Talking to Servers

Sometimes it can be useful to interact with servers by hand for troubleshooting or to verify a servers response to certain commands.

Talking to a web server

You can send a GET request to a web server to receive the home page.

Unix

printf "GET / HTTP/1.0\r\n\r\n" | pync host.example.com 80

Windows

Create a text file (http_get.txt) containing the following:

GET / HTTP/1.0

That’s a GET request line followed by a blank line.

The blank line tells the web server that you’re done sending the request and are now ready to receive a response.

Once you’ve created the http_get.txt file, you can then pipe it into pync’s stdin stream to receive the web page:

py -m pync -C host.example.com 80 < http_get.txt

The -C flag tells pync to replace all LF (\n) characters with a CRLF sequence (\r\n).

Python

# http_get.py
import pync
pync.run('host.example.com 80', input=b'GET / HTTP/1.0\r\n\r\n')

Talking to a mail server

You could also submit emails to Simple Mail Transfer Protocol (SMTP) servers.

Suppose you have a text file (email_template.txt):

HELO host.example.com
MAIL FROM: <user@host.example.com>
RCPT TO: <user2@host.example.com>
DATA
From: A tester <user@host.example.com>
To: <user2@host.example.com>
Date: date
Subject: a test message

Body of email.
.
QUIT

You could then send this template to the server like so:

Unix

pync -C smtp.example.com 25 < email_template.txt

Windows

py -m pync -C smtp.example.com 25 < email_template.txt

Python

# smtp.py
import pync
with open('email_template.txt', 'rb') as f:
    pync.run('-C smtp.example.com 25', stdin=f)

SMTP typically requires lines to be terminated with a carriage return (CR) line feed (LF) sequence (\r\n).

The -C flag tells pync to replace all LF characters (\n) with CRLF characters instead (\r\n).