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• Inbound SIP calls through Cisco 881 NAT hang up after a few seconds

  - by MasterRoot24

  I've recently moved to a Cisco 881 router for my WAN link. I was previously using a Cisco Linksys WAG320N as my modem/router/WiFi AP/NAT firewall. The WAG320N is now running in bridged mode, so it's simply acting as a modem with one of it's LAN ports connected to FE4 WAN on my Cisco 881. The Cisco 881 get's a DHCP provided IP from my ISP. My LAN is part of default Vlan 1 (192.168.1.0/24). General internet connectivity is working great, I've managed to setup static NAT rules for my HTTP/HTTPS/SMTP/etc. services which are running on my LAN. I don't know whether it's worth mentioning that I've opted to use NVI NAT (ip nat enable as opposed to the traditional ip nat outside/ip nat inside) setup. My reason for this is that NVI allows NAT loopback from my LAN to the WAN IP and back in to the necessary server on the LAN. I run an Asterisk 1.8 PBX on my LAN, which connects to a SIP provider on the internet. Both inbound and outbound calls through the old setup (WAG320N providing routing/NAT) worked fine. However, since moving to the Cisco 881, inbound calls drop after around 10 seconds, whereas outbound calls work fine. The following message is logged on my Asterisk PBX: [Dec 9 15:27:45] WARNING[27734]: chan_sip.c:3641 retrans_pkt: Retransmission timeout reached on transmission [email protected] for seqno 1 (Critical Response) -- See https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions Packet timed out after 6528ms with no response [Dec 9 15:27:45] WARNING[27734]: chan_sip.c:3670 retrans_pkt: Hanging up call [email protected] - no reply to our critical packet (see https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions). (I know that this is quite a common issue - I've spend the best part of 2 days solid on this, trawling Google.) I've done as I am told and checked https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions. Referring to the section "Other SIP requests" in the page linked above, I believe that the hangup to be caused by the ACK from my SIP provider not being passed back through NAT to Asterisk on my PBX. I tried to ascertain this by dumping the packets on my WAN interface on the 881. I managed to obtain a PCAP dump of packets in/out of my WAN interface. Here's an example of an ACK being reveived by the router from my provider: 689 21.219999 193.x.x.x 188.x.x.x SIP 502 Request: ACK sip:[email protected] | However a SIP trace on the Asterisk server show's that there are no ACK's received in response to the 200 OK from my PBX: http://pastebin.com/wwHpLPPz In the past, I have been strongly advised to disable any sort of SIP ALGs on routers and/or firewalls and the many posts regarding this issue on the internet seem to support this. However, I believe on Cisco IOS, the config command to disable SIP ALG is no ip nat service sip udp port 5060 however, this doesn't appear to help the situation. To confirm that config setting is set: Router1#show running-config | include sip no ip nat service sip udp port 5060 Another interesting twist: for a short period of time, I tried another provider. Luckily, my trial account with them is still available, so I reverted my Asterisk config back to the revision before I integrated with my current provider. I then dialled in to the DDI associated with the trial trunk and the call didn't get hung up and I didn't get the error above! To me, this points at the provider, however I know, like all providers do, will say "There's no issues with our SIP proxies - it's your firewall." I'm tempted to agree with this, as this issue was not apparent with the old WAG320N router when it was doing the NAT'ing. I'm sure you'll want to see my running-config too: ! ! Last configuration change at 15:55:07 UTC Sun Dec 9 2012 by xxx version 15.2 no service pad service tcp-keepalives-in service tcp-keepalives-out service timestamps debug datetime msec localtime show-timezone service timestamps log datetime msec localtime show-timezone no service password-encryption service sequence-numbers ! hostname Router1 ! boot-start-marker boot-end-marker ! ! security authentication failure rate 10 log security passwords min-length 6 logging buffered 4096 logging console critical enable secret 4 xxx ! aaa new-model ! ! aaa authentication login local_auth local ! ! ! ! ! aaa session-id common ! memory-size iomem 10 ! crypto pki trustpoint TP-self-signed-xxx enrollment selfsigned subject-name cn=IOS-Self-Signed-Certificate-xxx revocation-check none rsakeypair TP-self-signed-xxx ! ! crypto pki certificate chain TP-self-signed-xxx certificate self-signed 01 quit no ip source-route no ip gratuitous-arps ip auth-proxy max-login-attempts 5 ip admission max-login-attempts 5 ! ! ! ! ! no ip bootp server ip domain name dmz.merlin.local ip domain list dmz.merlin.local ip domain list merlin.local ip name-server x.x.x.x ip inspect audit-trail ip inspect udp idle-time 1800 ip inspect dns-timeout 7 ip inspect tcp idle-time 14400 ip inspect name autosec_inspect ftp timeout 3600 ip inspect name autosec_inspect http timeout 3600 ip inspect name autosec_inspect rcmd timeout 3600 ip inspect name autosec_inspect realaudio timeout 3600 ip inspect name autosec_inspect smtp timeout 3600 ip inspect name autosec_inspect tftp timeout 30 ip inspect name autosec_inspect udp timeout 15 ip inspect name autosec_inspect tcp timeout 3600 ip cef login block-for 3 attempts 3 within 3 no ipv6 cef ! ! multilink bundle-name authenticated license udi pid CISCO881-SEC-K9 sn ! ! username xxx privilege 15 secret 4 xxx username xxx secret 4 xxx ! ! ! ! ! ip ssh time-out 60 ! ! ! ! ! ! ! ! ! interface FastEthernet0 no ip address ! interface FastEthernet1 no ip address ! interface FastEthernet2 no ip address ! interface FastEthernet3 switchport access vlan 2 no ip address ! interface FastEthernet4 ip address dhcp no ip redirects no ip unreachables no ip proxy-arp ip nat enable duplex auto speed auto ! interface Vlan1 ip address 192.168.1.1 255.255.255.0 no ip redirects no ip unreachables no ip proxy-arp ip nat enable ! interface Vlan2 ip address 192.168.0.2 255.255.255.0 ! ip forward-protocol nd ip http server ip http access-class 1 ip http authentication local ip http secure-server ip http timeout-policy idle 60 life 86400 requests 10000 ! ! no ip nat service sip udp port 5060 ip nat source list 1 interface FastEthernet4 overload ip nat source static tcp x.x.x.x 80 interface FastEthernet4 80 ip nat source static tcp x.x.x.x 443 interface FastEthernet4 443 ip nat source static tcp x.x.x.x 25 interface FastEthernet4 25 ip nat source static tcp x.x.x.x 587 interface FastEthernet4 587 ip nat source static tcp x.x.x.x 143 interface FastEthernet4 143 ip nat source static tcp x.x.x.x 993 interface FastEthernet4 993 ip nat source static tcp x.x.x.x 1723 interface FastEthernet4 1723 ! ! logging trap debugging logging facility local2 access-list 1 permit 192.168.1.0 0.0.0.255 access-list 1 permit 192.168.0.0 0.0.0.255 no cdp run ! ! ! ! control-plane ! ! banner motd Authorized Access only ! line con 0 login authentication local_auth length 0 transport output all line aux 0 exec-timeout 15 0 login authentication local_auth transport output all line vty 0 1 access-class 1 in logging synchronous login authentication local_auth length 0 transport preferred none transport input telnet transport output all line vty 2 4 access-class 1 in login authentication local_auth length 0 transport input ssh transport output all ! ! end ...and, if it's of any use, here's my Asterisk SIP config: [general] context=default ; Default context for calls allowoverlap=no ; Disable overlap dialing support. (Default is yes) udpbindaddr=0.0.0.0 ; IP address to bind UDP listen socket to (0.0.0.0 binds to all) ; Optionally add a port number, 192.168.1.1:5062 (default is port 5060) tcpenable=no ; Enable server for incoming TCP connections (default is no) tcpbindaddr=0.0.0.0 ; IP address for TCP server to bind to (0.0.0.0 binds to all interfaces) ; Optionally add a port number, 192.168.1.1:5062 (default is port 5060) srvlookup=yes ; Enable DNS SRV lookups on outbound calls ; Note: Asterisk only uses the first host ; in SRV records ; Disabling DNS SRV lookups disables the ; ability to place SIP calls based on domain ; names to some other SIP users on the Internet ; Specifying a port in a SIP peer definition or ; when dialing outbound calls will supress SRV ; lookups for that peer or call. directmedia=no ; Don't allow direct RTP media between extensions (doesn't work through NAT) externhost=<MY DYNDNS HOSTNAME> ; Our external hostname to resolve to IP and be used in NAT'ed packets localnet=192.168.1.0/24 ; Define our local network so we know which packets need NAT'ing qualify=yes ; Qualify peers by default dtmfmode=rfc2833 ; Set the default DTMF mode disallow=all ; Disallow all codecs by default allow=ulaw ; Allow G.711 u-law allow=alaw ; Allow G.711 a-law ; ---------------------- ; SIP Trunk Registration ; ---------------------- ; Orbtalk register => <MY SIP PROVIDER USER NAME>:[email protected]/<MY DDI> ; Main Orbtalk number ; ---------- ; Trunks ; ---------- [orbtalk] ; Main Orbtalk trunk type=peer insecure=invite host=sipgw3.orbtalk.co.uk nat=yes username=<MY SIP PROVIDER USER NAME> defaultuser=<MY SIP PROVIDER USER NAME> fromuser=<MY SIP PROVIDER USER NAME> secret=xxx context=inbound I really don't know where to go with this. If anyone can help me find out why these calls are being dropped off, I'd be grateful if you could chime in! Please let me know if any further info is required.

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• Get CLSID by PIA interface Type

  - by Charles

  How can I get the CLSID for a given interface within a Primary Interop Assembly? Here's what I'm talking about: // The c# compiler does some interesting magic. // The following code ... var app = new Microsoft.Office.Interop.Outlook.Application(); // ... is compiled like so (disassembled with Reflector): var app =((Microsoft.Office.Interop.Outlook.Application) Activator.CreateInstance(Type.GetTypeFromCLSID(new Guid("0006F03A-0000-0000-C000-000000000046")))); Microsoft.Office.Interop.Outlook.Application is an interface, and therefore it cannot be instantiated directly. What's interesting here is that c# lets you treat these COM interfaces as if there where classes that you can instantiate with the new keyword. What I want to know is, given the System.Type for a given interface, how can I get the CLSID? Note: I ultimately want to be able to create an instance given the interface's System.Type - I don't really care how. I'm assuming here that the easiest way to do this would be to get CLSID given the Type, just as the c# compiler does.

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• AJAX Partial page update problem when displaying a control

  - by Jernej Goricki

  Hello! I have an interesting problem when using partial page update in asp.net with scriptmanager and a update panel. My scenario looks like this: I'm using the tab control from the ajax toolkit. I also implemented this control using lazy loading, so that when the page is loaded only the current tab gets loaded all the other tabs don't get rendered, because Im using an UpdatePanel (on a .ascx control) on each of these tabs and when a tab gets selected the updatepanel makes a async postback to load the content for a selected tab. On one of my tabs Im using a combobox control from obout.com, and it doesn't work. Now I know why it doesn't work. It doesn't work because the control is shown via a partial page refresh, but to correctly display the control it has to do some "magic" that is - register some .css and .js includes on the page (in the head I guess)....but because I load this control via async page refresh...it can't do these stuff. What kind of workarround do you suggest? Thanks!

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• Kunagi LDAP configuration problems

  - by Willem de Vries

  We recently started with Scrum at our company and we wanted to start using Kunagi to test and see how it works. So I installed the kunagi_0.23.2.deb packet that I downloaded from their website, on my Ubuntu 11.04 running in tomcat6 using openjdk-6-jre. everything works fine except I can't get the LDAP to work. I have one AD server and one LDAP at my disposal for testing. For the LDAP I use the following info: -uri: ldap://192.168.1.11:389 -user: some_tested_user -passwd: the_pass -DN: dc=colosa,dc=net -LDAP Filter: (&(objectClass=user)) I tested various LDAP Filters, I don't know if I have the right one. However I get an erro when clicking "test LDAP". The error refers to the DN: Server service call error Calling service TestLdap failed. java.lang.RuntimeException: InvalidNameException: [LDAP: error code 34 - invalid DN] With the AD server I get no error while testing, yet I am not able to login I get: "Login faild" every time. I don't know if this is because of the LDAP Filter I entered, yet I can't get it to work. I have read this http://kunagi.org/iss652.html stating that I need to create my accounts inside Kunagi before I can login. So I did this with no effect. So basically my question is, what causes this DN string error (I am sure mine is right), and what LDAP Filter should i use? Any help would be highly appreciated.

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• need to stop mysql server on my mac os x

  - by al0ne evenings

  I just installed xampp on my mac os x. When I tried start mysql it display a message that mysql is already running on this computer. In order to start mysql stop first mysql. I tried following ways to stop it but neither of them works. mysqladmin version sudo /usr/local/mysql/mysql.server stop //mysql.server command not found mysqladmin -u root -p password shutdown //restarts the server but not shutdown when i use which mysql command it shows this path /usr/local/bin/mysql and when I issue ps aux | grep mysqld command I get following output zafarsaleem 85209 0.0 0.3 2699804 13204 ?? S 7:51AM 0:00.88 /Applications/MAMP/Library/bin/mysqld --basedir=/Applications/MAMP/Library --datadir=/Applications/MAMP/db/mysql --plugin-dir=/Applications/MAMP/Library/lib/plugin --lower-case-table-names=0 --log-error=/Applications/MAMP/logs/mysql_error_log.err --pid-file=/Applications/MAMP/tmp/mysql/mysql.pid --socket=/Applications/MAMP/tmp/mysql/mysql.sock --port=8889 zafarsaleem 85093 0.0 0.0 2435488 924 ?? S 7:51AM 0:00.03 /bin/sh /Applications/MAMP/Library/bin/mysqld_safe --port=8889 --socket=/Applications/MAMP/tmp/mysql/mysql.sock --lower_case_table_names=0 --pid-file=/Applications/MAMP/tmp/mysql/mysql.pid --log-error=/Applications/MAMP/logs/mysql_error_log zafarsaleem 86693 0.0 0.0 2425480 180 s004 R+ 8:30AM 0:00.00 grep mysqld zafarsaleem 86507 0.0 0.3 2678756 11364 ?? S 8:07AM 0:00.63 /usr/local/Cellar/mysql/5.5.20/bin/mysqld --basedir=/usr/local/Cellar/mysql/5.5.20 --datadir=/usr/local/var/mysql --plugin-dir=/usr/local/Cellar/mysql/5.5.20/lib/plugin --max-allowed-packet=32M --log-error=/usr/local/var/mysql/Zafars-MacBook-Pro-2.local.err --pid-file=/usr/local/var/mysql/Zafars-MacBook-Pro-2.local.pid zafarsaleem 86447 0.0 0.0 2435488 920 ?? S 8:07AM 0:00.02 /bin/sh /usr/local/bin/mysqld_safe --max_allowed_packet=32M Please help. How can I resolve this issue.

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• Haskell's type system treats a numerical value as function?

  - by Long

  After playing around with haskell a bit I stumbled over this function: Prelude Data.Maclaurin> :t ((+) . ($) . (+)) ((+) . ($) . (+)) :: (Num a) => a -> (a -> a) -> a -> a (Data.Maclaurin is exported by the package vector-space.) So it takes a Num, a function, another Num and ultimately returns a Num. What magic makes the following work? Prelude Data.Maclaurin> ((+) . ($) . (+)) 1 2 3 6 2 is obviously not a function (a-a) or did I miss out on something?

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• [Cocoa] NSTableView bound to NSArrayController

  - by ndg

  Within Interface Builder I've got an NSTableView with two columns bound to a vanilla NSArrayController. The NSArrayController has its Content Array bound to an NSMutableArray in my application delegate. I've used further bindings to setup the addition and removal of rows via bindings (magic!). The issue I'm running into now is that I'd like to grab the currently selected NSTableView row and use its index to look-up the object stored in my NSArrayControllers associated array. The problem I'm running into is trying to access the NSTableView. Within my application delegate, using the following code will cause my application to crash: NSLog(@"%@", [timersTableView selectedRow]); Similarly, this also causes my application to crash: NSLog(@"%@", [timersController selectionIndex]); Given the simplicity of the code above, I must be doing something fundamentally wrong?

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• exim configuration: 503 AUTH command used when not advertised

  - by jrdioko

  I'm running a piece of software on a Windows server that sends email notifications via a remote SMTP server. It has very few configuration options, and only supports basic SMTP authentication without SSL/TLS. I have exim4 running on a Debian server that will be the SMTP server for this Windows program. It is set up with default configuration, plus allowing AUTH PLAIN and AUTH LOGIN unencrypted connections. I have successfully sent an email over telnet: telnet servername 25 ehlo test 250-AUTH PLAIN LOGIN ... auth plain XXX 235 Authentication succeeded mail from: ... ... However, the program I want to connect to this server fails to connect. To see why, I ran a packet sniffer during the connection, and see the following session: C: HELO hostname S: 250 Hello hostname C: AUTH LOGIN XXX | XXX S: 503 AUTH command used when not advertised | 500 unrecognized command C: QUIT S: 221 closing connection I'm not familiar enough with the SMTP protocol to understand what's going on here. What do I need to change on my exim4 SMTP server to allow for this connection to be made?

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• Debugging asp.net with firefox and visual studio.net - very slow compared to IE

  - by john

  Debugging asp.net websites/web projects in visual studio.net 2005 with Firefox is loads slower than using IE. I've read something somewhere that there is a way of fixing this but i can't for the life of me find it again. Does anyone know what i'm on about and can point me in the right direction please? Cheers John edit sorry rob i haven't explained myself very well(again). I prefer Firefox for debugging (firebug etc) hitting F5 when debugging with IE the browser launches really quickly and clicking around my web application is almost instant and when a breakpont is hit i get to my code straight away with no delays. hitting F5 when debugging with FireFox the browser launches really slowly (ok i have plugins that slow FF loading) but clicking around my web application is really really slow and when a breakpoint is hit it takes ages to break into code. i swear i've read something somewhere that there is a setting in Firefox (about:config maybe?) that when changed to some magic setting sorts all this out.

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• Windows Server 2008 network speed slow, Xen 3.4.3 HVM ISO

  - by Elliot.Bradshaw

  I've setup a VM running Windows Server 2008 on a host node running Xen 3.4.3-5 and the following kernel: 2.6.18-308.1.1.el5xen #1 SMP Wed Mar 7 05:38:01 EST 2012 i686 i686 i386 GNU/Linux The network speed on the VM is very slow--using the online speed tests I can only get it up to 8-9mbps. The line is 100mbps burstable and the host node has no problem achieving those speeds. If it setup a VM running CentOS, it too has no problems achieving those speeds. I've done some pretty exhaustive troubleshooting, but nothing has helped: New VM installations of Win2k8 do have the same network problem. Upgrading to most recent kernel-xen did not help (2.6.18-308.1.1.el5xen). Upgrading from xen 3.4.0 to xen 3.4.3-5 did not help. Disabling Windows firewall, etc did not help. Changing network card device config from auto negotiation to manually be 100mbps full duplex did not help. Changing the network receive buffer packet size did not help (tried all combos from 64k to 8k). At this point I'm pretty much out of ideas--any help would be appreciated!

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• fail2ban log parsing too slow on Raspberry Pi - options? [migrated]

  - by Gordon Morehouse

  I'm running fail2ban on a Raspberry Pi at 950MHz which I cannot overclock further. The Pi is occasionally subject to SYN floods on particular ports. I've set up iptables to throttle the rate of SYNs on the port of interest; when the throttle limits are exceeded, hosts which send SYNs are dropped into the REJECT chain and the particular SYN packet which exceeded the limit is logged. fail2ban then watches for these logged SYNs and, after seeing a few, temporarily bans the host for a short time (this is a transient issue in the app I'm working with). The problem is that the SYN floods can occasionally reach rates which are too fast for fail2ban to keep up with; I'll see 20-40 log messages per second, and eventually fail2ban falls behind and becomes ineffective. To add insult to injury, it continues consuming a LOT of CPU as it tries to catch up. I have verified that DROP chained packets from hosts already banned by fail2ban are not logged, and thus do not add to its load. What are my options here? I have a few ideas, but no clear path forward. Could I make the log-parse regex "easier" so it takes fewer cycles? Would using iptables --log-prefix to put a token near the start of the log message, and/or otherwise simplifying/altering the fail2ban regex help? Here is the current fail2ban config line containing a regex: failregex = kernel:.*?SRC=(?:::f{4,6}:)?(?P<host>[\w\-.^_]+) DST.*?SYN Is there a faster way for fail2ban to watch for the packets exceeding the limits than parsing kern.log? Could fail2ban be run under PyPy instead of CPython with minimal nonstandard wizardry (the OS is Raspbian 7, so, mostly Debian 7)? Is there something better than fail2ban that I could use to watch for the packets which exceed the SYN limits, and after N exceeds in X seconds, temporarily put the offending IP into the iptables DROP bucket, and take it out when the ban timer expires? Again, I'd vastly prefer a solution that uses as much software available in Debian as possible, though I can build Debian packages in a pinch.

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• MagicLibrary.dll 32bit convert for 64bit

  - by Nullstr1ng

  Hi Guys, I recently received an email about a guy who like to make my software compatible with 64Bit Windows 7 OS. I have 1 single problem though .. I have followed a steps regarding on compiling VS Solution/Project for 64bit. But when I start to to compile the solution for 64bit, this "Crownwood.Magic.Forms" (MagicLibrary.dll) doesn't work anymore. This is the compilation error message "Error 6 The type or namespace name 'Crownwood' could not be found (are you missing a using directive or an assembly reference?)" Please don't tell me I did not referenced the MagicLibrary.dll It's a bit of confusing because the MagicLibrary.dll is already in my reference list. I also remove and add it back. There was this CorFlags.exe but am not sure how to convert it to 64bit. "CorFlags MagicLibrary.dll /32BIT- /Force" did not work.. :( Please help. Thanks in advance - Jayson

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• Wireless router blocking some sites while using ethernet is fine

  - by Micke

  I'm using Windows 7 and my router is a wireless Apple Airport Express that is approximately two years old. Suddenly I can't access some sites (for example www.sthlm.friskissvettis.se, or www.vegetarian-shoes.co.uk, some streamed tv-shows on svtplay.se, and a number of other random sites) when connecting to internet with my router. It worked good until recently and I'm fairly sure this problem emerged when my ISP upgraded from 10/10mbit to 100/10mbit speed. Most other sites like facebook and google works fine. When using my network cable to connect to internet everything works fine and I can access these sites. Firmware is current and I've tried reseting the router to factory defaults. Tried different browsers, and I can't ping the "blocked" sites either. Tracert www.sthlm.friskissvettis.se starts with 10.0.0.1 and continues through a number of long addresses until it says timeout. The last working address before timeout was sth-tcy-ipcore01-ge-0-2-0.neq.dgcsystems.net [83.241.252.13], if it matters. Tracert www.vegetarian-shoes.co.uk also eventually gives me a timeout. When the network cable is plugged in, I still get timeout on tracert www.sthlm.friskissvettis.se even though I can access the site in Chrome. Weird. www.vegetarian-shoes.co.uk doesn't give me a tracert timeout when the cable is plugged in, and I can access the site as usual. I've tried changing DNS servers to use opendns servers instead, but to no use. I've tried pinging these two sites with a lower MTU packet size (with this method: http://www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7/), but still can't access them through ping... I don't know what to do anymore.... any suggestions???

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• Fastest way to do mass update

  - by user356004

  Let’s say you have a table with about 5 million records and a nvarchar(max) column populated with large text data. You want to set this column to NULL if SomeOtherColumn = 1 in fastest possible way. The brute force UPDATE does not work very well here because it will create large implicit transaction and take forever. Doing updates in small batches of 50K records at a time works but it’s still taking 47 hrs to complete on beefy 32 core/64GB server. Is there any way to do this update faster? Are there any magic query hints/table options that scarifies something else (like concurrency) in exchange of speed? NOTE: Creating temp table or temp column is not an option because this nvarchar(max) column involves lots of data and so consumes lots of space!

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• What kind of knowledge do you need to invent a new programming language?

  - by systempuntoout

  I just finished to read "Coders at works", a brilliant book by Peter Seibel with 15 interviews to some of the most interesting computer programmers alive today. Well, many of the interviewees have (co)invented\implemented a new programming language. Some examples: Joe Armstrong: Inventor of Erlang L. Peter Deutsch: implementer of Smalltalk-80 Brendan Eich: Inventor of JavaScript Dan Ingalls: Smalltalk implementor and designer Simon Peyton Jones: Coinventor of Haskell Guy Steele: Coinventor of Scheme Is out of any doubt that their minds have something special and unreachable, and i'm not crazy to think i will ever able to create a new language; i'm just interested in this topic. So, imagine a funny\grotesque scenario where your crazy boss one day will come to your desk to say "i want a new programming language with my name on it..take the time you need and do it", which is the right approach to studying this fascinating\intimidating\magic topic? What kind of knowledge do you need to model, design and implement a brand new programming language?

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• Determine the time difference between two linux servers

  - by Paul

  I am troubleshooting a latency network issue on a network. It is probably a nic or cabling issue, but while I was going through the process of figuring it out, I was looking at the timings of a ping packet leaving a network card and arriving at another server. Both linux. So I have tcpdump running on both, and I issue a ping from one to the other, and back again, and looking at the timing differences might have shed light on where the latency is coming from. It is an academic exercise now, as I need to eliminate some more fundamental causes, but I was curious as to how this could be achieved. Given that ntpd is installed and running on two servers, how can I confirm the current time discrepency between the two servers, to whatever level of accuracy is possible - given that we are talking about latency on a local lan, which is ideally a millisecond or so. NTP itself is accurate to a couple of ms under good conditions, and as both servers are in the same environment, they should (presumably) achieve a similar level of accuracy, and so should have a time discrepency between them of a only few ms - but how can I check this?

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• can't Remote desktop to windows XP, blaming the server side

  - by Jin

  After rebooting my work PC (windows XP sp3) this Wednesday (thank to Microsoft Tuesday), I found that I can't remote desktop to my work PC from home (with VPN to company). I have been remote-desktop to work for years and I am really surprised since connectivity is not the problem, so I brought up wireshark to sniff the packets. I can see after TCP handshake, client sent X.224 Connection Request 03 00 00 13 0e e0 00 00 00 00 00 01 00 08 00 03 00 00 00 server sent X.224 Connection Confirm. 03 00 00 0b 06 d0 00 00 12 34 00 According to "MS-RDPBCGR", the official spec on RDP, the server should include Negotiation Response in the "Connection Confirm" message but it didn't. It's empty. I googled a lot but didn't find any clue on why server did that. By the way, I used the same remote desktop client and can connect to other windows XP PC. Here are a couple of pieces of information that may help to give a clue: Since TCP handshake (server port being 3389), I believe the svchost service is actually running. going to control panel -- system window, --- "Remote" tab, the remote desktop is indeeded checked and it states that my username is allowed. according to the packet capture, client didn't even get a chance to tell server what user was trying to logon. Yes, the progress bar showed up a few seconds and then it went back to the "Remote desktop Connection" window again. Searched "windowsupdate.log", didn't find any appearance of the word "remote".

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• Fast Ethernet module for Cisco 2620

  - by Kenny Rasschaert

  I have a Cisco 2620 Router. It comes with one fast ethernet port built in (circled in red), and one old AUI ethernet module is installed (circled in blue). I figure I can put a transceiver on the AUI interface to get a second RJ45 connector. What I'd really like to have is a second fast ethernet connector. The ideal candidate to achieve this would be the NM-1FE-TX module. Cisco claims on their website that this module is not suitable for the Cisco 2620 and Cisco 2620XM. It says so in "Table 2 Physical Limitation of Serial Modules per Chassis". Indeed, this module was designed for the 3600 series of routers. I've seen claims on the internet, however, of people having this module on a 2620XM, and it being fully functional. This claim gains some credibility because of the fact that in Cisco's own Packet Tracer software, you can install this module on the 2620XM router. I'm looking for a definitive answer. Will this module work on a Cisco 2620? Is there perhaps another way to get a second fast ethernet port on this device?

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• How to avoid code repetition initializing final properties?

  - by Hernán Eche

  public class Code{ //many properties //... final String NEWLINE;// ohh a final property! void creation() //this method is for avoid repetition of code { //final initialization can't be put here =( Source= new StringBuffer(); //many other commons new's .. //... } Code() { NEWLINE = System.getProperty("line.separator"); creation(); } Code(String name, int numberr) { NEWLINE = System.getProperty("line.separator"); creation(); name=new Someting(name); number = new Magic(number); } }

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• Overriding routes on Openvpn client, iproute, iptables2

  - by sarvavijJana

  I am looking for some way to route packets based on its destination ports switching regular internet connection and established openvpn tunnel. This is my configuration OpenVPN server ( I have no control over it ) OpenVPN client running ubuntu wlan0 192.168.1.111 - internet connected if Several routes applied on connection to openvpn from server: /sbin/route add -net 207.126.92.3 netmask 255.255.255.255 gw 192.168.1.1 /sbin/route add -net 0.0.0.0 netmask 128.0.0.0 gw 5.5.0.1 /sbin/route add -net 128.0.0.0 netmask 128.0.0.0 gw 5.5.0.1 And I need to route packets regarding it's destination ports for ex: 80,443 into vpn everything else directly to isp connection 192.168.1.1 What i have used during my attempts: iptables -A OUTPUT -t mangle -p tcp -m multiport ! --dports 80,443 -j MARK --set-xmark 0x1/0xffffffff ip rule add fwmark 0x1 table 100 ip route add default via 192.168.1.1 table 100 I was trying to apply this settings using up/down options of openvpn client configuration All my attempts reduced to successful packet delivery and response only via vpn tunnel. Packets routed bypassing vpn i have used some SNAT to gain proper src address iptables -A POSTROUTING -t nat -o $IF -p tcp -m multiport --dports 80,443 -j SNAT --to $IF_IP failed in SYN-ACK like 0 0,1 0,1: "70","192.168.1.111","X.X.X.X","TCP","34314 > 81 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=18664016 TSER=0 WS=7" "71","X.X.X.X","192.168.1.111","TCP","81 > 34314 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1428 TSV=531584430 TSER=18654692 WS=5" "72","X.X.X.X","192.168.1.111","TCP","81 > 34314 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1428 TSV=531584779 TSER=18654692 WS=5" "73","192.168.1.111","X.X.X.X","TCP","34343 > 81 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=18673732 TSER=0 WS=7" I hope someone has already overcome such a situation or probably knows better approach to fulfill requirements. Please kindly give me a good advice or working solution.

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• Lightweight Object->Database in python

  - by pehrs

  I am in need of a lightweight way to store dictionaries of data into a database. What I need is something that: Creates a database table from a simple type description (int, float, datetime etc) Takes a dictionary object and inserts it into the database (including handling datetime objects!) If possible: Can handle basic references, so the dictionary can reference other tables I would prefer something that doesn't do a lot of magic. I just need an easy way to setup and get data into an SQL database. What would you suggest? There seems to be a lot of ORM software around, but I find it hard to evaluate them.

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• How do I set the color for the editButtonItem in the navigation bar of a UITableViewController ?

  - by eemceebee

  Hi I have a UITableViewController where I added a "editButtonItem" in the navigation bar : self.navigationItem.leftBarButtonItem = self.editButtonItem; No magic here, but I try to define the color (background and foreground/textcolor) of this button. I read in the Apple forum somewhere that the button changes the color if I change the navigationbar to the same color, well despite the fact that I do not get this to work either (for testing) I do not want to touch the navigationbr itself, just the button. Since this button is already predefined I am not sure how to handle this. Do I need to overwrite the button with my own definition or can I just simply apply a new style (if so how ?) Thx

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• Unicode characters in URLs

  - by Pekka

  In 2010, would you serve URLs containing UTF-8 characters in a large web portal? Unicode characters are forbidden as per the RFC on URLs (see here). They would have to be percent encoded to be standards compliant. My main point, though, is serving the unencoded characters for the sole purpose of having nice-looking URLs, so percent encoding is out. All major browsers seem to be parsing those URLs okay no matter what the RFC says. My general impression, though, is that it gets very shaky when leaving the domain of web browsers: URLs getting copy+pasted into text files, E-Mails, even Web sites with a different encoding HTTP Client libraries Exotic browsers, RSS readers Is my impression correct that trouble is to be expected here, and thus it's not a practical solution (yet) if you're serving a non-technical audience and it's important that all your links work properly even if quoted and passed on? Is there some magic way of serving nice-looking URLs in HTML http://www.example.com/düsseldorf?neighbourhood=Lörick that can be copy+pasted with the special characters intact, but work correctly when re-used in older clients?

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• Enum.values() vs EnumSet.allOf( ). Which one is more preferable?

  - by Alexander Pogrebnyak

  I looked under the hood for EnumSet.allOf and it looks very efficient, especially for enums with less than 64 values. Basically all sets share the single array of all possible enum values and the only other piece of information is a bitmask which in case of allOf is set in one swoop. On the other hand Enum.values() seems to be a bit of black magic. Moreover it returns an array, not a collection, so in many cases it must be decorated with Arrays.asList( ) to be usable in any place that expects collection. So, should EnumSet.allOf be more preferable to Enum.values? More specifically, which form of for iterator should be used: for ( final MyEnum val: MyEnum.values( ) ); or for ( final MyEnum val: EnumSet.allOf( MyEnum.values ) );

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• Difference between "traceroute" and "traceroute -U"

  - by AndiDog

  The manpage of traceroute says that the "-U" parameter (UDP probing) is the default, but I'm getting different results every time. With "-U": traceroute -U www.univ-paris1.fr traceroute to www.univ-paris1.fr (193.55.96.121), 30 hops max, 60 byte packets [...] 13 rap-vl165-te3-2-jussieu-rtr-021.noc.renater.fr (193.51.181.101) 59.445 ms 56.924 ms 56.651 ms [...] 18 * paris1web.univ-paris1.fr (193.55.96.121) 23.797 ms 23.603 ms but the normal traceroute gives me another result (never reaches the final node) - it's either "!X" or just exits after the maximum of 30 hops: traceroute www.univ-paris1.fr traceroute to www.univ-paris1.fr (193.55.96.121), 30 hops max, 60 byte packets [...] 11 te1-1-paris1-rtr-021.noc.renater.fr (193.51.189.38) 28.147 ms 28.250 ms 28.538 ms [... non-responding nodes ...] 28 site-1.03-jussieu.rap.prd.fr (195.221.126.58) 85.941 ms !X * * Note: I tried this very often and always get the same results. The path in my local network is always the same. So what does the "-U" parameter actually change here? I'm especially interested what the reason for "!X" could be (communication administratively prohibited). EDIT: If that helps, paris-traceroute gives me the following for the last hop: 14 P(1, 6) site-1.03-jussieu.rap.prd.fr (195.221.126.58) 34.938 ms !5 !T2 which means that node discards the packet with TTL=2 and returns an unknown message (not "destination unreachable" or the like).

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