netcat
A featured networking utility which reads and writes data across network connections, using the TCP/IP protocol.
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