Search Results

Search found 8215 results on 329 pages for 'high ball'.

Page 258/329 | < Previous Page | 254 255 256 257 258 259 260 261 262 263 264 265  | Next Page >

• Network switches for LAN party

  - by guywhoneedsahand

  I am working on setting up the network for a small LAN party (less than 16 people). Most of them do not have wireless cards in their rigs, so I need to set up some way for everyone to a) play LAN games and b) access the internet. The LAN party will probably take place in my basement, where I have enough space. However, the basement is not wired up with the router which is actually on the floor above. I make a cantenna a while back that can boost the wireless performance of my computer significantly. How can I use this to provide internet and LAN to guests? My hope was that I could use a switch like this http://www.newegg.com/Product/Product.aspx?Item=N82E16833181166 for the LAN - but how can I give people access to the internet? Is there such thing as a network extender / 16-port switch? Obviously, the internet performance doesn't need to be super stellar, because the games will be using LAN - so I am looking to provide some usable internet for web browsing, and very high speed LAN for games. Thanks!

  Read the article

• What kind of server configuration is best for a chatting app? [closed]

  - by mohabitar

  I'm just now starting to go deeper into the world of cloud hosting and databases, and am getting overwhelmed by how deep this information goes. It's all a little too much to consume in a short amount of time. I get a lot of pricing information, but I'm unable to determine what that means to me. I'm making what you might compare to an email app. Users can send messages to one another. I just don't understand, out of the several options, what would be ideal for an app like this, where users would be constantly sending and receiving text data. With Amazon DynamoDB, I have to specify a pre-defined throughput with number of reads and writes per second. Sure I can just type 50, but I'm not exactly sure what 50 writes per second represents. I'm trying to determine what would be the most cost efficient solution, and I want to know what a throughput of 50 reads/writes/second compares to. Is that a high number? What is a good throughput number for a message sending app with say 50,000 daily users? I'm just providing specific numbers so I can understand what these throughput numbers represent. 100 transactions/second to me seems like a small number since I'm not familiar with this stuff, so I'm just looking to bring everything in context. What would 100 read/write/second be useful for? Are there any average example values available? And I'm not sure what each service is good for. For a message sending app, is there any reason I'd want to choose say Amazon DynamoDB over Google App Engine? Any insight would be greatly appreciated.

  Read the article

• Encrypted Windows 7 & Linux Advice Wanted

  - by Miles

  I would like to set up my laptop to dual boot Arch Linux and Windows 7 with file sharing and encryption. Just wanted some advice on going about this because I have not dealt with encryption nor file sharing. I have two 500GB hard drives, and this is my plan: Install Windows 7 across both hard drives Use a live CD to wipe out Windows boot loader and replace with Grub Legacy Use live CD to wipe out second hard drive and re-size the Windows partition located on first hard drive Install Arch Linux along side with Windows 7 on first hard drive, all remaining space goes to home folder as ext2 Install truecrypt and ext2fsd Concerns: Is this the most efficient way to share files between both OSes? Or should I just be using NTFS to store all my data? How would the file permissions work when sharing files between Windows and Linux? Is there a high likley hood of corruption, and what is the ease of backing up files from an encrypted disk? Anything I should look out for, conflict between Grub and Truecrypt? Thank you for any advice, and feel free to post any links you might find useful to me. I am trying to plan this out so I can minimize downtime as I do not want to spend more than a night on this, nor do I want to run into a major problem some time in the future.

  Read the article

• CPU usage always below 10% in windows server 2008 r2 x64

  - by ???

  I am using a server with windows server 2008 r2 running on it to run my program. The CPU of the server is Intel xeon x5570 2.93GHz with 2 processors, 8 cores per processer. However, I found that the cpu usage is almost always below 10% even I use 32 threads in my program. And I also found that sometimes the cpu usage could reach as high as 93% through the task manager when running my program and at that moment my program has processed over 1000 files per second while normally, it only processed over 50 files per second. However, this does not happen often. I use tools downloaded from the internet to make sure no core sleeps when the server is on, nothing changed. Also, I edited the windows register to make sure that I, as an administer, have no cpu usage limit. But it changed nothing. Is there anyway that I can make full use of my cpu? That is to say that each core runs a thread of my program and the total cpu usage could reach over 50% when I use a reasonable number of threads in my program. Did this happen to anyone of you? And could you help me with this ? Thank you!

  Read the article

• Safe use of Update-FormatData?

  - by Steve B

  In a custom PowerShell module, I have at the top of my module definition this code: Update-FormatData -AppendPath (Join-Path $psscriptroot "*.ps1xml") This is working fine as all .ps1xml files are loaded. However, the module is sometimes loaded using Import-Module MyModule -Force (actually, this is in the install script of the module). In this case, the call to Update-FormatData fails with this error : Update-FormatData : There were errors in loading the format data file: Microsoft.PowerShell, c:\pathto\myfile.Types.ext.ps1xml : File skipped because it was already present from "Microsoft.PowerShell". At line:1 char:18 + Update-FormatData <<<< -AppendPath "c:\pathto\myfile.Types.ext.ps1xml" + CategoryInfo : InvalidOperation: (:) [Update-FormatData], RuntimeException + FullyQualifiedErrorId : FormatXmlUpateException,Microsoft.PowerShell.Commands.UpdateFormatDataCommand Is there a way to safely call this command? I know I can call Update-FormatData with no parameters, and it will update any known .ps1xml file, but this would work only if the file has already been loaded. Can I list somewhere the loaded format data files? Here is a bit of background: I'm building a custom module that is installed using a script. The install script looks like : [CmdletBinding(SupportsShouldProcess=$true,ConfirmImpact="High")] param() process { $target = Join-Path $PSHOME "Modules\MyModule" if ($pscmdlet.ShouldProcess("$target","Deploying MyModule module")) { if(!(Test-Path $target)) { new-Item -ItemType Directory -Path $target | Out-Null } get-ChildItem -Path (Split-Path ((Get-Variable MyInvocation -Scope 0).Value).MyCommand.Path) | copy-Item -Destination $target -Force Write-Host -ForegroundColorWhite @" The module has been installed. You can import it using : Import-Module MyModule Or you can add it in your profile ($profile) "@ Write-Warning "To refresh any open PowerShell session, you should run ""Import-Module MyModule -Force"" to reload the module" Import-Module MyModule -Force Write-Warning "This session has been refreshed." } } MyModule defines, as first statement, this line : Update-FormatData -AppendPath (Join-Path $psscriptroot "*.ps1xml") As I updated my $profile to always load this module, the Update-Path command has been called when I run the install script. In the install script, I force import the module, which be fire again the module, and then, the Update-Path call

  Read the article

• MysqlTunner and query_cache_size dilemma

  - by wbad

  On a busy mysql server MySQLTuner 1.2.0 always recommends to add query_cache_size no matter how I increase the value (I tried up to 512MB). On the other hand it warns that : Increasing the query_cache size over 128M may reduce performance Here are the last results: >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.5.25-1~dotdeb.0-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in InnoDB tables: 6G (Tables: 195) [--] Data in PERFORMANCE_SCHEMA tables: 0B (Tables: 17) [!!] Total fragmented tables: 51 -------- Security Recommendations ------------------------------------------- [OK] All database users have passwords assigned -------- Performance Metrics ------------------------------------------------- [--] Up for: 1d 19h 17m 8s (254M q [1K qps], 5M conn, TX: 139B, RX: 32B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 24.2G global + 92.2M per thread (1200 max threads) [!!] Maximum possible memory usage: 132.2G (139% of installed RAM) [OK] Slow queries: 0% (2K/254M) [OK] Highest usage of available connections: 32% (391/1200) [OK] Key buffer size / total MyISAM indexes: 128.0M/92.0K [OK] Key buffer hit rate: 100.0% (8B cached / 0 reads) [OK] Query cache efficiency: 79.9% (181M cached / 226M selects) [!!] Query cache prunes per day: 1033203 [OK] Sorts requiring temporary tables: 0% (341 temp sorts / 4M sorts) [OK] Temporary tables created on disk: 14% (760K on disk / 5M total) [OK] Thread cache hit rate: 99% (676 created / 5M connections) [OK] Table cache hit rate: 22% (1K open / 8K opened) [OK] Open file limit used: 0% (49/13K) [OK] Table locks acquired immediately: 99% (64M immediate / 64M locks) [OK] InnoDB data size / buffer pool: 6.1G/19.5G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Reduce your overall MySQL memory footprint for system stability Increasing the query_cache size over 128M may reduce performance Variables to adjust: *** MySQL's maximum memory usage is dangerously high *** *** Add RAM before increasing MySQL buffer variables *** query_cache_size (> 192M) [see warning above] The server has 76GB ram and dual E5-2650. The load is usually below 2. I appreciate your hints to interpret the recommendation and optimize the database configs.

  Read the article

• Mysqld shutting down by itself

  - by AJ Naidas

  I'm running a Wordpress Blog that gets medium-high traffic. It is hosted in an Ubuntu Server 2GB Memory 2 Core Processor 40GB SSD Disk, 3TB Transfer. The problem is that MySQL shuts down by itself after an hour or two. I had to restart mysql each and every time this happens. I checked the logs and this is what I found: 140612 6:48:14 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead. 140612 6:48:14 [Note] Plugin 'FEDERATED' is disabled. 140612 6:48:14 InnoDB: The InnoDB memory heap is disabled 140612 6:48:14 InnoDB: Mutexes and rw_locks use GCC atomic builtins 140612 6:48:14 InnoDB: Compressed tables use zlib 1.2.3.4 140612 6:48:14 InnoDB: Initializing buffer pool, size = 1.4G InnoDB: mmap(1502412800 bytes) failed; errno 12 140612 6:48:14 InnoDB: Completed initialization of buffer pool 140612 6:48:14 InnoDB: Fatal error: cannot allocate memory for the buffer pool 140612 6:48:14 [ERROR] Plugin 'InnoDB' init function returned error. 140612 6:48:14 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 140612 6:48:14 [ERROR] Unknown/unsupported storage engine: InnoDB 140612 6:48:14 [ERROR] Aborting 140612 6:48:14 [Note] /usr/sbin/mysqld: Shutdown complete judging by this line: 140612 6:48:14 InnoDB: Fatal error: cannot allocate memory for the buffer pool I suspect that this is a memory problem, but I would like to hear from the experts here before I conclude. Is this a lack of memory problem? Do you think the value of max_connections in my.cnf (currently 100) is a potential cause and needs increasing? TIA.

  Read the article

• Matched or unmatched drives for RAID arrays?

  - by Will

  Looking around there is conflciting information on this, with some strongly suggesting one or the other. From my understanding the issue with matched drives is that the wear on both drives is more or less the same, so the potential for the second drive failing with or very soon after the first is pretty high. People also claim matched drives give substianatally higher performance however assuming the unmatched drives are more or less the same (eg 2, 1 TB STATA II 7200rpm drives with 32MB cache), would the minor differences between say a Seagate and a Western Digital one (say one has a 128MB/s read rate, and the other a 150MB/s read rate, as well as I guess various other minor differences) actually cause any notable performance loss, ie potentialy worse than two matched 128MB/s drives, or does RAID not really care and give you essentially an optimal solution (eg upto 278MB/s total read speed for RAID 0 and 1) and similar for other RAID with more "unmatched" drives (5 and 1+0 come to mind as possibilities)? Also I couldnt find much info on how this is different on different RAID setups, eg RAID 0 or RAID 1, software or hardware RAID, etc. I'm assuming such things have an effect, and thats it's not all the same for RAID in general?

  Read the article

• VM load and ping problems after replacing server motherboard

  - by Andre

  Recently, we had to replace the motherboard of one of our servers. The procedure was done by IBM as it had guarantee. The server runs ESXi 5.1, with several virtual machines, including our main mail server (Domino) and a file server. After the replacing the motherboard and staring the VMs, ESXi asked us if we had moved it or copied (different motherboard is like a different computer). We clicked the latter. We started each machine and after some basic reconfiguration, all of them were up. However, we have been having problems with the mail server, it has been acting really slow at times (this could be when it syncs with the secondary mail server) and we have been checking with Centreon (a Nagios frontend) that its CPU load has been a bit high at times and ping response too. There was a moment this morning in which I tried connecting via SSH console and it was really slow to show login and basic commands like ifconfig and top. This particular mail server is a CentOS 4.4.7 64-bit. The little configuring we had to do after restarting it was to configure the network connection as it was resolving through DHCP. Our mail software is Lotus Notes server 9. Do you know of any way in which this replacement may be causing these difficulties, and how to fix it? Thanks.

  Read the article

• How can I prevent a DDOS attack on Amazon EC2?

  - by cwd

  One of the servers I use is hosted on the Amazon EC2 cloud. Every few months we appear to have a DDOS attack on this sever. This slows the server down incredibly. After around 30 minutes, and sometimes a reboot later, everything is back to normal. Amazon has security groups and firewall, but what else should I have in place on an EC2 server to mitigate or prevent an attack? From similar questions I've learned: Limit the rate of requests/minute (or seconds) from a particular IP address via something like IP tables (or maybe UFW?) Have enough resources to survive such an attack - or - Possibly build the web application so it is elastic / has an elastic load balancer and can quickly scale up to meet such a high demand) If using mySql, set up mySql connections so that they run sequentially so that slow queries won't bog down the system What else am I missing? I would love information about specific tools and configuration options (again, using Linux here), and/or anything that is specific to Amazon EC2. ps: Notes about monitoring for DDOS would also be welcomed - perhaps with nagios? ;)

  Read the article

• Find which files an apache process is writing to?

  - by Haluk

  We have this apache process which becomes io-bound time to time. Using atop, we can see it is a write operation. Using lsof -p <PID> we can see a list of files open by the httpd process. First we thought "log" files must be the problem. So we turned them off just to test. However write operations still continues. We will continue testing a few other things. For instance we use php session variables a lot. Maybe php session files are getting all the writing. But is there a way to quickly identify files which get written to by the httpd process? This way we can focus our efforts on those files. UPDATE: We used the strace command as suggested. Here are two lines from the output. write(23, "\27\0\0\0\3SET CHARACTER SET utf8", 27) = 27 write(23, "\17\0\0\0\3SET NAMES utf8", 19) = 19 We do not have a mysql process on this server. So is strace also showing what is being written to an ethernet port? UPDATE2: During high io load, the process which consumes most of the write resources gives the following output to strace -e trace=write -p <PID>: --- SIGCHLD (Child exited) @ 0 (0) --- write(9, "!", 1) = 1 write(19, "OPTIONS * HTTP/1.0\r\nUser-Agent: Apache (internal dummy connection)\r\n\r\n", 70) = 70 However I cannot figure out where these are being written to.

  Read the article

• VLC Crash when playing MKV files in Windows 7

  - by Phelios

  I'm not sure if the mkv file is corrupted, but when it is opened with VLC player, VLC loads up and displays nothing. Can't even close VLC after that. And also, VLC is running with 50% of the CPU. I have to use End Process to kill it. How do I know if the file is corrupted? How do I solve this? info from mediainfo Format : Matroska File size : 69.4 MiB Duration : 21mn 48s Overall bit rate : 445 Kbps Encoded date : UTC 2009-11-20 18:33:49 Writing application : mkvmerge v2.9.7 ('Tenderness') built on Jul 1 2009 18:43:35 Writing library : libebml v0.7.7 + libmatroska v0.8.1 Video ID : 1 Format : AVC Format/Info : Advanced Video Codec Format profile : [email protected] Format settings, CABAC : Yes Format settings, ReFrames : 2 frames Format settings, GOP : N=1 Codec ID : V_MPEG4/ISO/AVC Duration : 21mn 48s Width : 640 pixels Height : 352 pixels Display aspect ratio : 16:9 Frame rate : 23.976 fps Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Audio ID : 2 Format : AAC Format/Info : Advanced Audio Codec Format profile : HE-AAC / LC Codec ID : A_AAC Duration : 21mn 48s Channel(s) : 2 channels Channel positions : Front: L R Sampling rate : 48.0 KHz / 24.0 KHz Compression mode : Lossy

  Read the article

• What are the typical methods used to scale up/out email storage servers?

  - by nareshov

  Hi, What I've tried: I have two email storage architectures. Old and new. Old: courier-imapds on several (18+) 1TB-storage servers. If one of them show signs of running out of disk space, we migrate a few email accounts to another server. the servers don't have replicas. no backups either. New: dovecot2 on a single huge server with 16TB (SATA) storage and a few SSDs we store fresh mails on the SSDs and run a doveadm purge to move mails older than a day to the SATA disks there is an identical server which has a max-15min-old rsync backup from the primary server higher-ups/management wanted to pack in as much storage as possible per server in order to minimise the cost of SSDs per server the rsync'ing is done because GlusterFS wasn't replicating well under that high small/random-IO. scaling out was expected to be done with provisioning another pair of such huge servers on facing disk-crunch issues like in the old architecture, manual moving of email accounts would be done. Concerns/doubts: I'm not convinced with the synchronously-replicated filesystem idea works well for heavy random/small-IO. GlusterFS isn't working for us yet, I'm not sure if there's another filesystem out there for this use case. The idea was to keep identical pairs and use DNS round-robin for email delivery and IMAP/POP3 access. And if one the servers went down for whatever reasons (planned/unplanned), we'd move the IP to the other server in the pair. In filesystems like Lustre, I get the advantage of a single namespace whereby I do not have to worry about manually migrating accounts around and updating MAILHOME paths and other metadata/data. Questions: What are the typical methods used to scale up/out with the traditional software (courier-imapd / dovecot)? Do traditional software that store on a locally mounted filesystem pose a roadblock to scale out with minimal "problems"? Does one have to re-write (parts of) these to work with an object-storage of some sort - such as OpenStack object storage?

  Read the article

• Backtrack, Wi-Fi not working

  - by hradecek

  I've installed Backtrack 5R3 KDE, and I realized that my wireless is not working, but wired is working fine. Here's the lshw output: *-network description: Ethernet interface product: RTL8101E/RTL8102E PCI Express Fast Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: 05 serial: 04:7d:7b:b7:46:f8 size: 100MB/s capacity: 100MB/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8105e-1.fw ip=192.168.2.2 latency=0 link=yes multicast=yes port=MII speed=100MB/s resources: irq:42 ioport:2000(size=256) memory:f0404000-f0404fff memory:f0400000-f0403fff lspci output: 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:14.0 USB Controller: Intel Corporation Panther Point USB xHCI Host Controller (rev 04) 00:16.0 Communication controller: Intel Corporation Panther Point MEI Controller #1 (rev 04) 00:1a.0 USB Controller: Intel Corporation Panther Point USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 1 (rev c4) 00:1c.1 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 2 (rev c4) 00:1d.0 USB Controller: Intel Corporation Panther Point USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Panther Point LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation Panther Point 6 port SATA AHCI Controller (rev 04) 00:1f.3 SMBus: Intel Corporation Panther Point SMBus Controller (rev 04) 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 05)

  Read the article

• New to server admin, Diagnosing Memory and CPU issues on DV

  - by G Thompson

  Sorry for my ignorance and lack of knowledge. I'm a PHP/Front-end developer just now venturing into very minor server management/diagnostics. I have a Media Temple DV account. I have 2 sites that run a PHP script through a subscription service to an API. Basically API hits site with said script. Script runs, gathers data from api, saves data to SQL database. I noticed that these sites seemed to causing memory overages on my server (not sure why). So I temporarily disabled them. The memory overage alerts stopped but my CPU still sits really high, like at 115% and above. I'm trying to diagnos this with tutorials and resources but just can't seem to find a solution. I'll attach screenshots(screenshots are without the PHP scripts I assume are responsible for the memory issues) I'm assuming are important to the diagnosis, but if anyone can point me in the right direction to start A. figuring out if and why the PHP script may be causing memory overages and B. Why my CPU is always over 100%. Thanks guys! Links to screen shots... can't post with low points. http://i.stack.imgur.com/A64k4.png http://i.stack.imgur.com/qm1rV.png

  Read the article

• Switched to new router and now experiencing lag?

  - by Mr_CryptoPrime

  I switched from a dynex-802.11b/g to a Netgear-802.11b/g/n just yesterday. My router is down stairs because my phoneline upstairs is retarded....but my PS3 is still upstairs (SOCOM: Confrontation is game I am experiencing issues). I have done everything I can to make sure the connection is solid and have checked the status and it has been as high as 80% and usually lingers at about 60%. I thought about upgrading my bandwidth from 1.5mbs to 7mbs, but I am guessing something is wrong if it worked fine before? Now the game seems more laggy and my voice chat is choppy. Others seem to receive my voice data fine because I can hear my own feedback clearly from other players (if you are in close proximity to another player and speak and there volume is loud enough sometimes you can hear yourself). I wonder if I port forward or setup DMZ then it will be fixed, but I am not sure and don't know quite how to do it. Has anyone else ever experienced this when switching routers? What did you do to fix it? Thanks!

  Read the article

• MySQL Memory Limit Windows Server 2003

  - by Matt

  I am running MySQL 5.0.51a on Windows Server 2003 Standard Edition on an HP DL580 G4 with 3GB installed. One of my database tables has grown to 5.3 GB with an index file of 2.5 GB, which I believe is causing MySQL to be slow due to having to constantly load and unload the index file when updates are made to the table. The server itself seems to be performing OK because MySQL is only using about 500MB of memory (there are other apps running on the system, but MySQL uses the most memory). The table is fairly active with new records getting adding all during day but no deletes, ever. The MySQL server has up to 600 connections allowed, but only small number (10 or 20) would actually be writing to this table. I increased the memory limits in MySQL but since the max connections is so high I don't think I can give each connection 1GB without risking a problem. Is there some tuning that would let just certain connections get a lot of memory? So I have started to look for alternatives to avert the crisis I know is coming soon. Some of the options I have: Upgrade to Server 2003 Enterprise to install 64GB of memory. Question: would 32 bit MySQL be able to access more than 2GB? Would that be 2GB per thread? That would still be smaller than the index table size so it might not solve the problem completely, but it would be better than now. Upgrade to Server 200x 64 bit and MySQL 64 bit. Switch to a *nix 64 bit server. If anybody has suggestions for things to do in the meantime, opinions on which way to go, or other things that I have overlooked I would appreciate the help. Thanks

  Read the article

• Linux iptables / conntrack performance issue

  - by tim

  I have a test-setup in the lab with 4 machines: 2 old P4 machines (t1, t2) 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t3) Intel e1000 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t4) Intel e1000 to test linux firewall performance since we got bitten by a number of syn-flood attacks in the last months. All machines run Ubuntu 12.04 64bit. t1, t2, t3 are interconnected through an 1GB/s switch, t4 is connected to t3 via an extra interface. So t3 simulates the firewall, t4 is the target, t1,t2 play the attackers generating a packetstorm thorugh (192.168.4.199 is t4): hping3 -I eth1 --rand-source --syn --flood 192.168.4.199 -p 80 t4 drops all incoming packets to avoid confusion with gateways, performance issues of t4 etc. I watch the packet stats in iptraf. I have configured the firewall (t3) as follows: stock 3.2.0-31-generic #50-Ubuntu SMP kernel rhash_entries=33554432 as kernel parameter sysctl as follows: net.ipv4.ip_forward = 1 net.ipv4.route.gc_elasticity = 2 net.ipv4.route.gc_timeout = 1 net.ipv4.route.gc_interval = 5 net.ipv4.route.gc_min_interval_ms = 500 net.ipv4.route.gc_thresh = 2000000 net.ipv4.route.max_size = 20000000 (I have tweaked a lot to keep t3 running when t1+t2 are sending as many packets as possible). The result of this efforts are somewhat odd: t1+t2 manage to send each about 200k packets/s. t4 in the best case sees aroung 200k in total so half of the packets are lost. t3 is nearly unusable on console though packets are flowing through it (high numbers of soft-irqs) the route cache garbage collector is no way near to being predictable and in the default setting overwhelmed by very few packets/s (<50k packets/s) activating stateful iptables rules makes the packet rate arriving on t4 drop to around 100k packets/s, efectively losing more than 75% of the packets And this - here is my main concern - with two old P4 machines sending as many packets as they can - which means nearly everyone on the net should be capable of this. So here goes my question: Did I overlook some importand point in the config or in my test setup? Are there any alternatives for building firewall system especially on smp systems?

  Read the article

• I need to build a mini computer lab with 6 PCs

  - by chiurox

  Hello everyone, This weekend I need to build a mini computer lab with 5-6 PCs. The purpose is for a small computer class that will be taking place. They're mostly going to be doing office and daily kind of stuff, so nothing high performance. However, I hope it will last at least for 2 more years. I already have some parts for 2 PCs, one is a P4 3.0 and another is Celeron 2.4GHz, both socket 478. For the other 4 PCs, I'm wondering if I should buy individual parts and put it all together or get workstations like those Dell Optiplex with P4s. To put things into perspective, I am not currently in the US. I'm in South America and prices here are ridiculously. Another really important thing is that I need to share an internet connection between a total of 8 PCs at this place. Right now I only have a crappy wireless router, should I get another one? Or go with switch hub? I'm not experienced in this matter. Thanks guys!

  Read the article

• How to set an executable white list?

  - by izabera

  Under Linux, is it possible to set a white-list of executables for a certain group of users? I need them to be unable to use, for example, make, gcc and executables on removable disks. How can this be done? Edit, let me explain better. I'm dealing with a high school IT system, young geeks that (during the lessons) want to play, surf the net, damage those computer however they can. The major step to achieve this goal was to remove the system they're familiar with and install Ubuntu in all the computers. This actually works quite well, but recent events proved that this is not enough. I want to allow them to execute certain safe programs, like Open Office, and to deny any other program, whether it is preinstalled software, something they carry in usb drives, a downloaded program or a script they program on site. It's possible to remove the 'x' permission on any file on the pc, but of course it would be impractical. Furthermore, they would be able to run anything they download. I thought the best solution would be to make a white-list of safe programs and to deny anything else, but I don't really know how to do it. Any idea is helpful.

  Read the article

• 3dmark score abnormal

  - by Sean

  I just bought a new laptop. It is core i7 3610QM.(Ivy bridge, 4 core plus hyperthreading), 8G ram, nvidia GT 610M 2GB. The OS is Win7 64bit. I ran 3dmark 11, but the score is frustrating. For 1280*720, the score is P730. It is too low right? I searched online, the score should at least above 1000. Am I right? I never use this software before. I know nvidia has optimus, so I made the laptop in high performance state and white-listed the 3dmark program. But there is no help. I am guessing 3dmark is using i7's graphic module. It cannot transform to nvidia. In the running detail of 3dmark, the graphic card cannot be identified(The row remain blank). Can anybody tell me is this the normal case? If not, can I use some other software to test if my nvidia card is working fine? If this nvidia card cannot work, I will return the new laptop asap. Thanks.

  Read the article

• Is my "Generic" USB Flash Drive broken?

  - by Jesse J.

  So here is the situation. I find myself technological knowledgeable about many things ( I love to code, whether it's websites, C#, C++ or so on). However: My 2 toddlers (my wife actually) bought me a "Generic" 128 GB USB Storage Device (Usb Flash Drive) for Father's Day. I thought awesome at first..... WRONG! Nothing but problems with it. 3-4mb/s MAX transfer speed. I can bear with it. BUT! When I went to reformat my computer I transferred my save files from my games over to the stick and then the USB Stick managed to become corrupted. Not just a simple format would work either. It's screwed. I tried to use (Manually changed usb drive letter troubleshooting it to X) "chmod X: /X /F /R" with administrator rights, I did this after a long session to make it work with no errors (had to delete the log) and I finally recovered the files, however when I go to use it (transfer to or from) it transfers a couple kb to the stick or from it and then freezes, It says (Windows 7): Name: From: Folder (X:\File\Location) To: Folder C:\Users\Username\Desktop) Items Remaining: 0 (0 bytes) Speed: 0 bytes/second It does this forever... and ever... and ever... It transfered 3 files atleast, and then stopped. This is a new USB Stick bought from a "High" reputation company on eBay. Is the USB Stick screwed?

  Read the article

• Why am I unable to mount my USB drive (unknown partition table)?

  - by Pat

  I'm a real newbie to linux. Anyway the problem is that my USB doesn't get recognized anymore which is really annoying because I need information from it. I've read like a zillion threads how to manually mount it but I really can't it to work. I hope it's just some easy, stupid problem where any of you could help me out quickly.. Here is the syslog: kernel: [ 6872.420125] usb 2-2: new high-speed USB device number 11 using ehci_hcd mtp-probe: checking bus 2, device 11: "/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-2" kernel: [ 6872.556295] scsi8 : usb-storage 2-2:1.0 mtp-probe: bus: 2, device: 11 was not an MTP device kernel: [ 6873.558081] scsi 8:0:0:0: Direct-Access SanDisk Cruzer 8.01 PQ: 0 ANSI: 0 CCS kernel: [ 6873.559964] sd 8:0:0:0: Attached scsi generic sg3 type 0 kernel: [ 6873.562833] sd 8:0:0:0: [sdc] 15682559 512-byte logical blocks: (8.02 GB/7.47 GiB) kernel: [ 6873.564867] sd 8:0:0:0: [sdc] Write Protect is off kernel: [ 6873.564878] sd 8:0:0:0: [sdc] Mode Sense: 45 00 00 08 kernel: [ 6873.565485] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.565495] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.568377] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.568387] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.574330] sdc: unknown partition table kernel: [ 6873.576853] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.576863] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.576871] sd 8:0:0:0: [sdc] Attached SCSI removable disk Thanks in advance

  Read the article

• connections in FIN_WAIT and CLOSE_WAIT state

  - by Raj

  I would like to elaborate the setup so You guys can understand the question and answer more accurately. I have HAProxy as load-balancer, 4 webservers (apache 2.2.3) and one database server (MySQL 5). I am monitoring these servers by nagios. I have disabled the keepalive on apache as we have only 8GB of memory. Now what happens whenever I receive alerts for high memory and cpu utilization, I have observed that the connections from apache to database server hang in established mode (keepalive with timeout value of 7200) and at other side means connections between haproxy and apache shows status as FIN_WAIT on haproxy server and CLOSE_WAIT at apache side. I also see the huge memory swapping and apache taking the most of the memory. I did strace on apache process and did not find any information. strace gets attached to apache process but did not produce any output. The processlist on Mysql server show s those processes in sleep mode. The application on webserver is Magento a php application. if you need further information please let me know. Thanks.

  Read the article

• Why does my ftp(e)s server fails like half of the time

  - by user1092608

  I have this discussion at work regarding our ftp server running via vsftpd. Initially, we have opted to serve ftpes instead of sftp because this seemed the most flexible and straightforward solution for our server to have secure file transmission. Afterwards, our ftp server seems to be a source of issues for our end users. Half of the time, users complain about not working ftp connections. I must say, i tested our FTP trough different infrastructures (=in the field, at random times at random places) and indeed, sometimes behind some configurations (=no idea how they are configured, because the 'field' testing), i recieve errors. Some of the are: Error: Failed to retrieve directory listing (filezilla) Furthermore, behind my basic home configuration, everything seems to be running fine. I (think I) did all the basic configuration checks (passive mode?, firewall for all ports?, ...) and can't seem to find the source. Being a bunch of techies at our small office, yet knowing nothing about infrastructure, some start suggesting that ftps protocol could be the source of issues. ("No, i only knew sftp so far" "Ftps is not widespread"). I, however, strongly doubt this hypothesis, since reading around on the www, asking questions on serverfault, everyone seems to deny this. So, as I would like to avoid reconfiguring, since this involves messing around in our SSH service, our virtual user setup and ftp service, i would need some advice on 1) what could be potentially the general cause? 2) do you have some general tips? 3) would you mind having a look at my configuration file? ----- General Settings ----- write_enable=YES dirmessage_enable=YES nopriv_user=ftpsecure ftpd_banner="Welcome to XXXX FTP!" hide_ids=YES hide_file=.* max_per_ip=10 max_clients=10 local_enable=YES local_umask=022 chroot_local_user=YES secure_chroot_dir=/usr/share/empty userlist_enable=NO userlist_deny=YES userlist_file=/etc/vsftp_deny_users guest_enable=YES guest_username=ftpvirtual virtual_use_local_privs=YES user_sub_token=$USER local_root=/srv/ftp/ftpvirtual/$USER anonymous_enable=NO syslog_enable=NO xferlog_enable=YES xferlog_file=/var/log/vsftpd_xfer.log connect_from_port_20=YES pam_service_name=vsftpd listen=YES listen_port=21 pasv_enable=YES pasv_min_port=30000 pasv_max_port=30030 pasv_address=foo ssl_enable=YES rsa_cert_file=/etc/vsftpd.pem rsa_private_key_file=/etc/vsftpd.pem force_local_data_ssl=YES force_local_logins_ssl=YES ssl_tlsv1=YES ssl_sslv2=YES ssl_sslv3=YES ssl_ciphers=HIGH anon_mkdir_write_enable=NO anon_root=/srv/ftp anon_upload_enable=NO idle_session_timeout=900 log_ftp_protocol=NO dsa_cert_file=/etc/vsftpd.pem Thanks

  Read the article

< Previous Page | 254 255 256 257 258 259 260 261 262 263 264 265  | Next Page >