Tell about your experience working with network sniffers.

I have experience working with network sniffers, mainly with Wireshark and Fiddler (or similar tools for HTTP/S traffic, such as Charles Proxy).

I used sniffers to solve the following tasks:

• Network interaction debugging: Analyzing requests and responses between client and server to identify issues in data transmission, HTTP error codes, message formats.
• API testing: Checking the correctness of request parameters, headers, response bodies, and response statuses during REST/SOAP API testing.
• Performance analysis: Identifying slow requests, analyzing response times, checking the use of compression and caching.
• Security testing: Detecting transmission of confidential information in plain text (without SSL/TLS), identifying unauthorized access attempts.
• Understanding protocol operation: Detailed study of packet structures of various protocols (TCP, UDP, HTTP, HTTPS, etc.).
• Reproducing problems: Capturing network traffic at the moment of defect occurrence for subsequent analysis and providing accurate data to developers.

When working with HTTPS traffic, I used methods of intercepting SSL/TLS, such as installing a trusted proxy server certificate (Fiddler, Charles Proxy) or configuring the client/server to use a proxy.

I applied filters to narrow down the analysis to the necessary traffic (by IP address, port, protocol).

In automated testing, I did not directly use sniffers, but their application was extremely useful during the development and debugging of test scenarios, especially when testing integrations and microservices. API testing tools (Postman, Newman) often have built-in capabilities for viewing requests and responses, essentially serving as simplified sniffers for specific protocols.