivity.
Like I'm five A traveling device that can roam but stay reachable at its home address.
Used in RFC 2290 RFC 3344 RFC 4004 RFC 4332 RFC 4636 RFC 4640 RFC 5555 RFC 5568 RFC 6610
- Mobile Router
A router inside a moving network (aircraft or spacecraft) that manages connectivity for all devices in that network.
Like I'm five A router that travels with you and keeps all your devices connected.
Used in RFC 3963 RFC 4885 RFC 4886 RFC 4887 RFC 4888 RFC 4889 RFC 4980 RFC 5177 RFC 5522 RFC 6276
- Mobility
The ability of devices to remain connected and functional while moving between networks or changing their point of attachment.
Like I'm five Devices staying connected when they move between WiFi and cellular, or between different areas.
- Mobility Anchor Point
A router in a visited network that acts as a local home agent for mobile nodes. It tracks their current addresses so that movements inside its domain can be handled locally.
Like I'm five A front desk that knows which room you are in and passes your mail on.
- Mobility binding
The association of a mobile node's home address with a care-of address, along with the remaining lifetime of that association.
Like I'm five A note saying "this person is staying at that address until this date".
- MODP group
A fixed, agreed-upon prime number and generator used for Diffie-Hellman arithmetic modulo that prime. Its size in bits largely determines how strong the key exchange is.
Like I'm five A shared set of big numbers that two sides use so they can agree on a secret.
- MPEG-2 Transport Stream
A standard container format used in the transmission and storage of multimedia data. It is widely carried over RTP in IPTV systems.
Like I'm five A package format that bundles video, sound and timing signals into small pieces to send them.
- MPLS
Multiprotocol Label Switching: a technique that forwards packets using short labels carried in a label stack instead of looking up a network-layer address at every hop. Architecture in RFC 3031.
Like I'm five A way of sending parcels by reading a small sticker on them instead of the full address.
Used in RFC 2209 RFC 2430 RFC 2475 RFC 2547 RFC 2549 RFC 2682 RFC 2702 RFC 2764 RFC 2917 RFC 2998 RFC 3031 RFC 3032 RFC 3033 RFC 3034 RFC 3035 RFC 3036 RFC 3037 RFC 3038 RFC 3063 RFC 3107 RFC 3140 RFC 3209 RFC 3210 RFC 3212 and 716 more
- MPLS Transport Profile
A profile of MPLS developed jointly by the IETF and ITU-T to support the capabilities and functionality of a packet transport network.
Like I'm five A version of MPLS shaped to work like the big, reliable pipes that phone companies use to carry traffic.
- MRU
Maximum Receive Unit. The largest Information field, including padding, that a PPP end can receive. The default is 1500 octets and it can be changed by LCP negotiation.
Like I'm five The biggest message a computer says it can handle in one go.
Used in RFC 1172 RFC 1331 RFC 1471 RFC 1548 RFC 1598 RFC 1638 RFC 1661 RFC 1962 RFC 1967 RFC 1973 RFC 1974 RFC 1979 RFC 1990 RFC 2363 RFC 2364 RFC 2419 RFC 2516 RFC 9174
- MSRP
The Message Session Relay Protocol, which sends a series of instant messages inside a session that two endpoints set up with SIP and SDP.
Like I'm five A way to send chat messages inside a call set up between two programs.
Used in RFC 5547 RFC 6135 RFC 6714 RFC 7573 RFC 7701 RFC 7702 RFC 7977 RFC 8591 RFC 8873
- MTA-STS
A policy mechanism that lets a mail domain publish which MX hostnames are acceptable and that TLS should be used. Senders can use it to validate the server name.
Like I'm five A sign a mail domain posts saying which doors are the real ones and that they must be locked.
- MTU (Maximum Transmission Unit)
The largest packet, measured in bytes, that a particular network link can carry in one piece. Ethernet's is 1500 bytes. In RFC 1191 the size counts the IP header and data but not lower-level headers.
Like I'm five The biggest box that fits through one particular door. Each door on the road can be a different size.
Used in RFC 791 RFC 792 RFC 817 RFC 877 RFC 879 RFC 894 RFC 1009 RFC 1042 RFC 1044 RFC 1055 RFC 1063 RFC 1088 RFC 1122 RFC 1132 RFC 1144 RFC 1149 RFC 1188 RFC 1191 RFC 1201 RFC 1209 RFC 1213 RFC 1242 RFC 1326 RFC 1332 and 302 more
- MULTI_EXIT_DISC (MED)
An optional non-transitive BGP attribute that a neighbouring AS can set to suggest which of several entry points into its network it would like traffic to use. Lower values are preferred, and values are only compared between routes from the same neighbouring AS.
Like I'm five A neighbour saying, "if you have a choice, please use my front door, not my back door."
Used in RFC 1745 RFC 1773 RFC 3345 RFC 4271 RFC 4451 RFC 5004 RFC 5065 RFC 7311 RFC 7947 RFC 9026
- Multi-homing
Having more than one IP address on an endpoint. SCTP monitors the paths with heartbeats and moves traffic to another address if the primary path fails.
Like I'm five Having two front doors, so if one is blocked you use the other.
Used in RFC 799 RFC 878 RFC 940 RFC 946 RFC 1930 RFC 2181 RFC 2960 RFC 3221 RFC 3286 RFC 3436 RFC 4080 RFC 4165 RFC 4423 RFC 4666 RFC 4960 RFC 5062 RFC 5221 RFC 5658 RFC 6317 RFC 6724 RFC 7291 RFC 7309 RFC 8518 RFC 9744
- Multi-Segment Pseudowire
A pseudowire built from several connected segments that cross intermediate switching provider edge routers between the two terminating routers.
Like I'm five A virtual wire made of several shorter wires joined end to end.
- Multi-streaming
Carrying several independent message streams in one SCTP association, so a lost packet in one stream delays only that stream.
Like I'm five Several checkout lanes instead of one, so a stuck cart blocks only its own lane.
Used in RFC 2960 RFC 3057 RFC 3257 RFC 3286 RFC 3331 RFC 3436 RFC 3758 RFC 3868 RFC 3873 RFC 4165 RFC 4168 RFC 4233 RFC 4960 RFC 5043 RFC 5811 RFC 6083 RFC 6458 RFC 6525 RFC 6526 RFC 7496 RFC 7933 RFC 8260 RFC 8303 RFC 8831 and 1 more
- Multicast
Sending one IP datagram to a group of hosts identified by a single class D address, so only members receive it.
Like I'm five Sending a message to a group chat instead of one person or everyone.
Used in RFC 824 RFC 907 RFC 919 RFC 922 RFC 955 RFC 966 RFC 988 RFC 991 RFC 992 RFC 1001 RFC 1045 RFC 1060 RFC 1062 RFC 1070 RFC 1075 RFC 1088 RFC 1112 RFC 1117 RFC 1166 RFC 1188 RFC 1201 RFC 1209 RFC 1221 RFC 1229 and 716 more
- Multicast Address
An IP address in the class D range (224.0.0.0 to 239.255.255.255) that identifies a host group rather than a single host.
Like I'm five A special IP address that reaches many computers at once.
- Multicast group
A set of hosts identified by a multicast IP address (224.0.0.0/4 in IPv4, ff00::/8 in IPv6) that receive the same data stream sent to that address.
Like I'm five A mailbox address that many people can read from at once. When you send mail to that address, everyone subscribed to the group gets a copy.
- Multicast Listener Discovery
A protocol that allows IPv6 hosts to report their multicast group memberships to neighboring routers.
Like I'm five The IPv6 way for devices to ask for multicast streams.
Used in RFC 3590 RFC 3810 RFC 5186 RFC 5790 RFC 7411 RFC 8652 RFC 9166 RFC 9398
- Multicast Listener Discovery
A protocol (MLD in IPv6) that allows hosts to notify routers that they wish to receive multicast packets for a particular group address.
Like I'm five A way for a device to say "I want to listen to broadcasts from this group."
- Multicast router
A router that forwards multicast datagrams between networks and uses IGMP queries to learn which groups have members on each attached network.
Like I'm five A helper who carries club messages to other streets that have members.
Used in RFC 1112 RFC 2022 RFC 2191 RFC 2236 RFC 2365 RFC 2710 RFC 2887 RFC 2934 RFC 3376 RFC 3488 RFC 3569 RFC 3618 RFC 3810 RFC 3973 RFC 4286 RFC 4541 RFC 4601 RFC 4604 RFC 4605 RFC 4608 RFC 4624 RFC 5059 RFC 5060 RFC 5132 and 34 more
- Multicast Routing
The process of forwarding packets from a single source to multiple receivers, using routing protocols that build multicast distribution trees across a network.
Like I'm five Sending one packet to reach many destinations at once.
- Multicast scope
A 4-bit value in an IPv6 multicast address that limits how far packets sent to that group may travel. Examples are Link-Local, Site-Local and Global.
Like I'm five How far a group message is allowed to travel, like a shout in a room versus across a stadium.
- Multicast Source Discovery Protocol
A protocol in which RPs tell their peers which multicast sources are active, using Source Active messages. It keeps multiple RPs consistent about active sources.
Like I'm five A way for meeting spots to tell each other who is currently broadcasting.
- Multihoming
Connecting a network to more than one service provider, usually for reliability. It makes the site harder to aggregate into any one provider's route.
Like I'm five Having two roads to your house so one can close.
Used in RFC 1519 RFC 1629 RFC 1772 RFC 1787 RFC 1998 RFC 2050 RFC 2071 RFC 2260 RFC 2772 RFC 2874 RFC 3056 RFC 3111 RFC 3178 RFC 3257 RFC 3554 RFC 3704 RFC 3873 RFC 4116 RFC 4168 RFC 4191 RFC 4218 RFC 4219 RFC 4555 RFC 4632 and 100 more
- Multilink PPP
An extension of PPP that splits packets into numbered fragments using begin and end bits and a sequence number, so they can be sent and reassembled at the other end.
Like I'm five Cutting a long letter into numbered pages so the reader can put it back together.
- Multipart boundary
A string chosen by the sender, 1 to 70 characters long, that separates the parts of a multipart body. Each delimiter line is two hyphens plus the boundary, and the last has two extra hyphens.
Like I'm five A code word written on divider cards between papers in an envelope, so you can tell where one paper stops and the next begins.
Used in RFC 1341 RFC 1563 RFC 1740 RFC 1820 RFC 1847 RFC 1848 RFC 1873 RFC 1892 RFC 2046 RFC 2049 RFC 2112 RFC 2183 RFC 2387 RFC 2392 RFC 2557 RFC 2848 RFC 3156 RFC 3801 RFC 5621 RFC 5703 RFC 6522 RFC 7578 RFC 7852 RFC 8058 and 3 more
- Multipath TCP
A modified version of TCP that supports the simultaneous use of multiple paths between two hosts. It presents one TCP-like connection to the application.
Like I'm five A conversation that uses several roads at once instead of just one.
- Multiplexing
Sharing one connection among several independent streams by labeling each piece of data with the stream it belongs to. SSH uses channel numbers for this.
Like I'm five Sending lots of different letters in one mailbag, each with the right name on the envelope.
Used in RFC 7 RFC 8 RFC 9 RFC 793 RFC 814 RFC 817 RFC 905 RFC 907 RFC 1008 RFC 1356 RFC 1547 RFC 1661 RFC 1692 RFC 1795 RFC 1859 RFC 1989 RFC 1990 RFC 2115 RFC 2341 RFC 2371 RFC 2427 RFC 3080 RFC 3153 RFC 3336 and 47 more
- Multipoint Control Unit (MCU)
A device that connects two or more endpoints into one multimedia conference. It can mix, switch or compose the media it receives before sending it on.
Like I'm five A switchboard that joins several rooms into one big call.
- Multipoint LDP
Extensions to LDP, also called mLDP, for creating point-to-multipoint and multipoint-to-multipoint label switched paths.
Like I'm five A way for the tunnel to build lanes that branch out to many places.
- Multipoint relay (MPR)
A neighbor selected by an OLSRv2 router to forward its flooded messages, or to be used for routing. Choosing a limited set of relays reduces the number of retransmissions needed.
Like I'm five A chosen helper neighbor who passes your news along so everyone does not have to shout.
Used in RFC 3626 RFC 5449 RFC 7181 RFC 7184 RFC 7185 RFC 7722
- Mutual authentication
An exchange in which both ends prove their identity to each other, rather than only one side proving itself to the other.
Like I'm five Both of you show the secret handshake, not just one of you.
Used in RFC 1411 RFC 1507 RFC 2716 RFC 2759 RFC 4746 RFC 4764 RFC 5418 RFC 5734 RFC 8120
- MVPN
A multicast VPN: a BGP/MPLS IP VPN that also carries multicast traffic between customer sites. Provider Edge routers exchange customer multicast routing information using either PIM or BGP.
Like I'm five A private network service that can send one stream to many sites at once.
- MX record
A DNS resource record naming a mail exchanger for a domain, with a preference value used to rank which to try first.
Like I'm five A sign that says "deliver mail for this house to this post office".
Used in RFC 821 RFC 974 RFC 1031 RFC 1033 RFC 1123 RFC 1183 RFC 1211 RFC 1279 RFC 1383 RFC 1386 RFC 1480 RFC 1530 RFC 1537 RFC 1569 RFC 1703 RFC 1713 RFC 1846 RFC 1912 RFC 1985 RFC 2142 RFC 2151 RFC 2163 RFC 2181 RFC 2219 and 26 more