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Increasing number of concurrent connections




Posted by IPconnect, 04-03-2016, 07:50 PM
Hello, I am trying to run Xenu Link Sleuth on my web site to check for broken links. The software requires many concurrent connections (don't know the exact amount) due to the way it crawls the web site to check for broken links simultaneously. When I run the tool, it works for a short while but then it begins generating "timeout" messages due to the server blocking the traffic. The server perceives the number of connections as a threat even though none exists. I have used the software on my other web sites for years without any issues. Given that this is server/security related, I am hoping to get advice on how I can help my web host fix this problem. I am a front end web developer so this isn't really my specialty, but how can we configure the server to allow more concurrent connections? i.e. is there a recommended limit? Alternatively, is it possible to allow an unlimited number of concurrent connections from a specific (safe) IP address? Thank you.

Posted by UNIXy, 04-04-2016, 06:56 AM
This likely means that your Web host limits the number of simultaenous connections it can receive at once. And that's OK if you're on shared hosting (host is protecting the whole server). I'm not familiar with Xenu Link Sleuth but can't you limit the number of connections? Lower it down a bit so the server doesn't throttle things down. If you're hosting your site on VPS or dedicated, you'll need to dig down deeper in the error logs to identify the culprit.

Posted by IPconnect, 04-04-2016, 09:14 AM
Thanks for the response. I can lower the number of connections in the software, but the problem is that it adds significant processing time to complete the broken link report. I did some calculations and it would take 100+ hours to get the full report by reducing the thread count. Here is what I would like to do: the software runs fine on one of my two servers. How would I go about finding out the number of concurrent connections allowed by the one server where it runs perfectly? Based on that, I will ask my other web host to configure their server to allow the same number of concurrent connections.

Posted by BeZazz, 04-04-2016, 10:50 AM
The only thing you can do is talk to both hosts.

Posted by UNIXy, 04-05-2016, 06:38 AM
It could be a number of places you'll need to check. But here's a quick list: * Firewall: Look for rate limiting or DoS mitigation rules * Web server (ex: Apache, look for MaxClients in httpd.conf or CloudLinux's lve) * Modsecurity: rate limiting rules Good luck! Cheers



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