How to send an HTTP request using Telnet [closed]

问题:

How to get web page's content using Telnet? (for example https://stackoverflow.com/questions page's content)

回答1:

telnet ServerName 80

---

GET /index.html

回答2:

You could do

telnet stackoverflow.com 80

And then paste

GET /questions HTTP/1.0
Host: stackoverflow.com


# add the 2 empty lines above but not this one

Here is a transcript

$ telnet stackoverflow.com 80
Trying 151.101.65.69...
Connected to stackoverflow.com.
Escape character is '^]'.
GET /questions HTTP/1.0
Host: stackoverflow.com

HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
...

回答3:

For posterity, your question was how to send an http request to https://stackoverflow.com/questions. The real answer is: you cannot with telnet, cause this is an https-only reachable url.

So, you might want to use openssl instead of telnet, like this for instance

$ openssl s_client -connect stackoverflow.com:443
...
---
GET /questions HTTP/1.1
Host: stackoverflow.com

This will give you the https response.

回答4:

To somewhat expand on earlier answers, there are a few complications.

telnet is not particularly scriptable; you might prefer to use nc (aka netcat) instead, which handles non-terminal input and signals better.

Also, unlike telnet, nc actually allows SSL (and so https instead of http traffic -- you need port 443 instead of port 80 then).

There is a difference between HTTP 1.0 and 1.1. The recent version of the protocol requires the Host: header to be included in the request on a separate line after the POST or GET line, and to be followed by an empty line to mark the end of the request headers.

The HTTP protocol requires carriage return / line feed line endings. Many servers are lenient about this, but some are not. You might want to use

printf "%\r\n" \
    "GET /questions HTTP/1.1" \
    "Host: stackoverflow.com" \
    "" |
nc --ssl stackoverflow.com 443

If you fall back to HTTP/1.0 you don't always need the Host: header, but many modern servers require the header anyway; if multiple sites are hosted on the same IP address, the server doesn't know from GET /foo HTTP/1.0 whether you mean http://site1.example.com/foo or http://site2.example.net/foo if those two sites are both hosted on the same server (in the absence of a Host: header, a HTTP 1.0 server might just default to a different site than the one you want, so you don't get the contents you wanted).

The HTTPS protocol is identical to HTTP in these details; the only real difference is in how the session is set up initially.