Socket number list
A registry of socket numbers and the network services assigned to them
Neigus, N. and J. Postel, "Socket number list", RFC 503, DOI 10.17487/RFC0503, April 1973, <https://www.rfc-editor.org/info/rfc503>.
@misc{rfc503,
series = {Request for Comments},
number = 503,
howpublished = {RFC 503},
publisher = {RFC Editor},
doi = {10.17487/RFC0503},
url = {https://www.rfc-editor.org/info/rfc503},
author = {N. Neigus and J. Postel},
title = {{Socket number list}},
pagetotal = 8,
year = 1973,
month = apr,
} RFC text
Network Working Group N. Neigus
Request for Comments: 503 J. Postel
NIC: 15747 13 April 1973
References: 349, 433
Socket Number List
This is a second pass at the specification of the socket numbers.
More sockets have been made available for experimental functions,
some new sockets have been assigned for network standard functions,
host specific functions and experimental functions, and the list of
available sockets for server hosts has been updated.
Following are the current assignments for socket numbers used for
public functions. Note that a socket number is a 40 bit quantity,
the first 8 bits being the host specification, the next 24 bits being
site specific, and the last 8 bits being user specified -- these last
8 bits are called the AEN [it stands for, cleverly enough, Another
Eightbit Number].
For the assignments here the value in the host field ranges across al
hosts (unless otherwise specified), the value in the 24 bit field is
zero, and the AEN is indicated here.
General Assignments:
Sockets Assignment
0 - 63 Network Wide Standard Functions
64 - 127 Host Specific Functions
128 - 223 Reserved for Future Use
224 - 255 Any Experimental Function
Particular Assignments:
Socket Assignment
1 Telnet
3 File Transfer
5 Remote Job Entry
7 Echo
9 Discard
11 Systat or who-is-on function
13 Date-Time function
15 Netstat or who-is-up function
19 Character Generator [e.g. TTYTST]
65 Speech Data Base @ 11-tx-2 (74)
67
69 CPYNET
71 NETRJS [EBCDIC]
73 NETRJS [ASCII]
75 NETRJS [TTY]
241 NCP Measurement
243 Survey Measurement
245 LINK
247 RSEXEC
249 RSEXEC
251 RSEXEC
The specifications for the assigned functions can be found in the
documents listed here:
Telnet NIC 7104
File Transfer NIC 7104
Remote Job Entry NIC 7104
Echo RFC 347
Discard RFC 348
Character Generator RFC 429
Speech Data Base SUR 37
Datacomputer [Murray @ CCA]
NCP Measurement RFC 388
Survey Data [Kampa @ NMC]
LINK [Bressler @ BBN]
RSEXEC [Thomas @ BBN]
There are several hosts performing public services on sockets which
conflict with the above scheme. We hope we can resolve these
conflicts with a minimum of disruption.
The following is a tabulation of socket numbers together with the
services offered. This listing is presented as an aid to network
users. If you know of a socket function which has been left out or
an entry which should be corrected or deleted please contact:
Jon Postel
3804 Boelter Hall
Computer Science Department
University of California
Los Angeles, CA. 90024
Phone: (213) 825-2368
NIC Ident - JBP
or
Nancy J. Neigus
Bolt Beranek and Newman
50 Moulton Street
Cambridge, Mass. 02138
Phone: (617) 661-0100
NIC Ident = NJN
We will be pleased to include socket/function information for other
than "official" sockets [e.g. Tip News].
1 UCLA-NMC
1 Telnet
3 File Transfer
241 NCP Measurement
243 Survey Data
2 SRI-ARC
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
13 DATE-TIME
69 CPYNET
3 UCSB
1 Telnet
5 UCSB RJS [not ARPANET standard]
7 Echo
9 Discard
1793, 1795, 1797, 1799, 1801, 2049 Graphics terminal sockets
x'701', '703', '705', '707', '709', '801' o'3401', '3403',
'3405', '3407', '3411', '4001'
4 UTAH
1 Telnet
3 File Transfer
5 Echo
7 CPYNET
9 SYSTAT
13 DATE-TIME
6 MIT-Multics
1 Telnet
3 File Transfer
8 SDC-Adept
1 Telnet
9 Harvard
1 Telnet
3 File Transfer
10 LL-67
1 Telnet
11 SAIL
1 Telnet
3 File Transfer
13 CASE
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
13 DATE-TIME
69 CPYNET
14 CMU
1 Telnet
3 File Transfer
15 ILLIAC-TENEX
1 Telnet
3 File Transfer
5 Echo
7 CPYNET
9 SYSTAT
13 DATE-TIME
16 NASA-AMES
1 Telnet
3 File Transfer
5 Sorry Remote Job Entry
7 Echo
9 Discard
241 NCP Measurement
23 USC-44
1 Telnet
31 CCA-TENEX
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
15 NETSTAT
35 UCSD
1 Telnet
65 UCLA-CCN
1 Telnet
3 File Transfer
7 Echo
9 Discard
71 NETRJS [EBCDIC]
73 NETRJS [ASCII]
75 NETRJS [TTY]
66 SRI-AI
1 Telnet
3 File Transfer
5 Echo
7 CPYNET
9 SYSTAT
11 Sorry NETSAT
69 BBN-TENEX (a)
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
13 DATE-TIME
15 NETSTAT
17 Oneliners
69 CPYNET
247 = x'F7' = o'367' TIP RSEXEC Facility
70 MIT-DMCG
1 Telnet
3 File Transfer
7 Network Status
9 Discard
74 LL-TX-2
1 Telnet
78 CMU-alt
1 Telnet
3 File Transfer
86 ISI-TENEX
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
13 DATE-TIME
69 CPYNET
133 BBN-TENEXB
1 Telnet
3 File Transfer
7 Echo
11 SYSTAT
13 DATE-TIME
15 NETSTAT
17 Oneliners
69 CPYNET
134 MIT-AI
1 Telnet
3 File Transfer
198 MIT-Mathlab
1 Telnet
3 File Transfer
User only hosts -- no server sockets
5 NCC
7 RAND
12 ILI-ANTS
19 NBS-ANTS
32 PARC-MAXC (currently)
138 LL-TSP
197 BBN-1D
ISO Plain Language
On this page
§1What a Socket Number Identifies
RFC 503 is a second specification of socket numbers. It updates the list of sockets available for server hosts and adds assignments for standard, host-specific and experimental functions.
A socket number is a 40-bit quantity. Its first 8 bits specify the host, the next 24 bits are site-specific, and the last 8 bits are the AEN, or Another Eightbit Number. For the assignments in this list, the host field ranges across all hosts and the 24-bit field is zero unless specified otherwise.
A socket number combines a host identifier with a number for a service. This list uses the service part to record the assignments shared across the network.
§2Ranges and Service Assignments
The RFC assigns sockets 0–63 to network-wide standard functions, 64–127 to host-specific functions, 128–223 as reserved for future use, and 224–255 to experimental functions. The specific list includes Telnet at socket 1, File Transfer at 3, Remote Job Entry at 5 and Echo at 7.
It also lists socket services by host, including user-only hosts with no server sockets. The list is presented as an aid to network users, and the RFC asks readers to report missing or incorrect entries.
The ranges separate shared services, services specific to a host, numbers held for future use, and experimental services. The host-by-host table records which services each listed machine offers.
§3Maintaining the List
The authors say more sockets had become available for experimental functions and that new assignments had been made. They also note that some public services used sockets that conflicted with the scheme, and hoped to resolve those conflicts with minimal disruption.
RFC 503 superseded RFC 433 according to the unit metadata, and was itself later obsoleted by RFC 739.
The registry was updated as assignments changed, although the RFC notes that some existing services conflicted with the scheme. RFC 739 later replaced this list.