isc Home | SANS Internet Storm Center; Cooperative Network Security Community - Internet Security Grid energy storage Simplified electrical grid with energy storage. Simplified grid energy flow with and without idealized energy storage for the course of one day. As of March 2012, pumped-storage hydroelectricity (PSH) is the largest-capacity form of grid energy storage available; the Electric Power Research Institute (EPRI) reports that PSH accounts for more than 99% of bulk storage capacity worldwide, around 127,000 MW. PSH energy efficiency varies in practice between 70% to 75%. An alternate approach to achieve the same effect as grid energy storage is to use a smart grid communication infrastructure to enable Demand response (DR). The core effect of both of these technologies is to shift energy usage and production on the grid from one time to another. Forms Air Compressed air 60 - 90% efficient Another grid energy storage method is to use off-peak or renewably generated electricity to compress air, which is usually stored in an old mine or some other kind of geological feature.
Using suphp To Secure A Shared Server The challenge with securing a shared hosting server is how to secure the website from attack both from the outside and from the inside. PHP has built-in features to help, but ultimately it s the wrong place to address the problem. Apache has built-in features too, but the performance cost of these features is prohibitive. This has created a gap that a number of third-party solutions have attempted to fill. One of the oldest of these is suphp, created by Sebastian Marsching. suphp: Running PHP As A Specified UserInstalling suphpConfiguring ApacheSome BenchmarksOther ConsiderationsConclusions suphp: Running PHP As A Specified User Like Apache’s own suexec, suphp is a solution that allows PHP to run as the user and group that owns any particular website on a shared hosting server. suphp consists of two components: mod_suphp, an Apache module that replaces mod_phpsuphp, a setuid binary that replaces Apache’s suexec It relies on PHP/CGI having been installed onto the server first. Installing suphp
Forget batteries: future devices could store power in wires Batteries have always been one of the biggest problems when developing small lightweight electronic devices. They're big and bulky, taking up a serious chunk of the real estate inside your smartphone or tablet. So imagine if they could be dispensed with, and replaced by a new type of internal wiring that can actually store power inside the body of the wire itself. That's the goal of a team of nanotechnology researchers at the University of Central Florida in Orlando. Professor Jayan Thomas and Ph.D. student Zenan Yu have developed a way to cover copper wires with a sheath made from alloy nanowhiskers, which then become one of the two electrodes needed to create a supercapacitor. Dr. University of Central Florida, via Treehugger
Community Help | Generating a Certificate Signing Requ... To complete your online request form for an SSL, you need to generat a key pair and a Certificate Signing Request (CSR). Follow these instructions to generate them for your website. Java 2 SDK 1.2 or above must be installed before you can generate your CSR. Once installed, you can use the "keytool" command to create your key pair and CSR. To Generate the Key Pair For the purposes of this article, we are using PuTTY as our Secure Shell (SSH) client, and we are running Tomcat on a Linux based server. To log in to the server's terminal SSH, double click on your servers SSH client.Enter the Host Name (or IP address), and then the Port the server is using.Select SSH as the Connection type, and then click OpenAt the SSH prompt, enter the server's username, and then press Enter on your keyboard.Enter the server's password, and then press Enter. To Generate a CSR For more information on how to request a certificate in our online request form, see Request an SSL certificate
Community Help | SSL Certificate Renewal - Tomcat 4.x/... After we approve your certificate renewal request, you can download your SSL and intermediate certificate. For more information, see Downloading an SSL Certificate. You must install both files on your Web server. You can also download the intermediate certificate here. Follow the instructions below to download and install signed certificate and intermediate certificates on your Web server. Note that Java 2 SDK 1.2 or above must be installed as the following describes how to install a certificate using keytool. Installation Option One: Installing SSL Certificate and CA Bundle (gd_bundle.crt) Implementing a PKCS12 Keystore Before you install your SSL certificate you must download our root certificate bundle (repository. Use the following OpenSSL command to combine the ca bundle (gd_bundle.crt) and your SSL certificate: openssl pkcs12 -export -chain -CAfile gd_bundle.crt -in Updating the server.xml Configuration File Open the server.xml file. Restart Tomcat. Root: Installing SSL Certificate
Community Help | Installing an SSL Certificate in Tomc... When you request an SSL certificate, you must provide a Certificate Signing Request (CSR) from your server. The CSR includes your public key, and must contain the same details as the online request form in your account. After your request is vetted and your certificate is issued, download and install all of the provided files to complete the installation. These steps describe how to install a certificate using keytool, so you must have Java 2 SDK 1.2 or above installed on your server. Generating a Keystore and CSR in Tomcat Using Keytool, follow these steps to generate a keystore and CSR on your server. To Generate a Keystore and CSR in Tomcat Enter the following command into keytool to create a keystore:keytool -keysize 2048 -genkey -alias tomcat -keyalg RSA -keystore tomcat.keystoreEnter a Password. For more information about completing the online request form, see Request an SSL certificate. After you submit the application, we begin vetting your request. Installing Your SSL in Tomcat
Troubleshooting Memory and Networking Issues Many common issues with Linodes are caused by excessive memory consumption or networking configuration errors. This guide provides suggestions for alleviating these problems. When your VPS is running low on physical memory, it may start to "swap thrash." This means it's attempting to use your swap partition heavily instead of real RAM. We recommend you limit your swap partition size to 256 MB; heavy use of swap in a virtualized environment will cause major performance problems. Determining Free Memory and Swap Activity You can use the following command to display memory use on your Linode: free -m You can use the following snippet to see a list of your running processes sorted by memory use: ps -eo pmem,pcpu,rss,vsize,args | sort -k 1 -r | less To see IO activity on your VPS, you may use the following command (you may need to install the sysstat package under Debian or Ubuntu first): iostat -d -x 2 5 This will give an extended device utilization report five times at two second intervals.
How to optimize subqueries and joins in MySQL at Xaprb I have written before about using joins instead of subqueries, especially for NOT IN queries, which can usually be rewritten as exclusion joins – sometimes with huge efficiency gains. In this article I’ll look more closely at the performance characteristics of a few queries I’ve optimized in MySQL 5.0.3. I’ll also show you some tricks you can use to get MySQL to optimize queries better when you know it’s being inefficient. Updates in a join I wrote recently about the theoretical problems caused by UPDATE statements with FROM clauses (Many-to-one problems in SQL). The application for this query is to update a table with aggregated clicks per day from a table of click-tracking data for online advertising. Since the tables are InnoDB, the clustered index is the primary key. For this article, I populated my tables with some pseudo-random data. Given a numbers table with at least 1,000 rows, here are scripts to populate the tables. Now that the tables are set up, I’ll move on to the queries.
Coder's Revolution: MySQL performance: INNER JOIN vs. sub-select I ran into an interesting behavior with MySQL this week. I was helping someone speed up a slow page and a sizable increase in performance was achieved by simply re-arranging the SQL statement. The page was calling a SQL statement inside of a loop-- probably around 150 times on a page load. My initial idea (and still the best long-term one I think) was to gather all the information from the database in a single cfquery and not hit the database over and over. That approach would have required quite a lot more refactoring of code, so first we tried to squeeze some better performance out of the SQL already being called.This site used MySQL which I am not as familiar with compared to MSSQL, but I started by looking at an EXPLAIN statement. In MySQL the placing the keyword EXPLAIN before your select will cause the engine to output a result set which describes how the select was performed. [code]EXPLAIN SELECT * FROM my_table WHERE column = 'foo'[/code]