Posted 8 April, 2015 by in SEO

How To Use Wireshark With The SEO Spider

Here at Screaming Frog we occasionally get support queries from users of the SEO Spider reporting issues such as recording the wrong response code, or perhaps reporting a page to have no title or headings, when they are there when viewed in a browser. We often get asked if it’s bug in the software, but sometimes sites just respond differently depending on User-Agent, whether cookies are accepted, or if the server is under load for example.

Would it not be great if there was an easy way to independently verify what was being reported by the SEO Spider?

Well, actually there is. Enter Wireshark the worlds leading network protocol analyser. It captures and logs network traffic, allowing you to inspect packets sent and received by your computer. It’s available, for free, on all major operating systems and I wanted to put a guide together to show SEOs how Wireshark can be extremely useful verifying data (and a lot more!).

To show how to use Wireshark, I have created a page here that will not include a page title element if the requesting User-Agent contains the word ‘Spider’. The demo page doesn’t contain any links, but if you were doing this on a real site it would be worth limiting the crawl to just a single URL to minimise the amount of traffic generated (Configuration -> Spider and set ‘Limit Search Total’ to ‘1’ in the Limits tab).

Now start up Wireshark and choose Capture-> Start from the menu:


Switch back to the SEO Spider and start the crawl of the page. Once this is complete, switch back to Wireshark and choose Capture-> Stop.


In the filter input box at the top, type “http” and press enter.


This will filter out a lot of the traffic, ideally leaving you only with the HTTP traffic generated by the SEO Spider. Other browser sessions with active content or applications such as Dropbox will also generate HTTP traffic that may also be shown. You should be able to see a row in the master view with an ‘Info’ column containing:

GET /demo/missing_page_title/ HTTP/1.1

This is the request sent by the SEO Spider, you can inspect the contents of this by clicking the row and then expanding the “Hypertext Transfer Protocol” section in the details view:


Here we can view the HTTP request headers sent by the SEO Spider. Now, switch back to the main ‘master view’ again and within the next few packets, depending on what other HTTP traffic was captured, you’ll be able to see a packet with Info:

HTTP/1.1 200 OK (text/html)

This is the HTTP response. Again clicking on it allows us to view in more detail:

seo spider http response with wireshark

Here we can see the complete HTML returned under ‘Line-based text data: text/html’, and clearly see that it’s missing a page title.

If we now repeat the process by changing the User-Agent configured in the SEO Spider (Configuration-> User Agent) to GoogleBot regular.


Then re-run the capture, we can see the updated request:


And the corresponding response, now including the page title “I am scared of spiders!”.


There are other tools such as Web Sniffer that allow you to switch User-Agent and view the raw HTML returned, but they don’t capture exactly what’s happening like Wireshark which allows you to sniff any tool you might be using or building yourself.

Hopefully this post has been a useful insight into the role Wireshark can play in an SEO’s toolkit.