Protocol codes
Information and error codes for protocols (from the RFCs).
HTTP (1.1)
(From RFC 2616)
| Reply code | Suggested reason phrase |
| 100 | Continue |
| 101 | Switching Protocols |
| 200 | OK |
| 201 | Created |
| 202 | Accepted |
| 203 | Non-Authoritative Information |
| 204 | No Content |
| 205 | Reset Content |
| 206 | Partial Content |
| 300 | Multiple Choices |
| 301 | Moved Permanently |
| 302 | Found |
| 303 | See Other |
| 304 | Not Modified |
| 305 | Use Proxy |
| 307 | Temporary 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 Time-out |
| 409 | Conflict |
| 410 | Gone |
| 411 | Length Required |
| 412 | Precondition Failed |
| 413 | Request Entity Too Large |
| 414 | Request-URI Too Large |
| 415 | Unsupported Media Type |
| 416 | Requested range not satisfiable |
| 417 | Expectation Failed |
| 500 | Internal Server Error |
| 501 | Not Implemented |
| 502 | Bad Gateway |
| 503 | Service Unavailable |
| 504 | Gateway Time-out |
| 505 | HTTP Version not supported |
SMTP
(From RFC 2821)
| Reply code | Suggested reason phrase |
| 211 | System status, or system help reply |
| 214 | Help message |
| 220 | <domain> Service ready |
| 221 | <domain> Service closing transmission channel |
| 250 | Requested mail action okay, completed |
| 251 | User not local; will forward to <forward-path> |
| 252 | Cannot VRFY user, but will accept message and attempt delivery |
| 354 | Start mail input; end with <CRLF>.<CRLF> |
| 421 | <domain> Service not available, closing transmission channel |
| 450 | Requested mail action not taken: mailbox unavailable |
| 451 | Requested action aborted: local error in processing |
| 452 | Requested action not taken: insufficient system storage |
| 500 | Syntax error, command unrecognized |
| 501 | Syntax error in parameters or arguments |
| 502 | Command not implemented |
| 503 | Bad sequence of commands |
| 504 | Command parameter not implemented |
| 550 | Requested action not taken: mailbox unavailable |
| 551 | User not local; please try <forward-path> |
| 552 | Requested mail action aborted: exceeded storage allocation |
| 553 | Requested action not taken: mailbox name not allowed |
| 554 | Transaction failed |
Port numbers
A small selection of the most commonly used port numbers
| Keyword | Decimal | Description |
| ftp-data | 20/tcp | File Transfer [Default Data] |
| ftp | 21/tcp | File Transfer [Control] |
| ssh | 22/tcp | SSH Remote Login Protocol |
| smtp | 25/tcp | Simple Mail Transfer |
| nicname | 43/tcp | Who Is |
| domain | 53/tcp | Domain Name Server |
| domain | 53/udp | Domain Name Server |
| bootps | 67/udp | Bootstrap Protocol Server |
| bootpc | 68/udp | Bootstrap Protocol Client |
| http | 80/tcp | World Wide Web HTTP |
| pop3 | 110/tcp | Post Office Protocol - Version 3 |
| nntp | 119/tcp | Network News Transfer Protocol |
| ntp | 123/udp | Network Time Protocol |
| imap | 143/tcp | Internet Message Access Protocol |
| https | 443/tcp | http protocol over TLS/SSL |
| nntps | 563/tcp | nntp protocol over TLS/SSL (was snntp) |
| ftps-data | 989/tcp | ftp protocol, data, over TLS/SSL |
| ftps | 990/tcp | ftp protocol, control, over TLS/SSL |
| imaps | 993/tcp | imap4 protocol over TLS/SSL |
| pop3s | 995/tcp | pop3 protocol over TLS/SSL (was spop3) |
| cvspserver | 2401/tcp | cvspserver |
| mysql | 3306/tcp | MySQL |
| svn | 3690/tcp | Subversion |
| git | 9418/tcp | git pack transfer service |