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  • radius traffic accounting - what attributes do I use for traffic (and how)

    - by Mark Regensberg
    we are building a web front end for a internet access token management system that uses radius (freeradius) queried from a captive portal. Reason for building this part is the integration into the accounting and billing platform that operates behind the scenes (all other parts are currently available open source software) The structure is fairly standard, and setting up the basic bits were easy enough (authentication, traffic updates from the captive portal, account expiry date/times) - but I seem to have run out of ability when it comes to limiting an account by traffic consumed. So we can: set up usernames / passwords set expiry dates/times for a given user see the traffic for that user being accurately updated in RADACCT But we can't figure out the correct way/attribute to expire a user when they have consumed X octets of traffic. What attributes are used, or - maybe more accurately - what would be the correct way to use these attributes to limit an account to a certain volume of traffic? Any links to documentation appreciated - freeradius documentation doesn't seem to address the issue directly, or I'm looking in the wrong place... --mark

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  • Citrix Secure Gateway not redirecting to login URL

    - by Dave
    We have an older setup for XenApp - users log in through Citrix Secure Gateway running on a windows box. (We hope to start using a NetScaler soon.) Earlier today, connections to https://citrix.company.com/ starting throwing up a 503 error page, instead of redirecting to https://citrix.company.com/Citrix/XenApp/ If you go directly to the /Citrix/Xenapp/ URL, the user is properly directed to the login page, and can launch apps. We've restarted the service, and rebooted the server. We haven't yet tried uninstalling and reinstalling the software. Before we do this, I'm looking for ideas as to how we can get the redirect working again without a fairly major outage window. To make things more interesting, many of our users have Citrix Receiver installed, also pointed at https://citrix.company.com/. Receiver makes itself the default launcher for ICA files, and gives a connection error when it tries to load apps - probably because of the same non-functional rediect?

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  • Blank New Tab Quick-Fix for Google Chrome

    - by Asian Angel
    If you have other browsers that you use set to “about:blank” for new tabs then you probably feel rather frustrated with Google Chrome’s default New Tab Page. The Blank New Tab extension is the perfect solution to that problem. Before Unless you have a “speed dial/special page” extension installed you are stuck with the default new tab page in Chrome every single time you open a new tab. What if you do not like the default new tab page or “speed dial/special page” setups? After If you are someone who prefers to have a blank page as a new tab then you will love this extension. Once you have it installed you can click to your heart’s content on the “New Tab Button” and see nothing but blank goodness. Sometimes less is more… Note: There are no options to bother with. Conclusion If you prefer a blank page when opening a new tab then the Blank New Tab extension is just what you have been waiting for. Links Download the Blank New Tab extension (Google Chrome Extensions) Similar Articles Productive Geek Tips Subscribe to RSS Feeds in Chrome with a Single ClickAccess Wolfram Alpha Search in Google ChromeFind Similar Websites in Google ChromeHow to Make Google Chrome Your Default BrowserView Maps and Get Directions in Google Chrome TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Need Help with Your Home Network? Awesome Lyrics Finder for Winamp & Windows Media Player Download Videos from Hulu Pixels invade Manhattan Convert PDF files to ePub to read on your iPad Hide Your Confidential Files Inside Images

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  • postfix 5.7.1 Relay access denied when sending mail with cron

    - by zensys
    Reluctant to ask because there is so much here about 'postfix relay access denied' but I cannot find my case: I use php (Zend Framework) to send emails outside my network using the Google mail server because I could not send mail outside my server (user: web). However when I sent out an email via cron (user: root, I believe), still using ZF, using the same mail config/credentials, I get the message: '5.7.1 Relay access denied' I guess I need to know one of two things: 1. How can I use the google smtp server from cron 2. What do I need to change in my config to send mail using my own server instead of google Though the answer to 2. is the more structural solution I assume, I am quite happy with an answer to 1. as well because I think Google is better at server maintaince (security/spam) than I am. Below my ZF application.ini mail section, main.cf and master.cf: application.ini: resources.mail.transport.type = smtp resources.mail.transport.auth = login resources.mail.transport.host = "smtp.gmail.com" resources.mail.transport.ssl = tls resources.mail.transport.port = 587 resources.mail.transport.username = [email protected] resources.mail.transport.password = xxxxxxx resources.mail.defaultFrom.email = [email protected] resources.mail.defaultFrom.name = "my company" main.cf: # Debian specific: Specifying a file name will cause the first # line of that file to be used as the name. The Debian default # is /etc/mailname. #myorigin = /etc/mailname smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) biff = no # appending .domain is the MUA's job. append_dot_mydomain = no # Uncomment the next line to generate "delayed mail" warnings #delay_warning_time = 4h readme_directory = /usr/share/doc/postfix # TLS parameters smtpd_tls_cert_file = /etc/postfix/smtpd.cert smtpd_tls_key_file = /etc/postfix/smtpd.key smtpd_use_tls = yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for # information on enabling SSL in the smtp client. myhostname = mail.second-start.nl mydomain = second-start.nl alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases myorigin = /etc/mailname mydestination = relayhost = mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 mailbox_command = procmail -a "$EXTENSION" mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all html_directory = /usr/share/doc/postfix/html message_size_limit = 30720000 virtual_alias_domains = virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, mysql:/etc/postfix/mysql-virtual_email2email.cf virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf virtual_mailbox_base = /home/vmail virtual_uid_maps = static:5000 virtual_gid_maps = static:5000 smtpd_sasl_auth_enable = yes broken_sasl_auth_clients = yes smtpd_sasl_authenticated_header = yes # see under Spam smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $virtual_mailbox_limit_maps virtual_transport = dovecot dovecot_destination_recipient_limit = 1 # Spam disable_vrfy_command = yes smtpd_delay_reject = yes smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks, check_helo_access hash:/etc/postfix/helo_access, reject_non_fqdn_hostname, reject_invalid_hostname, permit smtpd_recipient_restrictions = permit_sasl_authenticated, reject_unauth_destination, reject_invalid_hostname, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unknown_sender_domain, reject_unknown_recipient_domain, permit_mynetworks, reject_non_fqdn_hostname, reject_rbl_client sbl.spamhaus.org, reject_rbl_client zen.spamhaus.org, reject_rbl_client cbl.abuseat.org, reject_rbl_client bl.spamcop.net, permit smtpd_error_sleep_time = 1s smtpd_soft_error_limit = 10 smtpd_hard_error_limit = 20 master.cf: # ========================================================================== # service type private unpriv chroot wakeup maxproc command + args # (yes) (yes) (yes) (never) (100) # ========================================================================== smtp inet n - - - - smtpd #smtp inet n - - - 1 postscreen #smtpd pass - - - - - smtpd #dnsblog unix - - - - 0 dnsblog #tlsproxy unix - - - - 0 tlsproxy #submission inet n - - - - smtpd # -o smtpd_tls_security_level=encrypt # -o smtpd_sasl_auth_enable=yes # -o smtpd_client_restrictions=permit_sasl_authenticated,reject # -o milter_macro_daemon_name=ORIGINATING #smtps inet n - - - - smtpd # -o smtpd_tls_wrappermode=yes # -o smtpd_sasl_auth_enable=yes # -o smtpd_client_restrictions=permit_sasl_authenticated,reject # -o milter_macro_daemon_name=ORIGINATING #628 inet n - - - - qmqpd pickup fifo n - - 60 1 pickup cleanup unix n - - - 0 cleanup qmgr fifo n - n 300 1 qmgr #qmgr fifo n - - 300 1 oqmgr tlsmgr unix - - - 1000? 1 tlsmgr rewrite unix - - - - - trivial-rewrite bounce unix - - - - 0 bounce defer unix - - - - 0 bounce trace unix - - - - 0 bounce verify unix - - - - 1 verify flush unix n - - 1000? 0 flush proxymap unix - - n - - proxymap proxywrite unix - - n - 1 proxymap smtp unix - - - - - smtp # When relaying mail as backup MX, disable fallback_relay to avoid MX loops relay unix - - - - - smtp -o smtp_fallback_relay= # -o smtp_helo_timeout=5 -o smtp_connect_timeout=5 showq unix n - - - - showq error unix - - - - - error retry unix - - - - - error discard unix - - - - - discard local unix - n n - - local virtual unix - n n - - virtual lmtp unix - - - - - lmtp anvil unix - - - - 1 anvil scache unix - - - - 1 scache # # ==================================================================== # Interfaces to non-Postfix software. Be sure to examine the manual # pages of the non-Postfix software to find out what options it wants. # # Many of the following services use the Postfix pipe(8) delivery # agent. See the pipe(8) man page for information about ${recipient} # and other message envelope options. # ==================================================================== # # maildrop. See the Postfix MAILDROP_README file for details. # Also specify in main.cf: maildrop_destination_recipient_limit=1 # maildrop unix - n n - - pipe flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient} # # ==================================================================== # # Recent Cyrus versions can use the existing "lmtp" master.cf entry. # # Specify in cyrus.conf: # lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4 # # Specify in main.cf one or more of the following: # mailbox_transport = lmtp:inet:localhost # virtual_transport = lmtp:inet:localhost # # ==================================================================== # # Cyrus 2.1.5 (Amos Gouaux) # Also specify in main.cf: cyrus_destination_recipient_limit=1 # #cyrus unix - n n - - pipe # user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user} # # ==================================================================== # Old example of delivery via Cyrus. # #old-cyrus unix - n n - - pipe # flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user} # # ==================================================================== # # See the Postfix UUCP_README file for configuration details. # uucp unix - n n - - pipe flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient) # # Other external delivery methods. # ifmail unix - n n - - pipe flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient) bsmtp unix - n n - - pipe flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient scalemail-backend unix - n n - 2 pipe flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension} mailman unix - n n - - pipe flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop} ${user} dovecot unix - n n - - pipe flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -d ${recipient}

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  • Automatic desktop/work environment setup

    - by Alex
    I have this strange thing I am trying to do, so before I jump into it I was curious if someone knows about existing solution or maybe have an advice as far as implementation. I run a small software company and as it happens I often do very different type of work. When I do coding for Java project I need Eclipse running and maybe VM with something like ActiveMQ server or whatever, plus terminals to tail -F log files specific to the application, etc. When I do something like weekly progress review with my team I need a few browser windows open and a gedit to take notes and so on. Depending on the type of work I am doing I generally have all of the related apps open in multiple different Workspaces. So in the example above Eclipse would be open in Workspace 1, terminals would be sharing Workspace 2 and so on. What I am trying to do is to automate opening of all these applications, positinoning them on the screen and assigning them to proper Workspaces. My current idea consists of having a Shell script that launches specific apps depending on what type of work I am about to start doing. Is there anything to aid this type of automation? Or is my only option is just a shell scripting at this point? My current system is Ubuntu 10.04

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  • DBan not working because disk has bad sectors? [migrated]

    - by canadiancreed
    Attempting to wipe the drive of a laptop that I have before it's sold, and normally use DBAN to do so. However this time it starts and then finishes instantly with the following message. "DBAN finished with non-fatal errors This is usually cause by disks with bad sectors" Have tried multiple flags such as noverify to force it to skip this check (it doesn't show bad sectors in the OS scan in windows). but the error always comes back. This is the only time that I've seen this message, as every other of the few drives I've used this software on usually take 3-5 hours to do their job.

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  • Free MP3 merge for Mac OS X

    - by Lilly
    Hi, I need to merge several MP3 tracks into one, I use Mac OS X 10.5. I want to convert all my Harry Potter CDs to my iPod, but not every minute a new track (as it is on the CDs) but chapterwise. Where can I get a free software? Help, please! (I've already tried: Jfuse, but after I had merged a few chapters it said I had to buy it; emicsoft VOB Converter for Mac; File Stitcher; but since they all were shareware, for free they would only let me merge 2 files at once (that would take me days) or half of each file which is useless of course; iTunes advanced settings ("join CD tracks") when importing the CDs, but it would let me only join the complete CD, not chapters...) (Sorry for my English, hope you could understand what I wanted to say)

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  • pfSense + DDoS Protection

    - by Jeremy
    I run a gaming community on a colo with a 100Mbps port. I want to buy a very cheap 35 dollar server with the same 100Mbps port, and run pfSense to use as a hardware firewall. I'm dealing with a bunch of 14 year old kids that have access to botnets, so it can become a bit necessary to get something like this. My overall question, is using pfSense on a cheap identical datacenter/port speed server worth it to actually block DDoS attacks? A bit more into detail since I assume you will ask this, the attacks we receive are normally around 1Gbps. We currently run CentOS using CSF Firewall, and even when using a software firewall, we block 500Mbps UDP floods, or just generic attacks pretty easily. Thanks, - Necro

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  • Can you upgrade OEM Office with an OEM Upgrade

    - by LuckyLindy
    We have a bunch of computers at work that have OEM Office 2000. We have all the material, CDs, etc., and amazingly the computers still work well (they were top of the line when purchased in 2002). However, we'd like to upgrade to Office 2003, our corporate standard. We've found OEM Office 2003 upgrade software online for ~$60 apiece, which would save us thousands over installing retail upgrades or volume licenses. But can we do this? I haven't been able to get a clear answer from Microsoft or anyone else if OEM Upgrades can be applied by non-System Builders to OEM Office.

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  • How does a PDF prevent itself from being printed?

    - by Steven
    I have a PDF for my camera's manual, and Adobe Reader won't let me print it (the print option is grayed out). SumatraPDF also does the same thing (it even says print denied). How does the PDF prevent itself from being printed? It seems that if the program can display it on the screen, then it can also print it. Maybe Adobe Reader respects the PDF not printing, but surely an open source PDF reader wouldn't be so restrictive. So is there something more to this than merely the PDF reader software respecting the PDF's request to not be able to be printed?

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  • Oracle VM VirtualBox 4.0 Now Available

    - by Paulo Folgado
    Delivering on Oracle's commitment to open source, Oracle VM VirtualBox 4.0 is now available, further enhancing the popular, open source, cross-platform virtualization software.   "Oracle VM VirtualBox 4.0 is the third major product release in just over a year, and adds to the many new product releases across the Oracle Virtualization product line, illustrating the investment and importance that Oracle places on providing a comprehensive desktop to datacenter virtualization solution," says Wim Coekaerts, senior vice president, Linux and Virtualization Engineering, Oracle. "With an improved user interface and added virtual hardware support, customers will find Oracle VM VirtualBox 4.0 provides a richer user experience." Part of Oracle's comprehensive portfolio of virtualization solutions, Oracle VM VirtualBox enables desktop or laptop computers to run multiple guest operating systems simultaneously, allowing users to get the most flexibility and utilization out of their PCs, and supports a variety of host operating systems, including Windows, Mac OS X, most popular flavors of Linux (including Oracle Linux), and Oracle Solaris. Oracle VM VirtualBox 4.0 delivers increased capacity and throughput to handle greater workloads, enhanced virtual appliance capabilities, and significant usability improvements. Support for the latest in virtual hardware, including chipsets supporting PCI Express, further extends the value delivered to customers, partners, and developers. Highlights of Oracle VM VirtualBox 4.0 include New Open Architecture - Oracle and community developers can now create extensions that customize Oracle VM VirtualBox and add features not previously available.Enhanced Usability - A new scalable display mode enables users to view more virtual displays on their existing monitors. Improvements to VM management, including visual VM previews, an optional attributes display, and easy launch shortcut creation enables administrators and power users to customize the interface to make it as simple or as comprehensive as required.Increased Capacity and Throughput - A new asynchronous I/O model for networked (iSCSI) and local storage delivers significant storage related performance improvements, while new optimizations allow larger datacenter-class workloads, such as Oracle's middeware, to be run on 32-bit Windows hosts for testing and demo purposes. Powerful Virtual Appliance Sharing Capabilities - Enhanced support for standards-compliant OVF appliances and added support for OVA format descriptors. All information about a VM may be stored in a single folder to facilitate easier direct sharing among VMs. Support for Latest Virtual Hardware - A new, modern virtual chipset supporting PCI Express and other hardware enhancements including high-definition audio devices helps ensure support for the most demanding virtual workloads.

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  • Upgrading openSUSE 11.1 with Plesk Panel 9.3 to PHP 5.3

    - by Jonathan
    I'm running a VPS with openSUSE 11.1 (i586). On the VPS is Parallels Plesk Panel 9.3.0 installed. The current PHP-version is PHP 5.2.11. I want to upgrade PHP to PHP 5.3, but I can't find good instructions on how to do this. If I check for updates in Zypper, it says this is the latest release. In the Plesk Updates isn't an update either, both via the webbased interface and the command line interface. On Software.openSUSE.org I can find packages for PHP 5.3.1 in both the server:php/server_apache_openSUSE_11.1-repo and the server:php/openSUSE_11.1-repo (can't post the link because I'm a newbie here). But if I add one of those to Zypper, I still don't see an update. Is there here somebody who knows how to do this? And is it completely safe to update that way? I don't want to end up with a broken VPS... Thanks! Jonathan

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  • How much system and business analysis should a programmer be reasonably expected to do?

    - by Rahul
    In most places I have worked for, there were no formal System or Business Analysts and the programmers were expected to perform both the roles. One had to understand all the subsystems and their interdependencies inside out. Further, one was also supposed to have a thorough knowledge of the business logic of the applications and interact directly with the users to gather requirements, answer their queries etc. In my current job, for ex, I spend about 70% time doing system analysis and only 30% time programming. I consider myself a good programmer but struggle with developing a good understanding of the business rules of a complex application. Often, this creates a handicap because while I can write efficient algorithms and thread-safe code, I lose out to guys who may be average programmers but have a much better understanding of the business processes. So I want to know - How much business and systems knowledge should a programmer have ? - How does one go about getting this knowledge in an immensely complex software system (e.g. trading applications) with several interdependent business processes but poorly documented business rules.

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  • the brightness controls buttons are not working on my HP Dm3t notebook with windows xp, any suggetio

    - by Karim
    i have an HP dm3t notebook which normally comes with windows 7. after some time i figured out how to install Windows XP on it. but now i am facing a problem that the brightess controls dont work so i am unable to change the brightess. the strange thing is that all the other buttons (sound volume, mute, sleep , etc... ) works but not the 2 brightess controls. i already downloaded the "HP Quick Launch Buttons" so i am asking about suggesitions how can i enable these two buttons in windows XP or even if i can change the brightess using some kind of software. thanks

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  • Adobe Flash not working anymore with Browsers

    - by Marcus
    Hi guys, I have a really annoying problem: essentially, Adobe Flash is not working anymore. For instance, I cant watch any clip on youtube and I always get a black screen saying: Movie not loaded ... I have the newest Flash version (10.0.45.2), and the problem is the same with IE, Firefox or Chrome. I am using WIN XP and I turned of Antivirus software as well as Firewall, still I cant watch any flash stuff. Anyone an idea what could have happened in the last week? Never had a problem before that! Thanks!

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  • Unable to connect to wireless internet(wifi) through KDE plasma desktop

    - by Mohammed Arafat Kamaal
    I installed the KDE plasma desktop through Ubuntu software center. I am on Ubuntu Lucid Lynx. After the install, Im unable to connect to my wifi connection in the KDE session. But I can connect to my wifi perfectly through GNOME session. I've tried a lot without much success. Also KDE doesn't store my password correctly and keeps prompting for authorization again and again. Some of the things that I noticed. Network is detected, Network name and strength is also displayed. Other characteristics also appear properly. When the credentials are supplied, it accepts them and continually displays the message "Setting network address". However this process never succeeds. At this stage the password is repeatedly asked many times but the connection is never established. Some of the other things that I did, I have also tried other things like restarting my modem and the computer. That didn't work. I tried to restart nm-applet and KNetworkManager. That didn't work either. ifconfig display all my interfaces and Mac addresses correctly. Since its working fine GNOME the drivers are fine. This is sure a KDE specific issue. Other threads related to this on the interwebs don't offer much information either. Please share a solution for this.

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  • Organizations &amp; Architecture UNISA Studies &ndash; Chap 7

    - by MarkPearl
    Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External Devices An external device attaches to the computer by a link to an I/O module. The link is used to exchange control, status, and data between the I/O module and the external device. External devices can be classified into 3 categories… Human readable – e.g. video display Machine readable – e.g. magnetic disk Communications – e.g. wifi card I/O Modules An I/O module has two major functions… Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Module Functions The major functions or requirements for an I/O module fall into the following categories… Control and timing Processor communication Device communication Data buffering Error detection I/O function includes a control and timing requirement, to coordinate the flow of traffic between internal resources and external devices. Processor communication involves the following… Command decoding Data Status reporting Address recognition The I/O device must be able to perform device communication. This communication involves commands, status information, and data. An essential task of an I/O module is data buffering due to the relative slow speeds of most external devices. An I/O module is often responsible for error detection and for subsequently reporting errors to the processor. I/O Module Structure An I/O module functions to allow the processor to view a wide range of devices in a simple minded way. The I/O module may hide the details of timing, formats, and the electro mechanics of an external device so that the processor can function in terms of simple reads and write commands. An I/O channel/processor is an I/O module that takes on most of the detailed processing burden, presenting a high-level interface to the processor. There are 3 techniques are possible for I/O operations Programmed I/O Interrupt[t I/O DMA Access Programmed I/O When a processor is executing a program and encounters an instruction relating to I/O it executes that instruction by issuing a command to the appropriate I/O module. With programmed I/O, the I/O module will perform the requested action and then set the appropriate bits in the I/O status register. The I/O module takes no further actions to alert the processor. I/O Commands To execute an I/O related instruction, the processor issues an address, specifying the particular I/O module and external device, and an I/O command. There are four types of I/O commands that an I/O module may receive when it is addressed by a processor… Control – used to activate a peripheral and tell it what to do Test – Used to test various status conditions associated with an I/O module and its peripherals Read – Causes the I/O module to obtain an item of data from the peripheral and place it in an internal buffer Write – Causes the I/O module to take an item of data form the data bus and subsequently transmit that data item to the peripheral The main disadvantage of this technique is it is a time consuming process that keeps the processor busy needlessly I/O Instructions With programmed I/O there is a close correspondence between the I/O related instructions that the processor fetches from memory and the I/O commands that the processor issues to an I/O module to execute the instructions. Typically there will be many I/O devices connected through I/O modules to the system – each device is given a unique identifier or address – when the processor issues an I/O command, the command contains the address of the address of the desired device, thus each I/O module must interpret the address lines to determine if the command is for itself. When the processor, main memory and I/O share a common bus, two modes of addressing are possible… Memory mapped I/O Isolated I/O (for a detailed explanation read page 245 of book) The advantage of memory mapped I/O over isolated I/O is that it has a large repertoire of instructions that can be used, allowing more efficient programming. The disadvantage of memory mapped I/O over isolated I/O is that valuable memory address space is sued up. Interrupts driven I/O Interrupt driven I/O works as follows… The processor issues an I/O command to a module and then goes on to do some other useful work The I/O module will then interrupts the processor to request service when is is ready to exchange data with the processor The processor then executes the data transfer and then resumes its former processing Interrupt Processing The occurrence of an interrupt triggers a number of events, both in the processor hardware and in software. When an I/O device completes an I/O operations the following sequence of hardware events occurs… The device issues an interrupt signal to the processor The processor finishes execution of the current instruction before responding to the interrupt The processor tests for an interrupt – determines that there is one – and sends an acknowledgement signal to the device that issues the interrupt. The acknowledgement allows the device to remove its interrupt signal The processor now needs to prepare to transfer control to the interrupt routine. To begin, it needs to save information needed to resume the current program at the point of interrupt. The minimum information required is the status of the processor and the location of the next instruction to be executed. The processor now loads the program counter with the entry location of the interrupt-handling program that will respond to this interrupt. It also saves the values of the process registers because the Interrupt operation may modify these The interrupt handler processes the interrupt – this includes examination of status information relating to the I/O operation or other event that caused an interrupt When interrupt processing is complete, the saved register values are retrieved from the stack and restored to the registers Finally, the PSW and program counter values from the stack are restored. Design Issues Two design issues arise in implementing interrupt I/O Because there will be multiple I/O modules, how does the processor determine which device issued the interrupt? If multiple interrupts have occurred, how does the processor decide which one to process? Addressing device recognition, 4 general categories of techniques are in common use… Multiple interrupt lines Software poll Daisy chain Bus arbitration For a detailed explanation of these approaches read page 250 of the textbook. Interrupt driven I/O while more efficient than simple programmed I/O still requires the active intervention of the processor to transfer data between memory and an I/O module, and any data transfer must traverse a path through the processor. Thus is suffers from two inherent drawbacks… The I/O transfer rate is limited by the speed with which the processor can test and service a device The processor is tied up in managing an I/O transfer; a number of instructions must be executed for each I/O transfer Direct Memory Access When large volumes of data are to be moved, an efficient technique is direct memory access (DMA) DMA Function DMA involves an additional module on the system bus. The DMA module is capable of mimicking the processor and taking over control of the system from the processor. It needs to do this to transfer data to and from memory over the system bus. DMA must the bus only when the processor does not need it, or it must force the processor to suspend operation temporarily (most common – referred to as cycle stealing). When the processor wishes to read or write a block of data, it issues a command to the DMA module by sending to the DMA module the following information… Whether a read or write is requested using the read or write control line between the processor and the DMA module The address of the I/O device involved, communicated on the data lines The starting location in memory to read from or write to, communicated on the data lines and stored by the DMA module in its address register The number of words to be read or written, communicated via the data lines and stored in the data count register The processor then continues with other work, it delegates the I/O operation to the DMA module which transfers the entire block of data, one word at a time, directly to or from memory without going through the processor. When the transfer is complete, the DMA module sends an interrupt signal to the processor, this the processor is involved only at the beginning and end of the transfer. I/O Channels and Processors Characteristics of I/O Channels As one proceeds along the evolutionary path, more and more of the I/O function is performed without CPU involvement. The I/O channel represents an extension of the DMA concept. An I/O channel ahs the ability to execute I/O instructions, which gives it complete control over I/O operations. In a computer system with such devices, the CPU does not execute I/O instructions – such instructions are stored in main memory to be executed by a special purpose processor in the I/O channel itself. Two types of I/O channels are common A selector channel controls multiple high-speed devices. A multiplexor channel can handle I/O with multiple characters as fast as possible to multiple devices. The external interface: FireWire and InfiniBand Types of Interfaces One major characteristic of the interface is whether it is serial or parallel parallel interface – there are multiple lines connecting the I/O module and the peripheral, and multiple bits are transferred simultaneously serial interface – there is only one line used to transmit data, and bits must be transmitted one at a time With new generation serial interfaces, parallel interfaces are becoming less common. In either case, the I/O module must engage in a dialogue with the peripheral. In general terms the dialog may look as follows… The I/O module sends a control signal requesting permission to send data The peripheral acknowledges the request The I/O module transfers data The peripheral acknowledges receipt of data For a detailed explanation of FireWire and InfiniBand technology read page 264 – 270 of the textbook

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  • Talking JavaOne with Rock Star Raghavan Srinivas

    - by Janice J. Heiss
    Raghavan Srinivas, affectionately known as “Rags,” is a two-time JavaOne Rock Star (from 2005 and 2011) who, as a Developer Advocate at Couchbase, gets his hands dirty with emerging technology directions and trends. His general focus is on distributed systems, with a specialization in cloud computing. He worked on Hadoop and HBase during its early stages, has spoken at conferences world-wide on a variety of technical topics, conducted and organized Hands-on Labs and taught graduate classes.He has 20 years of hands-on software development and over 10 years of architecture and technology evangelism experience and has worked for Digital Equipment Corporation, Sun Microsystems, Intuit and Accenture. He has evangelized and influenced the architecture of numerous technologies including the early releases of JavaFX, Java, Java EE, Java and XML, Java ME, AJAX and Web 2.0, and Java Security.Rags will be giving these sessions at JavaOne 2012: CON3570 -- Autosharding Enterprise to Social Gaming Applications with NoSQL and Couchbase CON3257 -- Script Bowl 2012: The Battle of the JVM-Based Languages (with Guillaume Laforge, Aaron Bedra, Dick Wall, and Dr Nic Williams) Rags emphasized the importance of the Cloud: “The Cloud and the Big Data are popular technologies not merely because they are trendy, but, largely due to the fact that it's possible to do massive data mining and use that information for business advantage,” he explained. I asked him what we should know about Hadoop. “Hadoop,” he remarked, “is mainly about using commodity hardware and achieving unprecedented scalability. At the heart of all this is the Java Virtual Machine which is running on each of these nodes. The vision of taking the processing to where the data resides is made possible by Java and Hadoop.” And the most exciting thing happening in the world of Java today? “I read recently that Java projects on github.com are just off the charts when compared to other projects. It's exciting to realize the robust growth of Java and the degree of collaboration amongst Java programmers.” He encourages Java developers to take advantage of Java 7 for Mac OS X which is now available for download. At the same time, he also encourages us to read the caveats. Originally published on blogs.oracle.com/javaone.

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  • Talking JavaOne with Rock Star Raghavan Srinivas

    - by Janice J. Heiss
    Raghavan Srinivas, affectionately known as “Rags,” is a two-time JavaOne Rock Star (from 2005 and 2011) who, as a Developer Advocate at Couchbase, gets his hands dirty with emerging technology directions and trends. His general focus is on distributed systems, with a specialization in cloud computing. He worked on Hadoop and HBase during its early stages, has spoken at conferences world-wide on a variety of technical topics, conducted and organized Hands-on Labs and taught graduate classes.He has 20 years of hands-on software development and over 10 years of architecture and technology evangelism experience and has worked for Digital Equipment Corporation, Sun Microsystems, Intuit and Accenture. He has evangelized and influenced the architecture of numerous technologies including the early releases of JavaFX, Java, Java EE, Java and XML, Java ME, AJAX and Web 2.0, and Java Security.Rags will be giving these sessions at JavaOne 2012: CON3570 -- Autosharding Enterprise to Social Gaming Applications with NoSQL and Couchbase CON3257 -- Script Bowl 2012: The Battle of the JVM-Based Languages (with Guillaume Laforge, Aaron Bedra, Dick Wall, and Dr Nic Williams) Rags emphasized the importance of the Cloud: “The Cloud and the Big Data are popular technologies not merely because they are trendy, but, largely due to the fact that it's possible to do massive data mining and use that information for business advantage,” he explained. I asked him what we should know about Hadoop. “Hadoop,” he remarked, “is mainly about using commodity hardware and achieving unprecedented scalability. At the heart of all this is the Java Virtual Machine which is running on each of these nodes. The vision of taking the processing to where the data resides is made possible by Java and Hadoop.” And the most exciting thing happening in the world of Java today? “I read recently that Java projects on github.com are just off the charts when compared to other projects. It's exciting to realize the robust growth of Java and the degree of collaboration amongst Java programmers.” He encourages Java developers to take advantage of Java 7 for Mac OS X which is now available for download. At the same time, he also encourages us to read the caveats.

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  • List SQL Server Instances using the Registry

    - by BuckWoody
    I read this interesting article on using PowerShell and the registry, and thought I would modify his information a bit to list the SQL Server Instances on a box. The interesting thing about listing instances this was is that you can touch remote machines, find the instances when they are off and so on. Anyway, here’s the scriptlet I used to find the Instances on my system: $MachineName = '.' $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $MachineName) $regKey= $reg.OpenSubKey("SOFTWARE\\Microsoft\\Microsoft SQL Server\\Instance Names\\SQL" ) $regkey.GetValueNames() You can read more of his article to find out the reason for the remote registry call and so forth – there are also security implications here for being able to read the registry. Script Disclaimer, for people who need to be told this sort of thing: Never trust any script, including those that you find here, until you understand exactly what it does and how it will act on your systems. Always check the script on a test system or Virtual Machine, not a production system. Yes, there are always multiple ways to do things, and this script may not work in every situation, for everything. It’s just a script, people. All scripts on this site are performed by a professional stunt driver on a closed course. Your mileage may vary. Void where prohibited. Offer good for a limited time only. Keep out of reach of small children. Do not operate heavy machinery while using this script. If you experience blurry vision, indigestion or diarrhea during the operation of this script, see a physician immediately. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Why does 1080p through a VGA cable fit my HDTV but is oversized when through an HDMI cable?

    - by GraemeF
    I have put together a new PC with a XFX GeForce GTX 260 graphics card and have it connected to my HDTV. First, I used an old VGA cable with a DVI to VGA adapter and plugged it in to my HDTV's VGA port. Running at 1920x1080 it fit the screen perfectly. Now, to avoid running another cable across the room, I have connected it with a DVI to HDMI cable to my TV's HDMI port, and the desktop at 1920x1080 is cropped by the edge of the screen. I have "fixed" the cropping by using NVIDIA's "Adjust desktop size and position" tool, which created a screen resolution of 1814x1022 to fit the screen, but this is no longer the TV's native resolution and confuses some software (e.g. WoW). Why does VGA work as expected, but HDMI is scaled up? Can it be avoided?

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  • Smarter System Alerts

    - by mellowsoon
    We have a pretty simple system setup, where I get text messages when there is a system problem. It's nothing fancy. I send an email to my phone number within my logging class for alert levels. It works well enough, but it has one major flaw: A small hiccup in the system/site can turn into dozens of rapid fire text messages. Sometimes non-stop text messages until I log into the system and fix the problem. So I'm looking for pointers on software or services I can use that deal with alerts in a smarter way. Perhaps something that only sends me alerts X number of times within Y number of minutes. I'm not looking for a full monitoring suite. We already deal with that in house. I'm only looking to tackle this single problem.

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  • VMware Virtualisation - Convert 64bit Windows Server to 32bit VM?

    - by dannymcc
    I have just started playing around with Vmware sphere and have the hypervisor OS installed on a spare HP ProLiant DL360 G4. I have created a test virtual machine running Ubuntu which has worked well. As a test project I wanted to convert a powered on server running Windows Server 2008 64bit into a virtual machine. As soon as I ran the Vmware Go software to start the conversion it became apparent that I cannot run 64bit guest OS's on that particular server. So, is there a way of migrating 64bit to 32bit during the conversion?

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  • Coding in large chunks ... Code verification skills

    - by Andrew
    As a follow up to my prev question: What is the best aproach for coding in a slow compilation environment To recap: I am stuck with a large software system with which a TDD ideology of "test often" does not work. And to make it even worse the features like pre-compiled headers/multi-threaded compilation/incremental linking, etc is not available to me - hence I think that the best way out would be to add the extensive logging into the system and to start "coding in large chunks", which I understand as code for a two-three hours first (as opposed to 15-20 mins in TDD) - thoroughly eyeball the code for a 15 minutes and only after all that do the compilation and run the tests. As I have been doing TDD for a quite a while, my code eyeballing / code verification skills got rusty (you don't really need this that much if you can quickly verify what you've done in 5 seconds by running a test or two) - so I am after a recommendations on how to learn these source code verification/error spotting skills again. I know I was able to do that easily some 5-10 years ago when I din't have much support from the compiler/unit testing tools I had until recently, thus there should be a way to get back to the basics.

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  • RAID1 Hard drives with Intel Controller

    - by Dave_H
    I have an older server with 2 35GB hard drives arranged as a RAID-1 drive. I have 3 open bays, I'd like to add 2 more hard drives to the open bays and have all 4 drives configured as a RAID-1 drive that Windows sees as 1 larger drive. Is this possible? If not, the new drives are 2x as big as the old drives, is it possible to replace 1 of the old drives and rebuild then replace the second drive and rebuild and somehow expand the array to use all of the available space? The server is using an Intel hardware raid controller, the software interface is Intel Storage Console v2.12.

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