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Windows 7 network performance tuning for LAN

- by Hubert Kario

I want to tune Windows 7 TCP stack for speed in a LAN environment. Bit of background info: I've got a Citrix XenServer set up with Windows 2008R2, Windows 7 and Debian Lenny with Citrix kernel, Windows machines have Tools installed the iperf server process is running on different host, also Debian Lenny. The servers are otherwise idle, tests were repeated few times to confirm results. While testing with iperf 2008R2 can achieve around 600-700Mbps with no tuning what so ever but I can't find any guide or set of parameters that will make Windows 7 achieve anything over 150Mbps with no change in TCP window size using -w parameter to iperf. I tried using netsh autotuining to disabled, experimental, normal and highlyrestricted - no change. Changing congestionprovider doesn't do anything, just as rss and chimney. Setting all the available settings to same values as on Windows 2008R2 host doesn't help. To summarize: Windows 2008R2 default settings: 600-700Mbps Debian, default settings: 600Mbps Windows 7 default settings: 120Mbps Windows 7 default, iperf -w 65536: 400-500Mbps While the missing 400Mbps in performance I blame on crappy Realtek NIC in the XenServer host (I can do ~980Mbps from my laptop to the iperf server) it doesn't explain why Windows 7 can't achieve good performance without manually tuning window size at the application level. So, how to tune Windows 7?

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How to get gigabit network speeds on Windows XP?

- by JB

We've just installed gigabit switches at work, and things on the Linux side are going well. Our linux boxes, which use a Intel Corporation 82566DM-2 Gigabit nic (according to lspci), consistently get over 900 mbits/sec: iperf -c ipserver ------------------------------------------------------------ Client connecting to ipserver, TCP port 5001 TCP window size: 16.0 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.40.9 port 39823 connected with 192.168.1.115 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.08 GBytes 929 Mbits/sec We have a bunch of Windows XP 64-bit machines that use Broadcom NetXtreme 57xx cards. I spent around a day trying to get equivalent speeds on them, but couldn't get above 200 Mbits/sec. I noticed the Windows iperf tests said that the TCP window size was 8 Kb by default (as opposed to 16 Kb on Linux, so I modified my test to reflect that. Still no love. I went to Broadcom's site, downloaded the latest drivers for the card and installed. Still no love. However, finally, I tried a 64 Kb window size with the new drivers, and finally an improvement! $ iperf -c ipserver -w64k ------------------------------------------------------------ Client connecting to ipserver, TCP port 5001 TCP window size: 64.0 KByte ------------------------------------------------------------ [ 3] local 192.168.40.214 port 1848 connected with 192.168.1.115 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 933 MBytes 782 Mbits/sec Much better, but still not really taking advantage of the full capabilities of the network. If the Linux box can reach 950 Mbits/sec consistently, this box should be able to as well. Also, if you're wondering about the medium, this is over the same cable...I'm switching back and forth. Any suggestion or ideas would be really welcome. Thanks!

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Very slow browsing shared folder XP client/host

- by Ickster

I have a pretty straightforward setup where I'm storing media files on an XP pro machine, and sharing the folder to be accessed by other XP pro machines around the house. (Typically, there's only one client accessing the share at a time, although there may be several with the share mounted.) It's been working just fine for years, but I've recently started having some problems. A couple of days ago, the host PC had power disconnected while it was running. It was restarted and everything seemed fine initially, but since then browsing the shared folder from client machines has been extremely slow and actually reading data is all but impossible. The problem exists in every access method I've tried: Windows Explorer, VLC dialogs, command line, etc. My first thought was that the disk was experiencing problems, but there are no problems viewing the files locally on the host machine. My second thought was that there was a network problem on the host machine, so I removed and reinstalled drivers for the NIC with no change. My third thought was that there might've been a problem elsewhere on the network, so I swapped out hardware to no avail. I'm regrouping and trying to come up with a methodical approach to figuring out what might be wrong. I would of course be thrilled if you can suggest specific problems (Microsoft KB articles, etc.) that I might check, but I'm not expecting a silver bullet. If you can help me outline an approach to identify the problem (including recommended tools, e.g., disk checkers, network analyzers, etc.) I'd greatly appreciate it.

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VMWare Guest Info - Wrong IP Returned

- by Jon Bailey

We're running a VDI environment with vSphere 4.0 and Oracle VDI 3.2.2 and are having a bit of a problem with users that connect to an IPSec VPN from within their VM. For some reason, once connected to the VPN, the VMWare API returns GuestInfo.ipAddress as the VPN IP rather than the primary IP of the only NIC on the system. The IP address shown in net[0].ipAddress is the correct address and is what vSphere client is reporting. Is there any way to get VMWare tools to report the net[0].ipAddress as GuestInfo.ipAddress? Below is sample output from the guestinfo.pl script. 172.16.1.2 is the example "bad" VPN address that our VDI software is seeing. VMXFLEX01 guestFamily: windowsGuest VMXFLEX01 guestFullName: Microsoft Windows XP Professional (32-bit) VMXFLEX01 guestId: winXPProGuest VMXFLEX01 guestState: running VMXFLEX01 hostName: VMXFLEX01 VMXFLEX01 ipAddress: 172.16.1.2 VMXFLEX01 toolsStatus: VMware Tools is running and the version is current. VMXFLEX01 toolsVersion: 8194 VMXFLEX01 Screen - Height: 600 VMXFLEX01 Screen - Width: 800 VMXFLEX01 Disk[0]: Capacity 42935926784 VMXFLEX01 Disk[0]: Path : C:\ VMXFLEX01 Disk[0]: freespace : 33272619008 VMXFLEX01 net[0] - connected : 1 VMXFLEX01 net[0] - deviceConfigId : 4000 VMXFLEX01 net[0] - macAddress : 00:50:56:95:1f:c9 VMXFLEX01 net[0] - network : VM Network VMXFLEX01 net[0] - ipAddress : 10.0.0.2

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vDS - vCenter Problem

- by rbmadison

We are implementing a vSphere farm and are using a distrubuted switch. The VC is a VM within the farm connected to the distrubuted switch. We had a SAN issue and all of our VMs were down. When the SAN recovered and we restarted the ESX host containing the VC the VC couldn't connect to the network through the vDS. We had to remove a NIC from the vDS on that host and create a regular vswitch and then connect the VC to that before the VC would connect to the network. Is this typical behavior? If the VC goes down does all vDS networking stop on all the hosts? That seems to be a very bad thing. I thought networking would work even though the VC is down because the hosts have the vDS configuration cached. Is there a better way to configure it to prevent this from happening. We want to keep the VC as a VM for HA and recoverabilty purposes. Can anyone offer suggestions or explanations? I appreciate the help. Thanks, Rick

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Bad network performance on KVM guest

- by Devator

I have a dedicated server connected to a 1000 Mbit port. However, the Debian guest is only getting half to a 1/4 the speeds: On the node itself (Linux node 2.6.32-279.9.1.el6.x86_64 #1 SMP Tue Sep 25 21:43:11 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux): wget http://www.bbned.nl/scripts/speedtest/download/file1000mb.bin -O /dev/null --2012-11-11 23:10:11-- http://www.bbned.nl/scripts/speedtest/download/file1000mb.bin Resolving www.bbned.nl... 62.177.144.181 Connecting to www.bbned.nl|62.177.144.181|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 1048576000 (1000M) [application/octet-stream] Saving to: â/dev/nullâ 100%[====================================>] 1,048,576,000 100M/s in 10s 2012-11-11 23:10:21 (100 MB/s) - â/dev/nullâ On the guest (Debian 6.0.5, x64: Linux debian 2.6.32-5-amd64 #1 SMP Sun Sep 23 10:07:46 UTC 2012 x86_64 GNU/Linux): wget http://www.bbned.nl/scripts/speedtest/download/file1000mb.bin -O /dev/null --2012-11-11 23:10:41-- http://www.bbned.nl/scripts/speedtest/download/file1000mb.bin Resolving www.bbned.nl... 62.177.144.181 Connecting to www.bbned.nl|62.177.144.181|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 1048576000 (1000M) [application/octet-stream] Saving to: â/dev/nullâ 100%[=================================================================================================================================================================================================>] 1,048,576,000 16.5M/s in 42s 2012-11-11 23:11:23 (23.8 MB/s) - â/dev/nullâ I use the virtio NIC. I tried some more NICs: e1000 and the Realtek 8139 but those yield even worse results. Anyone has an idea how to improve these speeds?

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How to switch users without entering password

- by torbengb

I'm a newbie running Ubuntu 9.10. I have two users (wife and me), and each user's screensaver is set to lock so that on wakeup, we get to choose which user's desktop to go to. However, Ubuntu requires a password, so this is pretty tedious. I'd like to switch users without entering any password. I know about this trick that works for the boot login, but it doesn't deal with multiple users. Is it possible to set empty passwords for users in Ubuntu, or skip the password in other ways? (I'm expecting real Linux users to suggest that passwordless users must not get any rights and there be an admin user with a strong password. Yes, you're right. But that's not what this question is about. Thanks.)

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RRAS Public Address Pool on Windows Server 2008

- by Art

I have a Windows 2008 server with two NICs running RRAS and a small public website. It also does NAT for several other PCs on my network and everything works great. I have a block of 5 public static IPs from my ISP, one of which is bound to the public NIC in the Windows 2008 server. I would like to assign one of the remainging 4 public IPs to a machine on my private network. I thought I could do this by going into RRAS, selecting NAT under IPv4 and then adding the public IP address to the address pool and specifying a reservation for the machine I would like to use that address by adding its private ip address. When I do this, the machine I reserved the public IP address for seems to loose all outside network connectivity. I can still ping other PCs on my 192.168.0.* net, but anything outside is no longer reachable. When I remove the reservation, everything seems to work. After setting the reservation and right clicking on the external public interface and selecting 'Show Mappings' I can see outbound requests from my private address with the desired associated private address, however I do not see any inbound requests. What am I doing wrong/missing?

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How to remap IPs visible from local machine to IPs visible from a machine I have SSH access to?

- by gooli

I'm so far out of my depth I don't even know what to google for. There's a server I can connect to via SSH. Via that server I can access other server on its subnet via SSH. What I want to do is be able to access the machines that server has access to directly. Say the server IP is 192.168.7.7 and is the only one in the 192.168.x.x range I have access to. I'd like to configure things in such a way that when I to access say 192.168.7.100 on my machine, the connection will go through an SSH tunnel I open to 192.168.7.7 and out to 192.168.7.100. I would like this to work for any port if at all possible. I know I can set an HTTP proxy and even a SOCKS proxy, but I'm wondering is there is a way to actually remap some of the IP my machine sees to IP only visible from the remote machine. What would this configuration be called? IS this NAT, VPN, IP2IP or something else? How can I set up this on a Windows client box that connects via SSH to a Linux box? Sounds to me like I need to set up some kind of filtering on the network driver or possibly a virtual NIC, but I'm not sure where to go next.

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firehol (firewall) with bridge: how to filter

- by Leon

I have two interfaces: eth0 (public address) and lxcbr0 with 10.0.3.1. I have a LXC guest running with ip 10.0.3.10 This is my firehol config: version 5 trusted_ips=`/usr/local/bin/strip_comments /etc/firehol/trusted_ips` trusted_servers=`/usr/local/bin/strip_comments /etc/firehol/trusted_servers` blacklist full `/usr/local/bin/strip_comments /etc/firehol/blacklist` interface lxcbr0 virtual policy return server "dhcp dns" accept router virtual2internet inface lxcbr0 outface eth0 masquerade route all accept interface any world protection strong #Outgoing these protocols are allowed to everywhere client "smtp pop3 dns ntp mysql icmp" accept #These (incoming) services are available to everyone server "http https smtp ftp imap imaps pop3 pop3s passiveftp" accept #Outgoing, these protocols are only allowed to known servers client "http https webcache ftp ssh pyzor razor" accept dst "${trusted_servers}" On my host I can connect only to "trusted servers" on port 80. In my guest I can connect to port 80 on every host. I assumed that firehol would block that. Is there something I can add/change so that my guest(s) inherit the rules of the eth0 interface?

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how does a computer know which IP address will route information to the internet? [closed]

- by JohnMerlino

Possible Duplicate: How does IPv4 Subnetting Work? For example, I have a computer with a Network Inteface Card (NIC) which is an Ethernet card that is connected by Ethernet cables to a router. There is also another computer with a cable that is connected in another port of the router. This is a Belkin router operating over an Ethernet in the LAN. When I connect to serverfault.com, it maps to an IP address. My computer now has a task of connecting to that IP address. But my computer itself cannot connect to the serverfault IP address. Only the router can. So the task of my computer is to find the IP address associated with the node that will do the routing to the public internet. How does my computer know that a particular IP address in the local network belongs to the router, and is not another computer connected to the network? Is this information configured manually in the operating system itself? Somehow my computer must know that it must send ethernet frames to the router with the expectation that the router will then send the packet to a public IP. How does it know to send it to the router? Is the router's ip address stored in my computer like a key/value pair e.g. "router"="192.168.2.6", so that when I put a public ip address, my computer first knows to connect to 192.168.2.6?

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virtualisation with kvm: export services from guest to the host

- by ascobol

Hello, I would like to export some services from the guest os to the host os, via kvm, and by the same way learn some things about networking. I have tried the following commands: In the host (kubuntu 10.4): $ sudo tunctl -u ascobol Set 'tap0' persistent and owned by uid 2401 $ sudo ifconfig tap0 192.168.2.1 netmask 255.255.255.0 broadcast 192.168.2.255 The ifconfig command returns: $ /sbin/ifconfig tap0 Link encap:Ethernet HWaddr 3e:4e:e3:cc:bc:92 inet addr:192.168.2.1 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::3c4e:e3ff:fecc:bc92/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:17 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 tap0 Then I run the virtual machine (ubuntu server 10.4): $ sudo kvm -hda ubuntuserver104.qcow2 -net nic -net tap,name=tap0,script=no (I'm using sudo because without it fails with the following message:) warning: could not configure /dev/net/tun: no virtual network emulation With sudo the virtual machine boots, I just get this message: pci_add_option_rom: failed to find romfile "pxe-rtl8139.bin" In the virtual machine: $ ifconfig eth0 192.168.2.2 netmask 255.255.255.0 broadcast 192.168.2.255 Now if I run: $ ssh 192.168.2.2 I just get a No route to host What is wrong with this setup ? Thanks !

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Matte or non-widescreen laptop? Do they exist?

- by Alan Harris-Reid

Does anyone know of any matte-screen laptops being sold now (15.6 or 17") in the UK? All I can find is the Dell Vostro 3500/3700 range, but there is a premium of around £200 over the price of their Inspiron range (for the 17" model), and I find it hard justifying the extra cost just to have a matte screen. I do not like glossy screens, but it seems the laptop industry has gone the way of "glossy is better - let's get rid of matte". I have read and heard from other developers that as long as there are no strong light sources to reflect off the screen, one can soon get used to a glossy screen, but I am yet to be convinced. I would also be interested if anyone knows of any non 16:9 screen laptops. I find this ratio too wide and not high-enough for the work I do. 16:10 or lower would be better. Any opinions would be appreciated. Alan

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Anti-spam measures for websites

- by acidzombie24

What are anti-spam measure I should consider before launching my user content website? Some things I have considered: Silent JavaScript based CAPTCHA on the register page (I do not have an implementation) Validate emails by forcing a confirmation link/number Allow X amount of comments per 10 minutes and Y per 2 hours (I am considering excited first time users who want to experience the site) Disallow link until user is trusted (I am not sure how a user will become trusted) Run all comments, messages, etc. through a spam filter. Check to see if messages are duplicate or similar (I may not bother with this. I'd like the system to be strong without this) I also timestamp everything which I then can retrieve as a long on my administrator page. What other measures can I take or consider?

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How do I create a wifi network bridge with qemu on OS X?

- by a paid nerd

I grabbed a small FreeBSD live CD and QEMU, and I'm trying to bridge my Mac OS X 10.8 wifi connection so that the guest OS is available on my LAN. However, the guest OS never gets a DHCP lease. This works perfectly with VirtualBox in their "bridged" network mode, so I know it can be done. I need to get it working with QEMU because VirtualBox doesn't support the architecture that I need for this project. Here's what I've done so far based on hours of googling: Installed TUNTAP for OS X Told OS X to supposedly forward all packets, even ARP: (NOTE: This doesn't appear to work.) $ sudo sysctl -w net.inet.ip.forwarding=1 $ sudo sysctl -w net.link.ether.inet.proxyall=1 $ sudo sysctl -w net.inet.ip.fw.enable=1 Created a bridge: $ sudo ifconfig bridge0 create $ sudo ifconfig bridge0 addm en0 addm tap0 $ sudo ifconfig bridge0 up $ ifconfig bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether ac:de:xx:xx:xx:xx Configuration: priority 0 hellotime 0 fwddelay 0 maxage 0 ipfilter disabled flags 0x2 member: en0 flags=3<LEARNING,DISCOVER> port 4 priority 0 path cost 0 member: tap0 flags=3<LEARNING,DISCOVER> port 8 priority 0 path cost 0 tap0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 ether ca:3d:xx:xx:xx:xx open (pid 88244) Started tcpdump with -I in the hopes that it enables promiscuous mode on the wifi device: $ sudo tcpdump -In -i en0 Run QEMU using the bridged network instructions: $ qemu-system-x86_64 -cdrom mfsbsd-9.2-RELEASE-amd64.iso -m 1024 \ -boot d -net nic -net tap,ifname=tap0,script=no,downscript=no But the guest system never gets a DHCP lease: If I tcpdump -ni tap0, I see lots of traffic from the wireless network. But if I tcpdump -ni en0, I don't see any DHCP traffic from the QEMU guest OS. Any ideas? Update 1: I tried sudo defaults write "/Library/Preferences/SystemConfiguration/com.apple.Boot" "Kernel Flags" "net.inet.ip.scopedroute=0" and rebooting per this mailing list suggestion, but this didn't help. In fact, it made VirtualBox bridged mode stop working.

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Internet doesn't work when enable local Lan

- by rakesh yadav

We have the following network setup: A) Router IP 192.168.51.49 B) Windows Server 2008 R2 with dual NIC: B1) WAN interface (192.168.0.2) ( Used for internet) B2) LAN interface (192.168.1.2) ( used for local connectivity) when i keep both LAN Enabled than my internet doesn't work, but if I disabled my local Lan than internet working fine. so please help me how can resolved this issue or should i need to do routing on my server Please find the below attached route print result C:\Users\Administrator>route print =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.51.49 192.168.51.50 276 0.0.0.0 0.0.0.0 192.168.30.227 192.168.30.228 266 192.168.30.224 255.255.255.240 On-link 192.168.30.228 266 192.168.30.228 255.255.255.255 On-link 192.168.30.228 266 192.168.30.239 255.255.255.255 On-link 192.168.30.228 266 192.168.51.48 255.255.255.240 On-link 192.168.51.50 276 192.168.51.50 255.255.255.255 On-link 192.168.51.50 276 192.168.51.63 255.255.255.255 On-link 192.168.51.50 276 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 202.56.230.5 255.255.255.255 192.168.51.49 192.168.51.50 21 202.56.230.6 255.255.255.255 192.168.51.49 192.168.51.50 21 192.168.26.124 255.255.255.255 192.168.51.49 192.168.51.50 21 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 192.168.51.50 276 224.0.0.0 240.0.0.0 On-link 192.168.30.228 266 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 192.168.51.50 276 255.255.255.255 255.255.255.255 On-link 192.168.30.228 266 =========================================================================== Persistent Routes: Network Address Netmask Gateway Address Metric 0.0.0.0 0.0.0.0 192.168.30.227 Default 0.0.0.0 0.0.0.0 192.168.51.49 Default ===========================================================================

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Troubleshooting loss of network connectivity in Windows 2003 - What else to check?

- by Benny

We are facing a weird problem in our data center. Our Backup server (running EMC Networker) loses network connection every alternate day around 3:00 AM (Backup schedule starts at midnight). After 2 hours of outage, the network connectivity recovers automatically and back to normal. What we observed: It is unlikely to be network issue, since it is directly connected to server farm switch (layer 2 connection without any intermediate hops). Further, the server is connected to two different switches for Load balancing using Broadcomm Teaming. a) If it were a switch related issue it is unlikely that both the network ports go down, since they are connected to different switch. b) A possibility Vlan wide issue is also ruled out since other devices in the same Vlan are fine. c) Switch interface status is always up. But there are lot of packet drops during the outage period - Can be attributed to high interface utilization of the backup server (near 100%) d) Connectivity is restored without any change on network. Next suspect is resource utilization on Windows server. Both CPU and Memory have rarely exceeded 80%, but NIC card utilization is alarmingly high (near 100%) Not really sure how to investigate this?

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Could it be sane to use Windows Server 2012 as desktop

- by nCdy

what about using it on desktop? I've got enough strong PC with intel core i7 and 8GB Ram so what should I think about: why not? Were looking about major differences compared to windows 8, found less. for example new file system - can it affect me? In my usual day I need development instruments alike visual studio, virtualization tools, and some games So far I can't find something that must stop me, everything I need can work (seems like) there. Tell me why I must not do it or if that is sane to do.

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Resolve another domain from current AD domain

- by faulty

We have 2 AD domain setup in our office. First is the primary domain for our office and exchange. The 2nd one is for development use to simulate production environment of our clients. Both domain are hosted on Windows 2008 R2 Enterprise. We, the development team has no access to the office domain other than login and email purpose. DNS is running on PDC of both domain. Both domain does not use public domain name. Now, our machines are joined to the development domain and we use outlook to access our office's exchange. We've added DNS entries for both the domain. From time to time we are having problem resolving our office domain (i.e. during outlook login), which we need to edit our NIC's DNS to have only DNS server from our office and then flush DNS. After that switch back once it's able to resolve. Is there a permanent solution for this scenario like specifying that the office domain be resolve with another DNS server when requested from the development domain? Thanks

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Navigation keys on numeric keypad randomly stop working

- by Tom Hughes

Shortly after a restart, the arrow and navigation (Home, End...) keys on my numeric keypad will randomly stop working, and -- regardless of the state of the NumLock -- return only numbers. I notice this the most in browser applications (like this edit box) but the same effect is true on the command line and in desktop applications like Word. I swapped keyboards and now use a Microsoft keyboard (both are USB keyboards) but the same behavior persists. I also tried a clean boot to clean out startup programs but this made no difference. The separate arrow keys and navigation keys between the QWERTY keys and the numeric keypad work fine, but my strong preference (dating back to DOS and MS Flight Simulator) is to use the navigation keys in the numeric keypad.

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Virtual machines with failover setup

- by kimmmo

We have three servers and our plan is to run a number of virtual machines on them in such manner, that if one of the nodes blow up, we can either quickly or seamlessly get a spare running on another node. In addition to the normal networking, they're interconnected via dual 10Gbit NIC's, so networked raid/mirroring shouldn't be a problem. The guest VM's are mostly going to be running text mode linux, but of course it wouldn't hurt to be able to spin up a non-mission critical windows guest for running Visual Studio or checking IE compatibility of a web app. We've spent some time trying to get some magical cloud setup running using Stackops and Crowbar but it started to look like they were offering way too much and were too complicated for our needs. The next candidate, I think, is Ubuntu 11.04 server + KVM + Ganeti + Drbd, unless you can come up with a suggestion for a better solution that we have missed. Requirements: Installation should be simple or at least understandable without being in the dev team A browser interface for creating and managing VM's is a nice bonus Single node's hardware failure should cause minimal downtime for VM's that were running on that node Adding more nodes should be possible without shutting down the VM's.

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Installing and running a guest OS on KVM-qemu with only serial console access

- by nixnotwin

I am trying to installing a bsd distro with virt-installer. With a Linux distro I used this: virt-install -n debian -r 1024 --vcpus=1 --accelerate -v --disk /var/kvm/installation-disks/debian.img,size=6--nographics --network=bridge:br0,model=ne2k_pci,mac=52:54:00:66:68:09 -l http://ftp.de.debian.org/debian/dists/squeeze/main/installer-amd64/current/images/ -x console=ttyS0,115200 This loads the installer directly from the online mirror. With Fedora I used this mirror: http://www.nic.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/releases/16/Fedora/x86_64/os/ Are there such mirrors for freebsd or openbsd? The reason I want direct installable ftp/http mirrors is because I can access my physical server only via ssh, and it doesn't have a X server or a window manager to give me a VNC GUI. When I tried installing centos 6 with an online mirror I was able to finish the installation via serial console, but after I rebooted it, the serial console never worked for me. I tried everything possible---editing menu.lst, inttab and securtty files. Fedora 16 booted fine from serial console, but got stuck when it loaded anaconda installer. I tried editing freebsd iso installation media by adding serial console option to boot option. And installation was successful. But couldn't boot into it becuase it wasn't giving console acess. I couldn't edit any files as ufs partition cannot be loaded with write access on my Ubuntu server 10.04. Only debian squeeze worked well, it worked for me even without editing a single configuration file. I want to have CLI versions of fedora/centos and freebsd/openbsd. But, looks like there isn't any hope for me to have them, as I have to depend on a serial console to do everything.

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How to debug a kernel created using ubuntu-vm-builder?

- by user265592

Aim: Trying to perform a code walkthrough of what functions are getting called for sending and receiving packets over the network. I am building a kernel and using gdb for debugging/ tracing purposes. I have build a vm using the following command : time sudo ubuntu-vm-builder qemu precise --arch 'amd64' --mem '1024' --rootsize '4096' --swapsize '1024' --kernel-flavour 'generic' --hostname 'ubuntu' --components 'main' --name 'Bob' --user 'ubuntu' --pass 'ubuntu' --bridge 'br0' --libvirt 'qemu:///system' And I can run the VM successfully in qemu using the following command: qemu-system-x86_64 -smp 1 -drive file=tmpGgEOzK.qcow2 "$@" -net nic -net user -serial stdio -redir tcp:2222::22 Now, I want to debug the kernel using gdb. For this I need an executable with debug symbols(vmlinux), which apparently I don't have, as the vm-builder never asked for any such options and simply created a .qcow2 file. Question 1: Am I taking the correct approach to solve the problem and is there an easier way to do it? Question 2: Is there a way to debug this kernel using GDB? P.S: I don't have hardware support for KVM. Please correct me if I am wrong. Thanks.

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Ubuntu Laptop as a wireless hotspot on bridge mode

- by nixnotwin

I have a wired router to which my ubuntu laptop connects via ethernet. The wierless NIC of the laptop acts as a wireless hotspot on master mode. I use hostapd fo this. I have bridged eth0 and wlan0, so my wireless clients that connect to my laptop over wifi get ip from the wired router via dhcp, so the devices get registered at the wired router ( and the laptop is just an access point). I use the following commands to get my laptop+accesspoint working: sudo brctl addbr br0 sudo brctl addif br0 eth0 sudo hostapd /etc/hostapd/hostapd.conf & sudo dhclient -d br0 & sudo ifconfig wlan0 192.168.1.15 netmask 255.255.255.0 up sudo brctl addif br0 wlan0 These commands enable me to access internet on my wireless clients and also on the laptop which is acting as wireless accesspoint. But if I reboot the wired router (without rebooting the laptop that is acting as accesspoint), Internet access on the laptop+accesspoint gets lost, but on wireless clients it works fine. Even I have not been able to figure out a command which will reset the laptop interfaces to default settings, so everytime the router reboots, I have to reboot the laptop too to get into default settings so that I can re-enter the above mentioned commands. My first question is How can I have my bridge+accesspoint up and running even-though the router reboots? And is there a command to set the interfaces to a default state? (ifdown -a doesn't work, after issuing the command the bridge still remained).

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My wifi internet router connection resets when more devices connected

- by joeeoj

The wifi internet router is connected directly to Internet cable. The main Pc is attached to it via LAN cable, while 1 laptop and 3 mobile phones connect to it via wifi. Whenever 2 or more devices connect via wifi, the internet connection breaks after one minute and internet connection resets. I tracked this behaviour for weeks, and came to conclusion: It seems like some 'device 1' got IP then it went to suspend mode. Then 'device 2' connected to router and got the same IP. Then the 'device 1' woke up from suspend mode and tried to use his old IP. The router sees that 2 same IP addresses exists and automatically reset internet connection. Is this possible? Have I tracked the problem correctly and how to solve it? The router is set to lease 100 IP addresses to devices who try to connect. The password is strong and no hacker's device is being connected to my wifi network. Tried changing password and AP's name.

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