Ask Tony Archive

  • Web Application Firewall: What’s In A Name?

    Web Application Firewall: What’s In A Name?

    In my recent review of KEMP’s new LoadMaster software, which includes Web Application Firewall capabilities, Ofer Shezaf (from breach.com) had this to say in the comments section: Systems supporting only snort rules and lacking a positive security model are not usually not considered a web...

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  • Mega Proxy Not So Mega, Akshually

    Mega Proxy Not So Mega, Akshually

    Apologies for the LOLcatspeak.  I’m incapable of helping myself. The driving force behind Layer 7 persistence (keeping an individual user tied to a specific server in a server group based on HTTP headers instead of IP address) was the dreaded AOL Megaproxy issue.  AOL had...

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  • New Survey

    New Survey

    It’s been about 6 months since the last load balancing/application delivery survey, so I think it’s high time we did another one. So here’s your chance to contribute to the questions:  What do you want to know?  Put your suggestions in the comments section below,...

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  • Cisco CSS Replacements

    Cisco CSS Replacements

    There was a post today on the lb-l mailing list asking about alternatives to Cisco’s CSS. This is part of a trend I’ve noticed lately, where people who have an existing Cisco CSS installation are looking to replace that gear with new gear. Cisco CSS...

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  • Troubleshoot Any Load Balancing Ailment: End-to-End Connectivity

    Troubleshoot Any Load Balancing Ailment: End-to-End Connectivity

    You’re stumped. There’s a problem with your infrastructure, and you’re not positive what it is. You checked a few things out, but the symptoms befuddle you. You’re pretty sure it’s not the load balancer, but everyone is pointing at you, and you’ve got no proof....

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  • Think You’re Connected?  Think Again

    Think You’re Connected? Think Again

    One issue that trips up people when diagnosing load balancer problems is they see a connection has been made to a virtual service, so it looks like they’re getting through to the real server. That’s not always the case. Depending on how your load balancer...

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  • BIG-IP V4 Test Script

    BIG-IP V4 Test Script

    When I’m diagnosing load balancing issues, there are three really critical tools I use: TCPDump HTTP Header dump (such as Live HTTP Headers) Telnet Yup, telnet. I don’t know about anyone else, but I use telnet excessively. Basically, I use it to test TCP connectivity,...

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  • What Application Developers Need To Know About Load Balancers

    What Application Developers Need To Know About Load Balancers

    You’re an application developer. You work in a world of untyped variables, debugging, and hitting reload over, and over, and over, and over again, all in the name of churning out a good web app. You can spot a SQL syntax error from the corner...

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  • PHP and Load Balancers

    PHP and Load Balancers

    I got this email today from Don Keller in New Orleans regarding PHP interacting with a load balancer: I read somewhere that the load balancer you run must support sessions, otherwise you must use cookies.” This is a common type of question that people who...

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  • How To Choose A Load Balancer

    How To Choose A Load Balancer

    I get a lot of questions on what’s the best load balancer to choose. There are currently over 20 vendors too choose from, so buyers can experience a little bit of over-choice shutdown. So, here’s a few tips to help whittle down the vendors. The...

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