HTTP

IP

IP
IPv6

HTTP

1990    HTTP/0.9    GET only, no headers
1996    HTTP/1.0    Method, Headers, StatusCode, Redirect etc...
1997    HTTP/1.1    KeepAlive, TLS, Upgrade, Chunk ...
2015    HTTP/2      
2018    HTTP/3      udp:443

Protocol Negotiation

HTTP    TCP Handshake
HTTPS   HTTP + TLS Handshake
WS      HTTP Upgrade
WSS     HTTP Upgrade + TLS Handshake
H2      TCP Handshake + TLS-ALPN handshake
H2C     HTTP Upgrade, send HTTP2 Magic#(Preface)
H3      HTTP2 + Alt+Svc

SSL/TLS

SSL 1.0
    2.0
    3.0
TLS 1.0
    1.1
    1.2
    1.3

Cipher Suite

TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384   (old format < TLS 1.3)
TLS_AES_128_GCM_SHA256                  (new format)
... and lots

Status Code (61)

100     Continue
101     Switching Protocols
102     Processing  (deprecated)
103     Early Hints

200     OK
201     Created
202     Accepted
203     Non-Authoritative Information
204     No Content
205     Reset Content
206     Partial Content
207     Multi-Status
208     Already Reported
226     IM Used

300     Multiple Choices
301     Moved Permanently
302     Found
303     See Other
304     Not Modified
307     Temporary Redirect
308     Permanent Redirect

400     Bad Request
401     Unauthorized
402     Payment Required
403     Forbidden
404     Not Found
405     Method Not Allowed
406     Not Acceptable
407     Proxy Authentication Required
408     Request Timeout
409     Conflict
410     Gone
411     Length Required
412     Precondition Failed
413     Content Too Large
414     URI Too Long
415     Unsupported Media Type
416     Range Not Satisfiable
417     Expectation Failed
418     I'm a teapot
421     Misdirected Request
422     Unprocessable Content
423     Locked
424     Failed Dependency
425     Too Early
426     Upgrade Required
428     Precondition Required
429     Too Many Requests
431     Request Header Fields Too Large
451     Unavailable For Legal Reasons

500     Internal Server Error
501     Not Implemented
502     Bad Gateway
503     Service Unavailable
504     Gateway Timeout
505     HTTP Version Not Supported
506     Variant Also Negotiates
507     Insufficient Storage
508     Loop Detected
510     Not Extended
511     Network Authentication Required

Headers (106)

Accept                              Accept: application/json
Accept-CH
Accept-Charset                      Accept-Charset: utf-8
Accept-Encoding                     Accept-Encoding: gzip, deflate
Accept-Language                     Accept-Language: en-US, ja-JP
Accept-Patch
Accept-Post
Accept-Ranges
Access-Control-Allow-Credentials    ;; CORS
Access-Control-Allow-Headers        ;; CORS
Access-Control-Allow-Methods        ;; CORS
Access-Control-Allow-Origin         ;; CORS
Access-Control-Expose-Headers       ;; CORS
Access-Control-Max-Age          
Access-Control-Request-Headers
Access-Control-Request-Method
Age
Allow
Alt-Svc
Alt-Used
Authorization                       Authorization: Basic dXNlcjpwYXNz
Cache-Control                       Cache-Control: no-cache
Clear-Site-Data
Connection                      [h] Connection: Upgrade, close      ;; see HOP-BY-HOP
Content-Disposition
Content-Encoding
Content-Language
Content-Length
Content-Location
Content-Range
Content-Security-Policy
Content-Security-Policy-Report-Only
Content-Type
Cookie
Cross-Origin-Embedder-Policy
Cross-Origin-Opener-Policy
Cross-Origin-Resource-Policy
Date
Device-Memory
ETag
Expect
Expect-CT
Expires
Forwarded
From
Host                            [!] Host: example.com:80
If-Match
If-Modified-Since
If-None-Match
If-Range
If-Unmodified-Since
Keep-Alive                      [h]
Large-Allocation
Last-Modified
Link
Location
Max-Forwards
Origin
Permissions-Policy
Pragma
Deprecated
Proxy-Authenticate              [h]
Proxy-Authorization             [h]
Range
Referer
Referrer-Policy
Reporting-Endpoints
Retry-After
Sec-Fetch-Dest
Sec-Fetch-Mode
Sec-Fetch-Site
Sec-Fetch-User
Sec-Purpose
Sec-WebSocket-Accept
Server
Server-Timing
Service-Worker-Navigation-Preload
Set-Cookie
SourceMap
Strict-Transport-Security
TE                              [h]
Timing-Allow-Origin
Tk
Trailer                         [h]
Transfer-Encoding               [h]
Upgrade                         [h]
Upgrade-Insecure-Requests
User-Agent
Vary
Via
Viewport-Width
Want-Digest
Width
WWW-Authenticate
X-Content-Type-Options
X-DNS-Prefetch-Control
X-Forwarded-For
X-Forwarded-Host
X-Forwarded-Proto
X-Frame-Options
X-XSS-Protection

Hop-by-hop Headers (8+)

Connection     
Keep-Alive     
Proxy-Authenticate 
Proxy-Authorization
TE                 
Trailer            
Transfer-Encoding  
Upgrade         

RFC2616 hop-by-hop headers

"Hop-by-hop headers ... are meaningful only for a single transport-level connection, and are not stored by caches or forwarded by proxies"

Any hop-by-hop headers except "Connection" must be listed in the "Connection" header. Proxies will remove these.