netcat
A featured networking utility which reads and writes data across network connections, using the TCP/IP protocol.
https://netcat.sourceforge.net
Examples
Send HTTP request
The request was fetched with tcpdump.
1 cat request1.txt | nc 192.168.1.1 8080
Send SMTP request
The request was fetched with tcpdump.
ehlo example.com mail from: userx@example.com rcpt to: usery@example.net quit
1 cat requestsmtp1.txt | nc 192.168.1.1 25
Send hex string
http://unix.stackexchange.com/questions/82561/convert-a-hex-string-to-binary-and-send-with-netcat
- echo '0006303030304e43' | xxd -r -p | nc -l localhost 8181