How to use the command 'tcpflow' (with examples)
- Linux
- December 25, 2023
The ’tcpflow’ command is used to capture TCP traffic for debugging and analysis purposes. It allows users to monitor data flowing over a given interface and port. This can be useful for troubleshooting network issues, analyzing network protocols, or inspecting data packets for security purposes.
Use case 1: Show all data on the given interface and port
Code:
tcpflow -c -i eth0 port 80
Motivation:
When troubleshooting network issues, it can be helpful to monitor all TCP traffic on a specific interface and port. By using the ’tcpflow’ command with the ‘-c’ option, we can capture and display all the data flowing through that interface and port.
Explanation:
-c: This option tells tcpflow to display the captured data.-i eth0: This option sets the network interface as eth0, specifying the interface on which we want to capture traffic.port 80: This argument specifies the port number (in this case, port 80) on which we want to capture traffic.
Example output:
Capturing TCP traffic on interface eth0, port 80...
----------------------------------------
GET /index.html HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Upgrade-Insecure-Requests: 1
----------------------------------------
HTTP/1.1 200 OK
Date: Tue, 15 Sep 2020 14:00:00 GMT
Server: Apache
Content-Length: 1270
Content-Type: text/html; charset=UTF-8
<!DOCTYPE html>
<html>
<head>
<title>Welcome to Example.com</title>
</head>
<body>
<h1>Welcome to Example.com</h1>
<p>This is a sample webpage.</p>
</body>
</html>
In this example, tcpflow captures the TCP traffic on interface eth0 and port 80. It displays the captured data, including both the HTTP request sent by the client and the corresponding server response.
