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Development Tools HTTP Basics Introduction to HTTP HTTP Requests Using Telnet

Posted by Luis Marsano
Luis Marsano
21,425 Points

Why use telnet instead of raw TCP?

Sysadmin/networking guides typically recommend netcat/ncat/socat or TCP device over telnet.

  • Telnet is not raw TCP: it does some character handling and can garble data.
  • Telnet clients are no longer included with modern OSs.
  • According to video, telnet input has a time constraint?
  • Telnet is for terminal sessions, not actually meant for raw communication.

In contrast

  • The recommended commands send data unaltered.
  • ncat is available on POSIX and Windows.
  • No additional time constraint.
  • General purpose network diagnostics: actually meant for raw communication.

equivalent bash script for TCP device

#!/bin/bash
{
    sed -e 's/$/\r/' <<EOF >&3
GET $uri HTTP/1.1
Host: $domain

EOF
    cat <&3
} 3<>/dev/tcp/$domain/http

equivalent netcat

nc -C $domain http <<EOF
GET $uri HTTP/1.1
Host: $domain

EOF