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Why do popular TCP-using services have UDP as well as TCP entries in /etc/services?
Why is my TCP throughput much greater than UDP throughput?How to permit any user (mysql, apache, etc) to use any TCP or UDP port?Why is my UDP bandwidth significantly lower than TCP bandwidth in iperfWhy doesn't NAT reserve ports from the machine's TCP and UDP port pool?Unknown runlevel on Ubuntu 14.04, services not starting on bootUsing tc, I want TCP and UDP to use the same bufferWhy do I have 2 SSH services?
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I'm reading a book on network programming with Go. One of the chapters deals with the /etc/services file. Something I noticed while exploring this file is that certain popular entries like HTTP and SSH, both of which use TCP at the transport layer, have a second entry for UDP. For example on Ubuntu 14.04:
ubuntu@vm1:~$ grep ssh /etc/services
ssh 22/tcp # SSH Remote Login Protocol
ssh 22/udp
ubuntu@vm1:~$ grep http /etc/services
http 80/tcp www # WorldWideWeb HTTP
http 80/udp # HyperText Transfer Protocol
Anyone know why these have two entries? I don't believe SSH or HTTP ever use UDP (confirmed by this question for SSH).
linux networking services protocols
asked 8 hours ago
sixty4bitsixty4bit
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I'm reading a book on network programming with Go. One of the chapters deals with the /etc/services file. Something I noticed while exploring this file is that certain popular entries like HTTP and SSH, both of which use TCP at the transport layer, have a second entry for UDP. For example on Ubuntu 14.04:
ubuntu@vm1:~$ grep ssh /etc/services
ssh 22/tcp # SSH Remote Login Protocol
ssh 22/udp
ubuntu@vm1:~$ grep http /etc/services
http 80/tcp www # WorldWideWeb HTTP
http 80/udp # HyperText Transfer Protocol
Anyone know why these have two entries? I don't believe SSH or HTTP ever use UDP (confirmed by this question for SSH).
linux networking services protocols
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
2
22/udpwas removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?
– Stéphane Chazelas
8 hours ago
2
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago
add a comment
|
I'm reading a book on network programming with Go. One of the chapters deals with the /etc/services file. Something I noticed while exploring this file is that certain popular entries like HTTP and SSH, both of which use TCP at the transport layer, have a second entry for UDP. For example on Ubuntu 14.04:
ubuntu@vm1:~$ grep ssh /etc/services
ssh 22/tcp # SSH Remote Login Protocol
ssh 22/udp
ubuntu@vm1:~$ grep http /etc/services
http 80/tcp www # WorldWideWeb HTTP
http 80/udp # HyperText Transfer Protocol
Anyone know why these have two entries? I don't believe SSH or HTTP ever use UDP (confirmed by this question for SSH).
linux networking services protocols
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm reading a book on network programming with Go. One of the chapters deals with the /etc/services file. Something I noticed while exploring this file is that certain popular entries like HTTP and SSH, both of which use TCP at the transport layer, have a second entry for UDP. For example on Ubuntu 14.04:
ubuntu@vm1:~$ grep ssh /etc/services
ssh 22/tcp # SSH Remote Login Protocol
ssh 22/udp
ubuntu@vm1:~$ grep http /etc/services
http 80/tcp www # WorldWideWeb HTTP
http 80/udp # HyperText Transfer Protocol
Anyone know why these have two entries? I don't believe SSH or HTTP ever use UDP (confirmed by this question for SSH).
linux networking services protocols
linux networking services protocols
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 5 hours ago
sixty4bit
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
asked 8 hours ago
sixty4bitsixty4bit
1335 bronze badges
1335 bronze badges
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
sixty4bit is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
2
22/udpwas removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?
– Stéphane Chazelas
8 hours ago
2
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago
add a comment
|
2
22/udpwas removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?
– Stéphane Chazelas
8 hours ago
2
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago
2
2
22/udp was removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?– Stéphane Chazelas
8 hours ago
22/udp was removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?– Stéphane Chazelas
8 hours ago
2
2
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago
add a comment
|
1 Answer
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Basically, it's because that was the tradition from way back when port numbers started being assigned through approximately 2011. See, for example, §7.1 “Past Principles” of RFC 6335. It's possible they will be un-alloced someday, of course, as they're a limited resource (only 1023 available, total).
And, by the way, HTTP/3 runs over UDP. Though it can use any UDP port, not just 80/443. So really those are still unused.
As far as Debian is concerned, its /etc/services already had 22/udp in 1.0 (buzz 1996).
It was however removed in this commit in 2016, first released in version 5.4 of the netbase package.
As of writing, the latest stable version of Debian (buster) has 5.6. And the latest Ubuntu LTS (18.04, bionic) netbase package is based on Debian 5.4 and you can see its changelog also mentions the removal of udp/22.
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
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I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
add a comment
|
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Basically, it's because that was the tradition from way back when port numbers started being assigned through approximately 2011. See, for example, §7.1 “Past Principles” of RFC 6335. It's possible they will be un-alloced someday, of course, as they're a limited resource (only 1023 available, total).
And, by the way, HTTP/3 runs over UDP. Though it can use any UDP port, not just 80/443. So really those are still unused.
As far as Debian is concerned, its /etc/services already had 22/udp in 1.0 (buzz 1996).
It was however removed in this commit in 2016, first released in version 5.4 of the netbase package.
As of writing, the latest stable version of Debian (buster) has 5.6. And the latest Ubuntu LTS (18.04, bionic) netbase package is based on Debian 5.4 and you can see its changelog also mentions the removal of udp/22.
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
add a comment
|
Basically, it's because that was the tradition from way back when port numbers started being assigned through approximately 2011. See, for example, §7.1 “Past Principles” of RFC 6335. It's possible they will be un-alloced someday, of course, as they're a limited resource (only 1023 available, total).
And, by the way, HTTP/3 runs over UDP. Though it can use any UDP port, not just 80/443. So really those are still unused.
As far as Debian is concerned, its /etc/services already had 22/udp in 1.0 (buzz 1996).
It was however removed in this commit in 2016, first released in version 5.4 of the netbase package.
As of writing, the latest stable version of Debian (buster) has 5.6. And the latest Ubuntu LTS (18.04, bionic) netbase package is based on Debian 5.4 and you can see its changelog also mentions the removal of udp/22.
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
add a comment
|
Basically, it's because that was the tradition from way back when port numbers started being assigned through approximately 2011. See, for example, §7.1 “Past Principles” of RFC 6335. It's possible they will be un-alloced someday, of course, as they're a limited resource (only 1023 available, total).
And, by the way, HTTP/3 runs over UDP. Though it can use any UDP port, not just 80/443. So really those are still unused.
As far as Debian is concerned, its /etc/services already had 22/udp in 1.0 (buzz 1996).
It was however removed in this commit in 2016, first released in version 5.4 of the netbase package.
As of writing, the latest stable version of Debian (buster) has 5.6. And the latest Ubuntu LTS (18.04, bionic) netbase package is based on Debian 5.4 and you can see its changelog also mentions the removal of udp/22.
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
Basically, it's because that was the tradition from way back when port numbers started being assigned through approximately 2011. See, for example, §7.1 “Past Principles” of RFC 6335. It's possible they will be un-alloced someday, of course, as they're a limited resource (only 1023 available, total).
And, by the way, HTTP/3 runs over UDP. Though it can use any UDP port, not just 80/443. So really those are still unused.
As far as Debian is concerned, its /etc/services already had 22/udp in 1.0 (buzz 1996).
It was however removed in this commit in 2016, first released in version 5.4 of the netbase package.
As of writing, the latest stable version of Debian (buster) has 5.6. And the latest Ubuntu LTS (18.04, bionic) netbase package is based on Debian 5.4 and you can see its changelog also mentions the removal of udp/22.
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
edited 7 hours ago
Stéphane Chazelas
336k58 gold badges655 silver badges1034 bronze badges
336k58 gold badges655 silver badges1034 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
answered 7 hours ago
derobertderobert
80.2k9 gold badges179 silver badges236 bronze badges
80.2k9 gold badges179 silver badges236 bronze badges
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
add a comment
|
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
I may be mistaken, but also has to do with firewalls often blocking UDP
– Sergiy Kolodyazhnyy
7 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
@SergiyKolodyazhnyy I'd think not, as this practice predates firewalls.
– derobert
5 hours ago
add a comment
|
sixty4bit is a new contributor. Be nice, and check out our Code of Conduct.
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2
22/udpwas removed in Debian in 2016. IANA still lists 22/udp and lists both udp and tcp for most protocols that are only usually implemented on either one of them. Could just be that it means 22 is reserved for ssh in case somebody wants to implement ssh over udp some day?– Stéphane Chazelas
8 hours ago
2
See also section 7.1 of rfc6335
– Stéphane Chazelas
7 hours ago