I was reading documentation about HTTP/3, and in the article, they sed that they are no longer TLS or TCP. So it's mean that a web site with no SSL 80 will be changed to what port and 443 will be replaced with what port? Also how CA will make SSL UDP compatible?

  • Your question doesn't make sense. Ports are a feature of TCP. If HTTP/3 isn't going to use TCP, why would it use TCP ports? – Quentin Aug 2 at 16:16
  • Also the spec says it does use TLS. – Quentin Aug 2 at 16:17
  • 5
    HTTP/3 is build on top of QUIC which is using TLS 1.3 over UDP. – Steffen Ullrich Aug 2 at 17:09
  • 5
    @Quentin - Ports aren't just for TCP; UDP uses them too – paj28 Aug 2 at 19:19
  • I’m voting to close this question because it is based on a misreading of the source document. – schroeder Aug 3 at 7:23

HTTP/3 is HTTP over QUIC, which uses UDP packets (instead of HTTP over TCP pakcets). This makes packet loss less costly: instead of stalling all streams in the connection (HTTP/2 supports multiple streams), only the stream with packet lost gets affected.


HTTP/3 uses TLS1.3 over UDP (instead of TLS over TCP). Also, TLS1.3 has a feature called 0-RTT, which eliminates roundtrip for TLS hand-shaking to speed things up. So, TLS is becoming TLS1.3 (a major change though) and getting faster.



For HTTP/3, You'll continue be using the same ports (80 / 443) for the initial connection, but through the UDP ports instead of TCP ports. After the initial connection, you can then tell clients to use other UDP ports you preferred by providing alternate ports via alt-svc header and then the client will use any of the successful alternatives provided in that header.

https://tools.ietf.org/html/draft-ietf-quic-http-27 (see section 3.2)

https://blog.cloudflare.com/experiment-with-http-3-using-nginx-and-quiche/ (see the section "Running" for an example of supporting both both HTTP/2 and HTTP/3 at the same time)

About your last question: I'm not sure of your concern here. SSL has nothing to do with the port type. It's just a public-private key certificate scheme and can be used in many different purposes beyond securing HTTP and so it can surely be used with the newer protocols too.

https://help.one.com/hc/en-us/articles/115005594265-Can-I-use-SSL-with-my-email- (SSL being used for another purpose)

https://kinsta.com/knowledgebase/tls-vs-ssl/ (see summary section - if you have an SSL cert, you're covered for all, including TLS1.3)

| improve this answer | |

Not the answer you're looking for? Browse other questions tagged or ask your own question.