Why wouldn’t you use curl for the quick test?

Sometimes you want to do something that curl cannot express, e.g. timing, protocol oddities, etc. For example you may want to issue a CONNECT to an echo server through a proxy and observe the bytes flowing back and forth. You may want to see what happens when conflicting hop-by-hop headers are specified without worrying about the client's (curl's) interpretation of them. A simple nc -c (or openssl s_client -crlf) lets you do all of that.

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asmnzxklopqw an hour ago | parent | prev | next [-]

Because curl is not installed in minimal docker images.

	▲	gear54rus an hour ago \| parent [-]
		neither is bash or even sh for that matter :) if you have bash, you probably have apk or apt

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a-dub 2 hours ago | parent | prev [-]

because in those days there was no curl, or wget. and then when there was, there was no guarantee they'd be installed.

telnet was always there though. it also worked for speaking all the other plaintext internet protocols. (imap, pop, smtp, etc)

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HeckFeck an hour ago | parent | next [-]

I used telnet to send mail via SMTP once, it's quite literally a good social protocol because it begins with a polite 'HELO'.

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a-dub an hour ago | parent [-]

the '90s version of finding the hiring manager or boss on linkedin to try and get a job was connecting to the company's public smtp server with telnet, using their name to probe different email address patterns with "rcpt to:" (those days the actual servers were often directly connected to the internet and would leak email address validity in how they would respond to rcpt to) and then sending them a nice email.

smtp grew up to be an antisocial curmudgeon. extended smtp starts with EHLO.

	▲	jolmg 15 minutes ago \| parent \| next [-]
		> smtp grew up to be an antisocial curmudgeon. extended smtp starts with EHLO. "EHLO" still sounds friendly. It just sounds like a different accent or something. Know someone that used to answer calls with a friendly "Jello?".
	▲	endofreach 38 minutes ago \| parent \| prev [-]
		> smtp grew up to be an antisocial curmudgeon. extended smtp starts with EHLO. email will become so unusable, next one will have to be HELNO i guess

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dragontamer 2 hours ago | parent | prev [-]

Note: Telnet is not completely plaintext and has control characters in the upper byte range (like 0xff or something, I forget).

Use nc or this TCP Bash technique if you really want to ensure decent compatibility when doing hacky solutions, otherwise a random 0xFF somewhere from a terminal console color change (or other control character) might really screw you over.

EDIT or ya know, use the correct tool like Curl.