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• PFSENSE and IPV6 , direct connect rules

  - by Bgnt44

  My question is about pfsense configuration for ipv6 In theory Ipv6 are fully routable even in a LAN For stating point i ve Using this tutorial : http://doc.pfsense.org/index.php/Using_IPv6_on_2.1_with_a_Tunnel_Broker So my Lan network has ipv4 connection and ipv6 I would like to be able to access my LAN machines by their IPV6 i'm confused with firewall rules which i need to set to be able to do that Even if i set all interfaces to pass all packets, i'm not able to directly access any machine by their IPV6 Did i miss something ? Edit : Ok i found that it work now, think it has always work but my isp seems to support ipv6 sometimes and sometimes not ... weird

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• SSL certificate for ISAPI redirected Web Site

  - by Daniel

  I have a Win 2003 server and I'm using Ionics Isapi Rewrite Filter to redirect requests made to a Web Site configured in IIS to another Apache2 Server in a server not exposed to the Internet. The Web Site has its host headers configured to catch requests for the specific site, and the redirection is being done with the ProxyPass directive. This is working OK. So far the scenario, my question is: I'd like to add a server certificate to the Apache server, but I don´t know if I need to add the certificate to both Apache and IIS sites. I think I still don´t get the theory behind this and would like to know from someone with expertise in the field the right way to implement this. Thank you in advance.

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• limit linux background flush (dirty pages)

  - by korkman

  Background flushing in linux happens when either too much written data is pending (adjustable via /proc/sys/vm/dirty_background_ratio) or a timeout for pending writes is reached (/proc/sys/vm/dirty_expire_centisecs). Unless another limit is being hit (/proc/sys/vm/dirty_ratio), more written data may be cached. Further writes will block. In theory, this should create a background process writing out dirty pages without disturbing other processes. In practice, it does disturb any process doing uncached reading or synchronous writing. Badly. This is because the background flush actually writes at 100% device speed and any other device requests at this time will be delayed (because all queues and write-caches on the road are filled). Is there any way to limit the amount of requests per second the flushing process performs, or otherwise effectively prioritize other device I/O?

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• How would I / could I obtain an reasonably comprehensive list of domain names?

  - by Simon

  I know that domain names are constantly changing, and I know there are a lot of them, but there is clearly a region of the domain name space which is stable. How would I go about getting a list, even a very big one? Such a thing must logically exist, even if it is in a distributed form, because the web's DNS servers resolve names to IP addresses. So in theory if I could poll all the DNS servers in the world at a moment in time I would have the complete list of mapped names. Is there a practical way of doing that? As an aside, does anyone have any good estimates of how many domain names exist at the moment?

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• Is mismatched firmware on drives in a raid-6 a bad thing?

  - by bwerks

  Hi all, I recently expanded a raid-1 to a raid-6 with six drives. I ordered all four of the new drives from the same place, and all of them were advertised to be the same drives as the original two--Seagate 15krpm 146gb. However, when I was looking at the drives in the perc6/i utility, one of them appeared to be an earlier firmware version; it had S515, compared to the other five drives with S527. Sure enough, after inspecting the drive itself, the label advertised the earlier firmware version. Running Dell's SAS firmware upgrade utility should have in theory moved them all up to S52A, but when I ran it it moved the S527 drives up to S52A, and left the S515 drive untouched. Is this something to be worried about? If it's something that should be corrected, is there a way to target a particular drive for upgrade since the firmware utility didn't seem to do it by itself?

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• Does Lapping a CPU / Heatsink actually drop the temp?

  - by Pure.Krome

  Hi folks, i've been watching some YouTube vids about Lapping a CPU. I've never heard of this modding technique before and, though extreame, I was wondering if it acutally works? Assuming you lap your cpu and/or heatsink correctly, will the temps drop? When I say drop, at least a 1 degree drop is success (for the debate of this topic). To keep this topic clean, please refrain from anyone commenting on the overkill of labour, just for a 1 degree (worst case) drop, etc. This is a discussion about the theory and concept, not personal opionion of wether to lap or not.

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• Is there a way to bridge two outgoing TCP connections in order to bypass firewalls and NAT?

  - by TK Kocheran

  We're all familiar with the problem of port-forwarding and NAT: if you want to expose something to accepting an incoming connection, you need to configure port-forwarding on the router or conjure up some other black magickery to "punch holes" in the firewall using UDP or something. I'm fairly new to the whole "hole-punching" concept so could someone explain how it works? Essentially, I'd like to understand how hole-punching would work and the theory behind it, as well as if two TCP connections could be bridged via a third party. Since there's no issue with outgoing TCP connections since it's handled with NAT, could a third party bridge the connections so that the two parties are still connected but without the bandwidth cost of traffic going through the third party?

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• Load balance between two virtual directories on a single machine running IIS6

  - by Emil Lerch

  I'm trying to simulate a production environment using a single VM. The production environment will have 3 servers behind a load balancer with sticky sessions. Production will be using IIS6. For development, I have no need to distribute load, but I want to make sure the team does not write code that relies on a single-server module. I have been hoping to set up two virtual directories and find some isapi filter to perform some rudimentary software load balancing, but I've been unable to locate anything suitable. isapi_rewrite comes close but there's no ability for a random rewrite. I don't even need sticky sessions since the application does not (in theory) rely on them. Is there something easy/free to do this, or am I stuck with multiple VMs and a NLB setup (which seems like total overkill)?

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• Apache vs Lighttpd: Weird behavior in reverse proxy mode.

  - by northox

  Context: I have an Apache server running in reverse proxy mode in front of a Tomcat java server. It handle HTTP and HTTPS and send those request back and forth to the Tomcat server on an internal HTTP port. Goal: I'm trying to replace the reverse proxy with Lighttpd. Problem: while asking for the same HTTPS url, while using Apache as the reverse proxy, the Tomcat server redirect (302) to an HTTPS page but with Lighttpd it redirect to the same page in HTTP (not HTTPS). Question: What does Lighttpd could do different in order to have a different result from the backend server? In theory, using Apache or Lighttpd server as a reverse proxy should not change anything... but it does. Any idea? I'll try to find something by sniffing the traffic on the backend tomcat server.

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• Overcrowded Windows XP Folders

  - by BlairHippo

  I know that, technically, an individual Windows XP directory can hold an immense number of files (over 4.29 billion, according to a quick Google search). However, is there a practical ceiling where too many files in one directory starts having an impact on reads to those files? If so, what factors would exacerbate or help the issue? I ask because my employer has several hundred XP machines in the field at client sites, and the performance on some of the older ones is getting "sludgy." The machines download and display client-defined images, and my supervisor and I suspect that our slacktastic approach to cache management could be to blame. (Some of the directories have tens of thousands of images in them.) I'm trying to gather evidence to support or contest the theory before spending time on a coding fix.

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• Logstash shipper & server on the samebox

  - by keftes

  I'm trying to setup a central logstash configuration. However I would like to be sending my logs through syslog-ng and not third party shippers. This means that my logstash server is accepting via syslog-ng all the logs from the agents. I then need to install a logstash process that will be reading from /var/log/syslog-clients/* and grabbing all the log files that are sent to the central log server. These logs will then be sent to redis on the same VM. In theory I need to also configure a second logstash process that will read from redis and start indexing the logs and send them to elasticsearch. My question: Do I have to use two different logstash processes (shipper & server) even if I am in the same box (I want one log server instance)? Is there any way to just have one logstash configuration and have the process read from syslog-ng --- write to redis and also read from redis --- output to elastic search ? Diagram of my setup: [client]-------syslog-ng--- [log server] ---syslog-ng <----logstash-shipper --- redis <----logstash-server ---- elastic-search <--- kibana

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• CRL checking problem windows 2003

  - by Tim Mahy

  Hi all, we have CRL that is valid for 24 hours and has a next update in 12 hours. The CRL is valid from 12:12 AM to 12:12 AM and from 12:12 PM to 12:12 PM. In the logs of the CRL hosting webserver we see that one of our servers not always fetches the CRL at night, in most cases the server that missed the CRL IIS servers 403.16 on 12:13 PM. Is our following theory good: when a windows server misses fetching the CRL on it's nextUpdate but the current CRL is still valid, the fetching is not retried? This leads to a situation that when the CRL expires there is no overlap and gives a little time of 403.16 situations in IIS since the CRL is not thrusted and so all certificates are marked als unsafe? greetings, Tim

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• Are there any free voice transcription software?

  - by netvope

  I have some 1-hour-long voice recordings containing useful information that I may need to look up in the future. Instead of transcribing them myself (which will take me many hours), I want to automate it using software. I don't need an accurate transcription; it's OK as long as I can get an idea of what was being talked about by skimming over the transcription. With this, I can quickly figure out which part of the audio contains the information I need, and is much more convenient than seeking randomly. In theory I could write a program to split the audio into 3 minutes chucks and pipe them into Google Voice's free voicemail transcription service... But I hope there are better solutions. Do you know any free voice transcription software? Note: Free trials are also acceptable

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• environment variable issue in shell

  - by George2

  I am using Red Hat Linux Enterprise 5. I know the theory that -- using export to set environment variable, the environment variable will apply to current and child environment, but without using export to set environment variable, the environment variable will only apply to the current environment. My confusion is, what is the exact definition of "child environment" and "current environment"? For example, $ var1=123 $ echo "Hello [$var1]" the value of var1 (which is 123) is printed in shell, but I think echo is a command invoked by current shell, and it (the echo command) should be a child environment of current shell and the value of var1 should not (because not using export var1=123) impact echo. Any comments? Thanks in advance!

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• Unset the system immutable bit in Mac OS X

  - by skylarking

  In theory I believe you can unlock and remove the system immutable bit with: chflags noschg /Path/To/File But how can you do this when you've set the bit as root? I have a file that is locked, and even running this command as root will not work as the operation is not permitted. I tried logging in as Single-User mode to no avail. I seem to remember that even though you are in as root you are in at level '1'. And to be able to remove the system-immutable flag you need to be logged in at level '0'. Does this have something to do with this issue?

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• How to recover data from software RAID 5 disk partition

  - by Ali n

  I have CentOS 5.8 on my computer, with 5x 1TB hard drives. I used software RAID. (RAID 1 as a boot partition md0, RAID 0 as a root partition md1 and RAID 5 as /home partition md3). Unfortunately one of these hard drives failed lately and I want to replace it with a new one. I want to know that is it possible to change this hard drive without data loss? The important partition is RAID 5 so in theory if one of hard drives failed I should be able to recover its data without any problem. But in practice how can I do that?

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• Using Gentoo's `ebegin`, `eend` etc under Ubuntu

  - by Marcus Downing

  We're quite fond of the style of the ebegin, eend, eerror, eindent etc commands used by Portage and other tools on Gentoo. The green-yellow-red bullets and standard layout make for very quick spotting of errors, on what would otherwise be very grey command line output. #!/bin/sh source /etc/init.d/functions.sh ebegin "Copying data" rsync .... eend $? Producing output similar to: * Copying data... [ OK ] As a result we're using these commands in some of our common shell scripts, which is a problem for the people using Ubuntu and other linuxes. (linuces? linuxen? linucae? other distros) On Gentoo these functions are provided by OpenRC, and imported with functions.sh file (whose exact position seems to vary slightly). But is there a simple way of getting these commands on Ubuntu? In theory we could replace them all with dull echos, but we'd rather not?

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• Which Wine DLLs should I *not* overwrite with the real thing?

  - by endolith

  I have a legit installation of Windows XP and dual boot with Ubuntu (currently Karmic). WineHQ says it's possible to use DLLs from a real installation of Windows in place of "DLLs that Wine does not currently implement very well". So I'd like to just create softlinks that point to all of the DLLs in my real Windows System32 folder, under the theory that this would help things function better and behave in a less buggy, more native way. But should I go as far as replacing the Wine DLLs with the real ones? If so, are there any DLLs that need to remain the way they are for compatibility with the Linux world? Which ones are safe to replace?

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• How do UEFI and virtual machines relate to each other?

  - by Iterator

  I am trying to get my head around UEFI (Unified Extensible Firmware Interface) and it's not entirely clear to me how this affects virtual machines. Thus, there are three parts to this question: Is UEFI an advance in hardware support for virtualization? All other things being equal, would a machine with UEFI be more likely to run a virtual machine more efficiently than one without, or does UEFI cause any performance hits that negate any speed improvements from a virtual machine? Would the difference in execution be visible to code running in a virtual machine? (In theory, it shouldn't, but in practice?)

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• How can I improve performance over SMB/CIFS for an application that has poor write speeds?

  - by Jeremy

  I have a third party application that reads several large files and generates a third large file. Its performance is quite good when the generated file is stored on "local storage", i.e. either a direct attached or iSCSI-based disk. The source files that are read can be stored remotely on our NAS and accessed via SMB with little effect on performance. However, if we attempt to write the target file to any kind of SMB/CIFS share (Samba or Windows Server) the performance drops almost ten-fold. This is unacceptably slow in our case. Writing files to network shares is not otherwise slow. I can copy large files to SMB shares and get great performance - near what I would expect is possible given the disks and network in question. I have a theory that this application's problem with SMB shares has something to do with a lack of write caching over the share and perhaps lots of network roundtrips. Is this possible and is there anything that can be done about it?

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• CPU Affinity on ARM processors

  - by dsljanus

  I am using some RaspberryPI boards for a data acquisition system. They are nice boards, with plenty of community support around them, but they are really slow. I am thinking of gradually replacing them with ODROID multicore boards, with the Samsung Exynos processors. I have some experience using taskset to set CPU affinity on my servers because I am always running Node.js applications that are by definition single threaded. Now, is it possible to do this on an ARM board? I do not see why it would not in theory, but I have doubts over how well it is going to work. Does anyone have experience with this kind of hack? Also, I would appreciate any comments about ARM CPUs and how they differ from x86.

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• Using "mv" or "ditto" to merge folders in OS X

  - by Sandro Dzneladze

  Used to the Windows way of doing I just found out OS X has no merge function – moving means replacing the folder. While this does make sense, I miss merging! I've two Wordpress directories, 1 contains default source and 2 contains worked version with plugins custom theme etc. I want to see difference between this two, so I'm putting it on SVN. Folder 1 is already up, now in theory I should simply merge contents of 2 with 1 by replacing everything with contents of 2 but leaving hidden SVN files untouched. Unfortunately OS X, when moving, replaces the folder so that my SVN client goes crazy and doesn't understand folder structure anymore. So, I believe my options are mv and ditto, but which one would you use in my situation and how? sudo mv wordpress /Documents/svn/wwwholiday/trunk/wordpress I want mv to overwrite everything it finds, but leave alone whatever is already inside folder 1 and has no duplicate in folder 2.

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• How to tell if linux disk IO is causing excessive (> 1 second) application stalls

  - by noahz

  I have a Java application performing a large volume (hundreds of MB) of continuous output (streaming plain text) to about a dozen files a ext3 SAN filesystem. Occasionally, this application pauses for several seconds at a time. I suspect that something related to ext3 vsfs (Veritas Filesystem) functionality (and/or how it interacts with the OS) is the culprit. What steps can I take to confirm or refute this theory? I am aware of iostat and /proc/diskstats as starting points. Revised title to de-emphasize journaling and emphasize "stalls" I have done some googling and found at least one article that seems to describe behavior like I am observing: Solving the ext3 latency problem Additional Information Red Hat Enterprise Linux Server release 5.3 (Tikanga) Kernel: 2.6.18-194.32.1.el5 Primary application disk is fiber-channel SAN: lspci | grep -i fibre 14:00.0 Fibre Channel: Emulex Corporation Saturn-X: LightPulse Fibre Channel Host Adapter (rev 03) Mount info: type vxfs (rw,tmplog,largefiles,mincache=tmpcache,ioerror=mwdisable) 0 0 cat /sys/block/VxVM123456/queue/scheduler noop anticipatory [deadline] cfq

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• Tools for analyzing performance of SQL Server/Express?

  - by Adam Crossland

  The application that I have customized and continue to support for my client is seeing dramatic performance problems in the field. Simple queries on rather small datasets take over a minute when I would expect them to complete with sub-second times. My current theory is that SQL Server Express 2005 is too limited for the rather non-trivial demands being made of it, but I am not sure how to get about gathering data that I can use to either prove my point or allow me to move on to finding another cause. Can anyone point me toward some tools that would allow me to analyze the load on this database? Information such as simultaneous connections, execution times of individual queries, memory usage, heck just any profiling data at all would be a help. Many thanks.

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• How to put 1000 lightweight server applications in the cloud

  - by Dan Bird

  The company I work for sells a commercial desktop/server app that runs on any non dedicated Windows PC or server and uses Tomcat for all interactions with the application. Customers are asking that we host their instance of the application so they don't have to run it locally on their own servers. The app is lightweight and an average server, in theory, could handle 25-50 instances before users would notice a slowdown. However only 1 instance can run per Windows instance (because the application writes to a common registry branch) so we'd need something like VMWare to create 25-50 Windows instances. We know we eventually need to reprogram to make it truly cloud-worthy but what would you recommend for a server farm or whatever for this? We don't have the setup to purchase our own servers so we must use a 3rd party. We have budgeted $500 - $1000 per year per customer for this service. Thanks in advance for your suggestions, experiences and guidance.

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