In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction.[1] The MTU relates to, but is not identical to the maximum frame size that can be transported on the data link layer, e.g. Ethernet frame.
The fields of the IP packet are as follows:. Version —Indicates the version of this IP datagram. IP Header Length (IHL) —Indicates the datagram header length in 32-bit words. Type-of-Service —Specifies how a particular upper-layer protocol would like the current datagram to be handled. Datagrams can be assigned various levels of importance using this field. Jul 30, 2019. Aug 23, 2019. TCP/IP carefully defines how information moves from sender to receiver. First, application programs send messages or streams of data to one of the Internet Transport Layer Protocols, either the User Datagram Protocol (UDP) or the Transmission Control Protocol (TCP).These protocols receive the data from the application, divide it into smaller pieces called packets, add a destination address. The Internet protocol suite is the conceptual model and set of communications protocols used in the Internet and similar computer networks.It is commonly known as TCP/IP because the foundational protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP). During its development, versions of it were known as the Department of Defense (DoD) model because the. Mar 29, 2019. Which protocol translates TCP/IP addresses to MAC addresses? After you configure packet filtering, users on the network are no longer able to download files. What did you do to create this problem. You blocked port 21. Which protocol is used to send email messages?
Larger MTU is associated with reduced overhead. Smaller MTU values can reduce network delay. In many cases, MTU is dependent on underlying network capabilities and must be adjusted manually or automatically so as to not exceed these capabilities. MTU parameters may appear in association with a communications interface or standard. Some systems may decide MTU at connect time.
Applicability[edit]
MTUs apply to communications protocols and network layers. The MTU is specified in terms of bytes or octets of the largest PDU that the layer can pass onwards. MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.). Standards (Ethernet, for example) can fix the size of an MTU; or systems (such as point-to-point serial links) may decide MTU at connect time.
Underlying data link and physical layers usually add overhead to the network layer data to be transported, so for a given maximum frame size of a medium one needs to subtract the amount of overhead to calculate that medium's MTU. For example, with Ethernet, the maximum frame size is 1518 bytes, 18 bytes of which are overhead (header and frame check sequence), resulting in an MTU of 1500 bytes.
Tradeoffs[edit]
A larger MTU brings greater efficiency because each network packet carries more user data while protocol overheads, such as headers or underlying per-packet delays, remain fixed; the resulting higher efficiency means an improvement in bulk protocol throughput. A larger MTU also requires processing of fewer packets for the same amount of data. In some systems, per-packet-processing can be a critical performance limitation.
However, this gain is not without a downside. Large packets occupy a slow link for more time than a smaller packet, causing greater delays to subsequent packets, and increasing network delay and delay variation. For example, a 1500-byte packet, the largest allowed by Ethernet at the network layer, ties up a 14.4k modem for about one second.
Large packets are also problematic in the presence of communications errors. If no forward error correction is used, corruption of a single bit in a packet requires that the entire packet be retransmitted, which can be costly. At a given bit error rate, larger packets are more susceptible to corruption. Their greater payload makes retransmissions of larger packets take longer. Despite the negative effects on retransmission duration, large packets can still have a net positive effect on end-to-end TCP performance.[2]
Internet protocol[edit]
The Internet protocol suite was designed to work over many different networking technologies, each of which may use packets of different sizes. While a host will know the MTU of its own interface and possibly that of its peers (from initial handshakes), it will not initially know the lowest MTU in a chain of links to other peers. Another potential problem is that higher-level protocols may create packets larger than even the local link supports.
IPv4 allows fragmentation which divides the datagram into pieces, each small enough to accommodate a specified MTU limitation. This fragmentation process takes place at the internet layer. The fragmented packets are marked so that the IP layer of the destination host knows it should reassemble the packets into the original datagram.
All fragments of a packet must arrive for the packet to be considered received. If the network drops any fragment, the entire packet is lost.
When the number of packets that must be fragmented or the number of fragments is great, fragmentation can cause unreasonable or unnecessary overhead. For example, various tunneling situations may exceed the MTU by very little as they add just a header's worth of data. The addition is small, but each packet now has to be sent in two fragments, the second of which carries very little payload. The same amount of payload is being moved, but every intermediate router has to forward twice as many packets.
The Internet Protocol requires that hosts must be able to process IP datagrams of at least 576 bytes (for IPv4) or 1280 bytes (for IPv6). However, this does not preclude link layers with an MTU smaller than this minimum MTU from conveying IP data. For example, according to IPv6's specification, if a particular link layer cannot deliver an IP datagram of 1280 bytes in a single frame, then the link layer must provide its own fragmentation and reassembly mechanism, separate from the IP fragmentation mechanism, to ensure that a 1280-byte IP datagram can be delivered, intact, to the IP layer.
MTUs for common media[edit]
In the context of Internet Protocol, MTU refers to the maximum size of an IP packet that can be transmitted without fragmentation over a given medium. Auto mouse click mac download. The size of an IP packet includes IP headers but excludes headers from the link layer. In the case of an Ethernet frame this adds an overhead of 18 bytes, or 22 bytes with an IEEE 802.1Q tag for VLAN tagging or class of service.
The MTU should not be confused with the minimum datagram size that all hosts must be prepared to accept. This is 576 bytes for IPv4[3] and of 1280 bytes for IPv6.[4]
| Media for IP transport | Maximum transmission unit (bytes) | Notes |
|---|---|---|
| Internet IPv4 path MTU | At least 68,[5] max of 64 KiB[6] | Systems may use Path MTU Discovery[7] to find the actual path MTU. Routing from larger MTU to smaller MTU causes IP fragmentation. |
| Internet IPv6 path MTU | At least 1280,[8] max of 64 KiB, but up to 4 GiB with optional jumbogram[9] | Systems must use Path MTU Discovery[10] to find the actual path MTU. |
| Ethernet v2 | 1500[11] | Nearly all IP over Ethernet implementations use the Ethernet II frame format. |
| Ethernet with LLC and SNAP | 1492[12] | |
| Ethernet jumbo frames | 1501 – 9202[13] or more[14] | The limit varies by vendor. For correct interoperation, frames should be no larger than the maximum frame size supported by any device on the network segment.[15] Jumbo frames are usually only seen in special-purpose networks. |
| PPPoE v2 | 1492[16] | Ethernet II MTU (1500) less PPPoE header (8) |
| DS-Lite over PPPoE | 1452 | Ethernet II MTU (1500) less PPPoE header (8) and IPv6 header (40) |
| PPPoE jumbo frames | 1493 – 9190 or more[17] | Ethernet Jumbo Frame MTU (1501 - 9198) less PPPoE header (8) |
| IEEE 802.11 Wi-Fi (WLAN) | 2304[18] | The maximum MSDU size is 2304 before encryption. WEP will add 8 bytes, WPA-TKIP 20 bytes, and WPA2-CCMP 16 bytes. |
| Token Ring (802.5) | 4464 | |
| FDDI | 4352[7] |
Ethernet maximum frame size[edit]
The IP MTU and Ethernet maximum frame size are configured separately. In Ethernet switch configuration, MTU may refer to Ethernet maximum frame size. In Ethernet-based routers, MTU normally refers to the IP MTU. If jumbo frames are allowed in a network, the IP MTU should also be adjusted upwards to take advantage of this.
Since the IP packet is carried by an Ethernet frame, the Ethernet frame has to be larger than the IP packet. With the normal untagged Ethernet frame overhead of 18 bytes, the Ethernet maximum frame size is 1518 bytes. If a 1500 byte IP packet is to be carried over a tagged Ethernet connection, the Ethernet frame maximum size needs to be 1522 due to the larger size of an 802.1Q tagged frame. 802.3ac increases the standard Ethernet maximum frame size to accommodate this.
Path MTU Discovery[edit]
The Internet Protocol defines the path MTU of an Internet transmission path as the smallest MTU supported by any of the hops on the path between a source and destination. Put another way, the path MTU is the largest packet size that can traverse this path without suffering fragmentation.
RFC1191 (IPv4) and RFC1981 (IPv6) describe Path MTU Discovery, a technique for determining the path MTU between two IP hosts. It works by sending packets with the DF (don't fragment) option in the IP header set. Any device along the path whose MTU is smaller than the packet will drop such packets and send back an ICMP Destination Unreachable (Datagram Too Big) message which indicates its MTU. This information allows the source host to reduce its assumed path MTU appropriately. The process repeats until the MTU becomes small enough to traverse the entire path without fragmentation.
Standard Ethernet supports an MTU of 1500 bytes and Ethernet implementation supporting jumbo frames, allow for an MTU up to 9000 bytes. However, border protocols like PPPoE will reduce this. Path MTU Discovery exposes the difference between the MTU seen by Ethernet end-nodes and the Path MTU
Unfortunately, increasing numbers of networks drop ICMP traffic (for example, to prevent denial-of-service attacks), which prevents path MTU discovery from working. RFC4821, Packetization Layer Path MTU Discovery, describes a Path MTU Discovery technique which responds more robustly to ICMP filtering. In an IP network, the path from the source address to the destination address may change in response to various events (load-balancing, congestion, outages, etc.) and this could result in the path MTU changing (sometimes repeatedly) during a transmission, which may introduce further packet drops before the host finds a new reliable MTU.
A failure of Path MTU Discovery carries the possible result of making some sites behind badly configured firewalls unreachable. A connection with mismatched MTU may work for low-volume data but fail as soon as a host sends a large block of data. For example, with Internet Relay Chat a connecting client might see the initial messages up to and including the initial ping (sent by the server as an anti-spoofing measure), but get no response after that. This is because the large set of welcome messages sent at that point are packets that exceed the path MTU. One can possibly work around this, depending on which part of the network one controls; for example one can change the MSS (maximum segment size) in the initial packet that sets up the TCP connection at one's firewall.
In other contexts[edit]
MTU is sometimes used to describe the maximum PDU sizes in communication layers other than the network layer.
- Cisco Systems use L2 MTU for the maximum frame size.[19]
- Dell/Force10 use MTU for the maximum frame size.[20]
- Hewlett Packard used just MTU for the maximum frame size including the optional IEEE 802.1Q tag.[21]
- Juniper Networks use several MTU terms: Physical Interface MTU (L3 MTU plus some unspecified protocol overhead), Logical Interface MTU (consistent with IETF MTU) and Maximum MTU (maximum configurable frame size for jumbo frames).[22]
The transmission of a packet on a physical network segment that is larger than the segment's MTU is known as jabber. This is almost always caused by faulty devices.[23]Network switches and some repeater hubs have a built-in capability to detect when a device is jabbering.[24][25]
References[edit]
- ^RFC 791. p. 25. doi:10.17487/RFC0791.
- ^Murray, David; Terry Koziniec; Kevin Lee; Michael Dixon (2012). 'Large MTUs and internet performance'. 2012 IEEE 13th International Conference on High Performance Switching and Routing. pp. 82–87. doi:10.1109/HPSR.2012.6260832. ISBN978-1-4577-0833-6.
- ^RFC 791. p. 24. doi:10.17487/RFC0791.
Every internet destination must be able to receive a datagram of 576 octets either in one piece or in fragments to be reassembled.
- ^RFC 2460. p. 13. doi:10.17487/RFC2460.
- ^RFC 791. p. 24. doi:10.17487/RFC0791.
Every internet module must be able to forward a datagram of 68 octets without further fragmentation.
- ^RFC 791. p. 12. doi:10.17487/RFC0791.
Total Length is the length of the datagram, measured in octets, including internet header and data. This field allows the length of a datagram to be up to 65,535 octets.
- ^ abRFC 1191. doi:10.17487/RFC1191.
- ^RFC2460
- ^RFC2675, p. 1, 'The IPv6 header [IPv6] has a 16-bit Payload Length field and, therefore, supports payloads up to 65,535 octets long. This document specifies an IPv6 hop-by-hop option, called the Jumbo Payload option, that carries a 32-bit length field in order to allow transmission of IPv6 packets with payloads between 65,536 and 4,294,967,295 octets in length. Packets with such long payloads are referred to as 'jumbograms'.'
- ^RFC6145
- ^ Network Working Group of the IETF, RFC894: A Standard for the Transmission of IP Datagrams over Ethernet Networks, Page 1, 'The maximum length of the data field of a packet sent over an Ethernet is 1500 octets, thus the maximum length of an IP datagram sent over an Ethernet is 1500 octets.', ERRATA
- ^IEEE 802.3[page needed]
- ^Scott Hogg (2013-03-06), Jumbo Frames, Network World, retrieved 2013-08-05,
Most network devices support a jumbo frame size of 9216 bytes.
- ^Juniper Networks (2020-03-23), Physical Interface Properties, retrieved 2020-05-01
- ^Joe St Sauver (2003-02-04). 'Practical Issues Associated With 9K MTUs'(PDF). uoregon.edu. p. 67. Retrieved 2016-12-15.
you still need to insure that ALL upstream Ethernet switches, including any switches in your campus core, are ALSO jumbo frame capable
- ^RFC2516 with the standard Ethernet MTU of 1500 bytes; extensions exist
- ^RFC4638
- ^802.11-2012, page 413, section 8.3.2.1
- ^'Configure and Verify Maximum Transmission Unit on Cisco Nexus Platforms'. Cisco. 2016-11-29. Document ID:118994. Retrieved 2017-01-04.
- ^'How to configure MTU (Maximum Transmission Unit) for Jumbo Frames on Dell Networking Force10 switches'. Dell. 2016-06-02. Article ID: HOW10713. Retrieved 2017-01-06.
- ^'Jumbo Frames'. HP Networking 2910al Switches Management and Configuration Guide. Hewlett Packard. November 2011. P/N 5998-2874.
- ^'SRX Series Services Gateways for the Branch Physical Interface Modules Reference: MTU Default and Maximum Values for Physical Interface Modules'. Juniper. 2014-01-03. Retrieved 2017-01-04.
- ^jabber, The Network Encyclopedia, retrieved 2016-07-28
- ^show interfaces, Juniper Networks, retrieved 2016-07-28
- ^IEEE 802.3 27.3.1.7 Receive jabber functional requirements
External links[edit]
- Marc Slemko (January 18, 1998). 'Path MTU Discovery and Filtering ICMP'. Archived from the original on August 9, 2011. Retrieved 2007-09-02.
- mturoute – a console utility for debugging mtu problems
Network administrators can use this information to make sure that Mac computers and other Apple devices can connect to services such as the App Store and Apple's software-update servers.
Ports used by Apple products
This is a quick-reference guide showing common examples, not a comprehensive list of ports. This guide is updated periodically with information available at the time of publication.
Some software might use different ports and services, so it can be helpful to use port-watching software when deciding how to set up firewalls or similar access-control schemes.
Some services might use more than one of these ports. For example, a VPN service can use up to four different ports. When you find a product in this list, search (Command-F) in your browser for that name, then repeat your search (Command-G) to locate all occurrences of that product.
Some firewalls allow selective configuration of UDP or TCP ports with the same number, so it's important to know the type of port you're configuring. For example, NFS can use TCP 2049, UDP 2049, or both. If your firewall doesn't allow you to specify the type of port, configuring one type of port probably configures the other.
| Port | TCP or UDP | Service or protocol name1 | RFC2 | Service name3 | Used by |
|---|---|---|---|---|---|
| 7 | TCP/UDP | echo | 792 | echo | — |
| 20 | TCP | File Transport Protocol (FTP) | 959 | ftp-data | — |
| 21 | TCP | FTP control | 959 | ftp | — |
| 22 | TCP | Secure Shell (SSH), SSH File Transfer Protocol (SFTP), and Secure copy (scp) | 4253 | ssh | Xcode Server (hosted and remote Git+SSH; remote SVN+SSH) |
| 23 | TCP | Telnet | 854 | telnet | — |
| 25 | TCP | Simple Mail Transfer Protocol (SMTP) | 5321 | smtp | Mail (sending email); iCloud Mail (sending email) |
| 53 | TCP/UDP | Domain Name System (DNS) | 1034 | domain | — |
| 67 | UDP | Bootstrap Protocol Server (BootP, bootps) | 951 | bootps | NetBoot via DHCP |
| 68 | UDP | Bootstrap Protocol Client (bootpc) | 951 | bootpc | NetBoot via DHCP |
| 69 | UDP | Trivial File Transfer Protocol (TFTP) | 1350 | tftp | — |
| 79 | TCP | Finger | 1288 | finger | — |
| 80 | TCP | Hypertext Transfer Protocol (HTTP) | 2616 | http | World Wide Web, FaceTime, iMessage, iCloud, QuickTime Installer, Maps, iTunes U, Apple Music, iTunes Store, Podcasts, Internet Radio, Software Update (OS X Lion or earlier), Mac App Store, RAID Admin, Backup, Calendar, WebDAV, Final Cut Server, AirPlay, macOS Internet Recovery, Profile Manager, Xcode Server (Xcode app, hosted and remote Git HTTP, remote SVN HTTP) |
| 88 | TCP | Kerberos | 4120 | kerberos | Kerberos, including Screen Sharing authentication |
| 106 | TCP | Password Server (unregistered use) | — | 3com-tsmux | macOS Server Password Server |
| 110 | TCP | Post Office Protocol (POP3), Authenticated Post Office Protocol (APOP) | 1939 | pop3 | Mail (receiving email) |
| 111 | TCP/UDP | Remote Procedure Call (RPC) | 1057, 1831 | sunrpc | Portmap (sunrpc) |
| 113 | TCP | Identification Protocol | 1413 | ident | — |
| 119 | TCP | Network News Transfer Protocol (NNTP) | 3977 | nntp | Apps that read newsgroups. |
| 123 | UDP | Network Time Protocol (NTP) | 1305 | ntp | Date & Time preferences, network time server synchronization, Apple TV network time server sync |
| 137 | UDP | Windows Internet Naming Service (WINS) | — | netbios-ns | — |
| 138 | UDP | NETBIOS Datagram Service | — | netbios-dgm | Windows Datagram Service, Windows Network Neighborhood |
| 139 | TCP | Server Message Block (SMB) | — | netbios-ssn | Microsoft Windows file and print services, such as Windows Sharing in macOS |
| 143 | TCP | Internet Message Access Protocol (IMAP) | 3501 | imap | Mail (receiving email) |
| 161 | UDP | Simple Network Management Protocol (SNMP) | 1157 | snmp | — |
| 192 | UDP | OSU Network Monitoring System | — | osu-nms | AirPort Base Station PPP status or discovery (certain configurations), AirPort Admin Utility, AirPort Express Assistant |
| 311 | TCP | Secure server administration | — | asip-webadmin | Server app, Server Admin, Workgroup Manager, Server Monitor, Xsan Admin |
| 312 | TCP | Xsan administration | — | vslmp | Xsan Admin (OS X Mountain Lion v10.8 and later) |
| 389 | TCP | Lightweight Directory Access Protocol (LDAP) | 4511 | ldap | Apps that look up addresses, such as Mail and Address Book |
| 427 | TCP/UDP | Service Location Protocol (SLP) | 2608 | svrloc | Network Browser |
| 443 | TCP | Secure Sockets Layer (SSL or HTTPS) | 2818 | https | TLS websites, iTunes Store, Software Update (OS X Mountain Lion and later), Spotlight Suggestions, Mac App Store, Maps, FaceTime, Game Center, iCloud authentication and DAV Services (Contacts, Calendars, Bookmarks), iCloud backup and apps (Calendars, Contacts, Find My iPhone, Find My Friends, Mail, iMessage, Documents & Photo Stream), iCloud Key Value Store (KVS), iPhoto Journals, AirPlay, macOS Internet Recovery, Profile Manager, Dictation, Siri, Xcode Server (hosted and remote Git HTTPS, remote SVN HTTPS, Apple Developer registration), Push notifications (if necessary) |
| 445 | TCP | Microsoft SMB Domain Server | — | microsoft-ds | — |
| 464 | TCP/UDP | kpasswd | 3244 | kpasswd | — |
| 465 | TCP | Message Submission for Mail (Authenticated SMTP) | smtp (legacy) | Mail (sending mail) | |
| 500 | UDP | ISAKMP/IKE | 2408 | isakmp | macOS Server VPN service |
| 500 | UDP | Wi-Fi Calling | 5996 | IKEv2 | Wi-Fi Calling |
| 514 | TCP | shell | — | shell | — |
| 514 | UDP | Syslog | — | syslog | — |
| 515 | TCP | Line Printer (LPR), Line Printer Daemon (LPD) | — | printer | Printing to a network printer, Printer Sharing in macOS |
| 532 | TCP | netnews | — | netnews | — |
| 548 | TCP | Apple Filing Protocol (AFP) over TCP | — | afpovertcp | AppleShare, Personal File Sharing, Apple File Service |
| 554 | TCP/UDP | Real Time Streaming Protocol (RTSP) | 2326 | rtsp | AirPlay, QuickTime Streaming Server (QTSS), streaming media players |
| 587 | TCP | Message Submission for Mail (Authenticated SMTP) | 4409 | submission | Mail (sending mail), iCloud Mail (SMTP authentication) |
| 600–1023 | TCP/UDP | Mac OS X RPC-based services | — | ipcserver | NetInfo |
| 623 | UDP | Lights-Out-Monitoring | — | asf-rmcp | Lights Out Monitoring (LOM) feature of Intel-based Xserve computers, Server Monitor |
| 625 | TCP | Open Directory Proxy (ODProxy) (unregistered use) | — | dec_dlm | Open Directory, Server app, Workgroup Manager; Directory Services in OS X Lion or earlier This port is registered to DEC DLM |
| 626 | TCP | AppleShare Imap Admin (ASIA) | — | asia | IMAP administration (Mac OS X Server v10.2.8 or earlier) |
| 626 | UDP | serialnumberd (unregistered use) | — | asia | Server serial number registration (Xsan, Mac OS X Server v10.3 – v10.6) |
| 631 | TCP | Internet Printing Protocol (IPP) | 2910 | ipp | macOS Printer Sharing, printing to many common printers |
| 636 | TCP | Secure LDAP | — | ldaps | — |
| 660 | TCP | Server administration | — | mac-srvr-admin | Server administration tools for Mac OS X Server v10.4 or earlier, including AppleShare IP |
| 687 | TCP | Server administration | — | asipregistry | Server administration tools for Mac OS X Server v10.6 or earlier, including AppleShare IP |
| 749 | TCP/UDP | Kerberos 5 admin/changepw | — | kerberos-adm | — |
| 985 | TCP | NetInfo Static Port | — | — | — |
| 993 | TCP | Mail IMAP SSL | — | imaps | iCloud Mail (SSL IMAP) |
| 995 | TCP/UDP | Mail POP SSL | — | pop3s | — |
| 1085 | TCP/UDP | WebObjects | — | webobjects | — |
| 1099, 8043 | TCP | Remote RMI and IIOP Access to JBOSS | — | rmiregistry | — |
| 1220 | TCP | QT Server Admin | — | qt-serveradmin | Administration of QuickTime Streaming Server |
| 1640 | TCP | Certificate Enrollment Server | — | cert-responder | Profile Manager in macOS Server 5.2 and earlier |
| 1649 | TCP | IP Failover | — | kermit | — |
| 1701 | UDP | L2TP | — | l2f | macOS Server VPN service |
| 1723 | TCP | PPTP | — | pptp | macOS Server VPN service |
| 1900 | UDP | SSDP | — | ssdp | Bonjour |
| 2049 | TCP/UDP | Network File System (NFS) (version 3 and 4) | 3530 | nfsd | — |
| 2195 | TCP | Apple Push Notification Service (APNS) | — | — | Push notifications |
| 2196 | TCP | Apple Push Notification Service (APNS) | — | — | Feedback service |
| 2197 | TCP | Apple Push Notification Service (APNS) | — | — | Push notifications |
| 2336 | TCP | Mobile account sync | — | appleugcontrol | Home directory synchronization |
| 3004 | TCP | iSync | — | csoftragent | — |
| 3031 | TCP/UDP | Remote AppleEvents | — | eppc | Program Linking, Remote Apple Events |
| 3283 | TCP/UDP | Net Assistant | — | net-assistant | Apple Remote Desktop 2.0 or later (Reporting feature), Classroom app (command channel) |
| 3284 | TCP/UDP | Net Assistant | — | net-assistant | Classroom app (document sharing) |
| 3306 | TCP | MySQL | — | mysql | — |
| 3478–3497 | UDP | — | — | nat-stun-port - ipether232port | FaceTime, Game Center |
| 3632 | TCP | Distributed compiler | — | distcc | — |
| 3659 | TCP/UDP | Simple Authentication and Security Layer (SASL) | — | apple-sasl | macOS Server Password Server |
| 3689 | TCP | Digital Audio Access Protocol (DAAP) | — | daap | iTunes Music Sharing, AirPlay |
| 3690 | TCP/UDP | Subversion | — | svn | Xcode Server (anonymous remote SVN) |
| 4111 | TCP | XGrid | — | xgrid | — |
| 4398 | UDP | — | — | — | Game Center |
| 4488 | TCP | Apple Wide Area Connectivity Service | awacs-ice | ||
| 4500 | UDP | IPsec NAT Traversal | 4306 | ipsec-msft | macOS Server VPN service |
| 4500 | UDP | Wi-Fi Calling | 5996 | IKEv2 | Wi-Fi Calling |
| 5003 | TCP | FileMaker - name binding and transport | — | fmpro-internal | — |
| 5009 | TCP | (unregistered use) | — | winfs | AirPort Utility, AirPort Express Assistant |
| 5100 | TCP | — | — | socalia | macOS camera and scanner sharing |
| 5222 | TCP | XMPP (Jabber) | 3920 | jabber-client | Jabber messages |
| 5223 | TCP | Apple Push Notification Service (APNS) | — | — | iCloud DAV Services (Contacts, Calendars, Bookmarks), Push Notifications, FaceTime, iMessage, Game Center, Photo Stream |
| 5228 | TCP | — | — | — | Spotlight Suggestions, Siri |
| 5297 | TCP | — | — | — | Messages (local traffic) |
| 5350 | UDP | NAT Port Mapping Protocol Announcements | — | — | Bonjour |
| 5351 | UDP | NAT Port Mapping Protocol | — | nat-pmp | Bonjour |
| 5353 | UDP | Multicast DNS (MDNS) | 3927 | mdns | Bonjour, AirPlay, Home Sharing, Printer Discovery |
| 5432 | TCP | PostgreSQL | — | postgresql | Can be enabled manually in OS X Lion Server (previously enabled by default for ARD 2.0 Database) |
| 5897–5898 | UDP | (unregistered use) | — | — | xrdiags |
| 5900 | TCP | Virtual Network Computing (VNC) (unregistered use) | — | vnc-server | Apple Remote Desktop 2.0 or later (Observe/Control feature) Screen Sharing (Mac OS X 10.5 or later) |
| 5988 | TCP | WBEM HTTP | — | wbem-http | Apple Remote Desktop 2.x See also dmtf.org/standards/wbem. |
| 6970–9999 | UDP | — | — | — | QuickTime Streaming Server |
| 7070 | TCP | RTSP (unregistered use), Automatic Router Configuration Protocol (ARCP) | — | arcp | QuickTime Streaming Server (RTSP) |
| 7070 | UDP | RTSP alternate | — | arcp | QuickTime Streaming Server |
| 8000–8999 | TCP | — | — | irdmi | Web service, iTunes Radio streams |
| 8005 | TCP | Tomcat remote shutdown | — | — | — |
| 8008 | TCP | iCal service | — | http-alt | Mac OS X Server v10.5 or later |
| 8080 | TCP | Alternate port for Apache web service | — | http-alt | Also JBOSS HTTP in Mac OS X Server 10.4 or earlier |
| 8085–8087 | TCP | Wiki service | — | — | Mac OS X Server v10.5 or later |
| 8088 | TCP | Software Update service | — | radan-http | Mac OS X Server v10.4 or later |
| 8089 | TCP | Web email rules | — | — | Mac OS X Server v10.6 or later |
| 8096 | TCP | Web Password Reset | — | — | Mac OS X Server v10.6.3 or later |
| 8170 | TCP | HTTPS (web service/site) | — | — | Podcast Capture/podcast CLI |
| 8171 | TCP | HTTP (web service/site) | — | — | Podcast Capture/podcast CLI |
| 8175 | TCP | Pcast Tunnel | — | — | pcastagentd (such as for control operations and camera) |
| 8443 | TCP | iCal service (SSL) | — | pcsync-https | Mac OS X Server v10.5 or later (JBOSS HTTPS in Mac OS X Server 10.4 or earlier) |
| 8800 | TCP | Address Book service | — | sunwebadmin | Mac OS X Server v10.6 or later |
| 8843 | TCP | Address Book service (SSL) | — | — | Mac OS X Server v10.6 or later |
| 8821, 8826 | TCP | Stored | — | — | Final Cut Server |
| 8891 | TCP | ldsd | — | — | Final Cut Server (data transfers) |
| 9006 | TCP | Tomcat standalone | — | — | Mac OS X Server v10.6 or earlier |
| 9100 | TCP | Printing | — | — | Printing to certain network printers |
| 9418 | TCP/UDP | git pack transfer | — | git | Xcode Server (remote git) |
| 10548 | TCP | Apple Document Sharing Service | — | serverdocs | macOS Server iOS file sharing |
| 11211 | — | memcached (unregistered use) | — | — | Calendar Server |
| 16080 | TCP | — | — | — | Web service with performance cache |
| 16384–16403 | UDP | Real-Time Transport Protocol (RTP), Real-Time Control Protocol (RTCP) | — | connected, — | Messages (Audio RTP, RTCP; Video RTP, RTCP) |
| 16384–16387 | UDP | Real-Time Transport Protocol (RTP), Real-Time Control Protocol (RTCP) | — | connected, — | FaceTime, Game Center |
| 16393–16402 | UDP | Real-Time Transport Protocol (RTP), Real-Time Control Protocol (RTCP) | — | — | FaceTime, Game Center |
| 16403–16472 | UDP | Real-Time Transport Protocol (RTP), Real-Time Control Protocol (RTCP) | — | — | Game Center |
| 24000–24999 | TCP | — | — | med-ltp | Web service with performance cache |
| 42000–42999 | TCP | — | — | — | iTunes Radio streams |
| 49152–65535 | TCP | Xsan | — | — | Xsan Filesystem Access |
| 49152– 65535 | UDP | — | — | — | |
| 50003 | — | FileMaker server service | — | — | — |
| 50006 | — | FileMaker helper service | — | — | — |
1. The service registered with the Internet Assigned Numbers Authority, except where noted as “unregistered use.”
2. The number of a Request for Comment (RFC) document that defines the service or protocol. RFC documents are maintained by RFC Editor.
3. In the output of Terminal commands, the port number might be replaced by this Service Name, which is the label listed in /etc/services.
Tcp Ip Protocol Pdf
FaceTime is not available in all countries or regions.
Tcp Ip Application Protocols
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Tcp Ip Protocol Driver
The application firewall in macOS is not a port-based firewall. It controls access by app, instead of by port.