What Does Your User Agent Say About You?


A user agent is a computer program representing a person, for example, a browser in a Web context.

Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.

Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.

The user agent string can be accessed with JavaScript on the client side using the navigator.userAgent property.

A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".


User Agent String

Browser Data

User Agent String In Wireshark

Earl Hamilton
• Tuesday, 20 October, 2020
• 9 min read

Like whether chrome of Firefox or what browser or script is used for connecting to internet services When a host is infected or otherwise compromised, security professionals need to quickly review packet captures (caps) of suspicious network traffic to identify affected hosts and users.

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This tutorial offers tips on how to gather that cap data using Wireshark, the widely used network protocol analysis tool. In most cases, alerts for suspicious activity are based on IP addresses.

If you have access to full packet capture of your network traffic, a cap retrieved on an internal IP address should reveal an associated MAC address and hostname. DHCP traffic can help identify hosts for almost any type of computer connected to your network.

Open the cap in Wireshark and filter on boot pas shown in Figure 1. Note : With Wireshark 3.0, you must use the search term DHCP instead of boot.

Select one of the frames that shows DHCP Request in the info column. Go to the frame details section and expand the line for Bootstrap Protocol (Request) as shown in Figure 2.

Expand the lines for Client Identifier and Host Name as indicated in Figure 3. Client Identifier details should reveal the MAC address assigned to 172.16.1[.

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With HTTP-based web browsing traffic from a Windows host, you can determine the operating system and browser. This cap is from an Android host using an internal IP address at

Since more websites are using HTTPS, this method of host identification can be difficult. However, for those lucky enough to find HTTP web-browsing traffic during their investigation, this method can provide more information about a host.

Go to the frame details section and expand lines as shown in Figure 13. You should find a user account name for Theresa.Johnson in traffic between the domain controller at 172.16.8[.

Using the methods from this tutorial, we can better utilize Wireshark to help us identify affected hosts and users. Capturing traffic with pump on Linux CentOS 5.7 machine running Apache HTTP and analyzing in Wireshark.

Rv: gecko version indicates the release version of Gecko (such as 17.0 “). For compatibility, it adds strings like HTML, like Gecko and Safari.

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The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/”. In this example, the useragentstring is mobile Safari’s version.

Regex to find the Unique Identifier field value: ({10}\-{4}\-{4}\-{4}\-{12}) Wireshark is an essential network analysis tool for network professionals.

It is used for network troubleshooting, software analysis, protocol development, and conducting network security review. In order to troubleshoot computer network related problems effectively and efficiently, an in-depth understanding of TCP/IP is absolutely necessary, but you also need to know how to use the Wireshark ’s features, so that you can save time and effort while you are troubleshooting.

* Tip: You can use English and C-like terms in the same way, they can even be mixed in a filter string. Table6.4. Display Filter comparison operators.

Pocketknife provide a nice cheat sheet for Wireshark Display Filter. A full list of Wireshark's display filters (Display Filter Reference) is available here.

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