H2Nas01NginxMarkdown

§2024-11-05

socat

What is socat?

socat stands for SOcket CAT. It is a utility for data transfer between two addresses.

What makes socat so versatile is the fact that an address can represent a network socket, any file descriptor, a Unix domain datagram or stream socket, TCP and UDP (over both IPv4 and IPv6), SOCKS 4/4a over IPv4/IPv6, SCTP, PTY, datagram and stream sockets, named and unnamed pipes, raw IP sockets, OpenSSL, or on Linux even any arbitrary network device.

ubunt installation

sudo apt install socat

Usage

socat [options] <address1> <address2>

address1 is the source
address2 is the destination address
socat -d -d - TCP4:www.example.com:80
- -d -d options
- - first addres `
- TCP4:www.example.com:80 second address

example

if you have nginx running on localhost:80

$ curl localhost:80
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

then run on terminal 1

# socat -v TCP4-LISTEN:8080,fork TCP4:localhost:80

then from terminal 2

$ curl localhost:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

then on terminal 1

# socat -v TCP4-LISTEN:8080,fork TCP4:localhost:80
> 2024/11/05 08:09:50.000182890  length=77 from=0 to=76
GET / HTTP/1.1\r
Host: localhost:8080\r
User-Agent: curl/8.5.0\r
Accept: */*\r
\r
< 2024/11/05 08:09:50.000183684  length=862 from=0 to=861
HTTP/1.1 200 OK\r
Server: nginx/1.24.0 (Ubuntu)\r
Date: Tue, 05 Nov 2024 00:09:50 GMT\r
Content-Type: text/html\r
Content-Length: 615\r
Last-Modified: Mon, 04 Nov 2024 05:46:38 GMT\r
Connection: keep-alive\r
ETag: "67285fbe-267"\r
Accept-Ranges: bytes\r
\r
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>


4. example

$ echo -e "GET / HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n" | socat - TCP:localhost:80 HTTP/1.1 200 OK Server: nginx/1.24.0 (Ubuntu) Date: Mon, 04 Nov 2024 21:59:44 GMT Content-Type: text/html Content-Length: 615 Last-Modified: Mon, 04 Nov 2024 05:46:38 GMT Connection: close ETag: "67285fbe-267" Accept-Ranges: bytes

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