Blog posts tagged with 'tips'
Rewrite
Performing content rewrite at milli-speed is key to providing a front-end device for application delivery. Most important is the capability to rewrite both request and response headers & body content which the Citrix Application Switch does and it is an easy 3-step process to configure. Not only is it easy, it scales to Enterprise class applications, which we demonstrated here with the Oracle Enterprise Business Suite v12 in our lab in Santa Clara, CA, USA.
This Content Rewrite Deployment Guide walks through the steps necessary to quickly profile an application and configure the Citrix Application Switch for content rewrite. This deployment guide can be used as a reference for other Enterprise applications, in addition to Oracle. Some typical examples of how customers use the Citrix Application Swtich for content rewrite are to Insert the Client-IP as an HTTP Header, Delete old X-Forwarded-For headers, Tag SSL and non-SSL Connections, Mask the HTTP server type (Server Obfuscation), Redirect external URLs to Internal URLs (Application Obfuscation), Migrate Apache rewrite module rules, Redirect marketing keyword requests, Redirect old home pages and Redirect queries to the appropriate server.
The Citrix Rewrite Deployment Guide.
Watch this Rewrite Tip:
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Read about the Citrix Application Switch here.
Buy the Citrix Application Switch here.
In the Application Expert series part 2, Caching, I released a Deployment Guide discussing Static and Dynamic Caching. As we are partners with Microsoft, we recently did some work here internally setting up some Dynamic Caching for an ASP.NET application and thought we would share the knowledge. This Caching Deployment Guide for ASP.NET Web Applications discusses the way an Application Expert would find out the potential caching scenarios that a web application can benefit from, and shows how to create and test the NetScaler caching policies and settings to put these scenarios into effect.
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And it's FREE! Throw away those behemoths that suck power from every grid in the state and drain your budget. This baby is Free, Open Source and VIRTUAL, meaning you can run as many instances of this router as you want on your choice of hardware. What is even more gratifying is it's faster than the old router technology.
Vyatta has commoditized router, firewall and VPN deployment in the same way that Linux commoditized the operating system market. Vyatta open-source networking offers you an alternative to over-priced, inflexible products from proprietary vendors.
Vyatta software enables customers to build routing and security solutions using standard x86-based hardware of their choosing, ensuring networks will always meet performance requirements. Vyatta open-source software delivers the unique advantage of allowing customers to scale networks from the simplest LAN configurations to large BGP WAN edge configurations using a single software package.
Vyatta software includes support for most commonly used network interfaces, industry standard routing and management protocols, and all of these features are configurable via a single command-line interface (CLI) or web-based graphical user interface (GUI) - avail Q3'08. The integrated features and functionality make Vyatta software ideal for SMB, Branch Office, Enterprise and Service Provider deployments.
Summary of features:
BGP, OSPF, RIP, DHCP, QoS, IPSec VPN, VRRP, PPP, 802.1Q, Complete List.
This open source router is already running on XenServer in a large service provider in Europe. We are using it in our Citrix Ready program as a multi-link Intranet with connections to the Internet along with high availability link load balancing.
This para-virtualized Vyatta image runs as a virtual appliance in XenServer v3.2.1 and v4.1.
The XenServer Platform we are using:
- Dell Poweredge 2950 server.
- 2 x Intel 64-bit Quad-Core Xeon Processors, Model E5335 @ 2.00 GHz each, for a total of 8 CPUs.
- 2 Intel 82571EB Gigabit Ethernet (on-board)
- 2 Broadcom NetXtremeII Gigabit Ethernet
- 16 GB of memory.
- 300 GB of Storage.
- XenServer v4.1
- *note: CPU's must support virtualization technology.
Virtual Router - Install:
Virtual Router - Config:
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Application Delivery is at the top of the list of any organization's priorities. Keeping up with those priorities requires a move to dynamic application delivery and virtualization. The Citrix NetScaler Application Switch is a powerful step in that direction.
Compressing content at the server level can be done, but is tedious, and with the number of hosted servers on the backend growing proportionally with virtualization, it is better suited to a frontend tool.
As an Application Expert, determining what type of content is compressible vs. that which is not compressible should be at the tip of your tongue, or at least you should be able to reference this post or document. The thing is, while some content types remain compressible/non-compressible across many applications, you might run across an application that requires some content be treated uniquely. For example, the SAP application requires that pdf files should not be compressed when sent back to the clients. Either way, you should know how to dynamically configure rules to accommodate for the applications content. This Compression Deployment Guide shows you how.
Watch this Compression Tip:
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Hundreds of Thousands of Web Servers have been getting hacked, including several at the United Nations. The appearance is that the hack exploits a vulnerability in Microsoft IIS because of a Microsoft SQL Specific injection payload, however the attack is capable of infecting any type of web server open to SQL Injection and Cross Site Scriting (XSS) attacks.
Microsoft released some security bulletins (951306, MS08-006) stating vulnerabilities in their IIS web server, alluding to the vulnerabilities recently brought to light. A script homed at nihaorr1.com based in China was found to be infecting many servers, and spreading quickly. Further research into the problem indicates that non-Microsoft types of servers may also be affected by the attack.
As of May 12, 2008, Google's Index had 1,700,000 infected pages. The domains currently being injected that contain the malicious Javascript are:
- nihaorr1.com
- 2117966.net
- aspder.com
- haoliuliang.net
- nmidahena.com
- free.hostpinoy.info
- xprmn4u.info
- winzipices.cn
- wowgm1.cn
- killwow1.cn
- wowyeye.cn
- wowgm1.cn
- winzipices.cn
This vulnerability and others like it can easily be stopped with a Citrix Web Application Firewall using default policies to block SQL injection and Cross Site Scripting. We setup a demo in our lab, to show how easy it is to configure and block this type of threat.
See the mailicious script in action:
Watch how Citrix Web App Firewall blocks the malicious script:
See how easy it is to configure the Citrix Web App Firewall:
Read about the Citrix Application Firewall here.
Buy the Citrix Application Firewall here.
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As an addendum to the Citrix NetScaler Policy Engine post I wrote recently, I pulled together some Frequently Asked Questions (FAQ) pertaining to the Policy Engine (PE). Policies are used to configure various Citrix NetScaler Application Switch features, and are executed in the order of their priorities. The priorities are configurable and increment in units of 10.
Watch this Policy Priority Tip:
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Policies are used to configure various Citrix NetScaler Application Switch features. For example, the parameters for compressing content are defined in a compression policy.
The features that use policies are:
- Load Balancing
- Content Switching
- Content Filtering
- AppCompress
- Cache Redirection
- SSL VPN
- Priority Queuing
- DoS Protection
- Sure Connect
Policy expressions are applied to content that enters the switch. Expressions are shared among features, but actions are feature-specific. For example, you can create an expression to identify .pdf files being sent through the system. You can then create a compression policy that uses this expression to compress those files. The Policy Engine (PE) refers to the architecture in the Citrix NetScaler Application Switch for versions up to 8.x. The architecture for Policy Engine and the manner in which it operates is presented in this Deployment Guide. Did you know that each feature in the Citrix NetScaler Application Switch is processed in a certain order, and the Policy Engine (PE) applies policy according to that order. That order is represented in this diagram and discussed in the Deployment Guide for Policy Engine (PE).
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As web applications grow in complexity, the art of accelerating them seems to remain the same. This art is performed by applying some basic concepts to the application; that is, Caching, Compression, Load Balancing, Global Server Load Balancing, SSL Offload & Acceleration, Content Switching, TCP Multiplexing and SSL Session Reuse.
Citrix® is a leader in Gartners magic quadrant for Application Delivery with their flagship appliance NetScaler®. NetScaler accelerates web application performance by leveraging multiple acceleration technologies and innovative TCP optimizations.
Whether you are building out a new datacenter and architecting it the right way, or retrofitting an existing datacenter, Citrix NetScaler will perform and keep costs down. Whether you are looking to accelerate legacy enterprise applications such as Oracle or SAP, or building a new web 2.0 social community, Citrix NetScaler contains all of the tools to get you there.
Citrix NetScaler web application delivery solutions are purpose built appliances that accelerate application performance, while simultaneously reducing datacenter costs and improving web application security. Platforms range from the entry level 7000 to the latest MPX-series appliances that provide an industry-leading 15 Gbs of throughput at Layers 4 through 7.
There's more here: Case Studies, White Papers, Analysts , Datasheets
Check out the new MPX!
Buy it here!
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Becoming an Application Expert means that you can profile an application and quickly determine how it can be architected or re-constructed for higher performance. Of course, we want you to use the Citrix Application Switch as part of the architecture. In Part 1, we learned how to profile an application to learn what it looks like as the traffic flows through the Citrix Application Switch. Now we will determine what parts of an application are cacheable and what parts are non-cacheable.
By Application Profiling we can determine which parts of the application are cacheable and non-cacheable just by looking at the Request and Response headers. The application will sometimes tell you through it's "Cache-Control" header directives. Some content that we just know is static and doesn't ever change, we can consider cacheable as static content. Content that changes, such as reports, are often considered non-cacheable but with the help of Selectors and Dynamic Content Groups in the Citrix NetScaler, this content can be cached. As a proof of concept, we deployed the Citrix NetScaler Application Switch in the front of Oracle E-Business Suite v12 application and implemented caching policies for both static and dynamic content. As it turns out, alot of static content is cached by default policies and setting up dynamic policies is not that difficult. To see how, read the Caching Deployment Guide for Oracle E-Business Suite v12.
Watch this Caching Tip:
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Application Profiling
Introduction:
I can turn you into an Application expert in 5 minutes by reading this post. Just do what the experts do, or even the not-so-experts. They pay meticulous attention to the requests from clients and the responses from servers, both headers and body content. You do this the old fashioned way by taking a trace. There are better tools out there, some free, some not-so-free.
Running a trace:
Running a trace will help you 'profile' the application. It is recommended that you do this before placing the Citrix Application Switch in-line of the Application traffic. This will gather important information about the Application that will help you understand it's basic operation at Layer 7, and help you begin to understand what it is that needs to be accelerated - cached, compressed, load balanced, ssl offloaded, etc.
Running a trace exposes the flow of transactions between all points of interest. Traces are especially helpful when digging in to find what is contained within the headers being exchanged between the client and the application.
Taking a trace with wireshark:
The free network protocol analyzer called wireshark, http://www.wireshark.org, will capture packets for you on the localhost, whether it's windows or linux. By filtering the stream of packets by IP Address, right clicking and selecting 'Follow TCP Stream' inside of wireshark, you can see the headers for both requests and responses.
 | Wireshark tip 1 Find the first 'SYN' in the stream, right click, 'Follow TCP Stream'. |
| Wireshark tip 2 Client requests are in Red, Server responses are in Blue. |
Taking a trace with the Citrix Application Switch:
If the Citrix Application Switch is already in place, a trace can be run directly on the Citrix Application Switch. Running a trace will expose the flow of transactions between all points of interest, especially the client, load balancing VIPs and backend servers. Traces are especially helpful when digging in to find out if the proper headers are being exchanged between client & VIP and VIP & backend servers. A trace can be run directly on the Citrix Application Switch. Once downloaded this file can be opened and request and response headers read with Wireshark, a free network trace utility, http://www.wireshark.org. From the Citrix Application Switch GUI, navigate to NetScaler -> System -> Diagnostics -> New Trace -> Run.
Viewing headers with Paros:
Paros was originially written for web security, but has value when viewing request and response headers, cookies and the like. Through Paros's proxy nature, all HTTP and HTTPS data between server and client, including cookies and form fields, can be intercepted. There is an additional option of trapping and modifying data before sending it on to the server, or client. Paros can be found at http://parosproxy.org. Free.
Viewing headers with Live HTTP Headers:
Live HTTP Headers, http://livehttpheaders.mozdev.org/, was developed for use with the Firefox web browser. It is a free add-on and allows you to view HTTP header information in real time. Free.
Viewing headers with IE Analyzer:
IEInspector HTTP Analyzer, http://www.ieinspector.com, is a tool that allows you to monitor, trace, debug and analyze HTTP/HTTPS traffic in real-time. It works with Microsoft Internet Explorer. Not-Free.
Viewing headers with IE Watch:
IEWatch, http://www.iewatch.com, is another plug-in for Microsoft Internet Explorer that helps you profile your web applications. You can use this tool to dig deep into the inner workings of web applications to find hidden issues. Not-Free.
Watch this Application Profiling Tip:
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