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  • Get Autonumber from newly inserted record in Access 2007 using Enterprise Library 4.1

    - by silverCORE
    It's been ages since I last used Access as a back end but I'm being forced to. I'm using Enterprise Library 4.1, the Data Access Application Block.. with .NET 3.5 and I wanted to know the best way (code sample if possible) to write an insert query that will automatically give me the newly inserted auto-number back..or if it's not possible to do it in one step, how do you recommend doing it? thanks for your help.

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  • Create Directory for records in MS Access 2007

    - by glinch
    Hi there, Is it possible to create a directory folder for individual records in Access 2007. For example tblUser ID firstName surName When adding a record, would create a folder C:\userdatabase\Surname,firstName,ID Could see this being useful in situations for example where a large amount of images/files would need to be associated with a record. Access would create and link to a directory for each record. Thanks in advance for any advice Noel

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  • Ops Center 12c - Provisioning Solaris Using a Card-Based NIC

    - by scottdickson
    It's been a long time since last I added something here, but having some conversations this last week, I got inspired to update things. I've been spending a lot of time with Ops Center for managing and installing systems these days.  So, I suspect a number of my upcoming posts will be in that area. Today, I want to look at how to provision Solaris using Ops Center when your network is not connected to one of the built-in NICs.  We'll talk about how this can work for both Solaris 10 and Solaris 11, since they are pretty similar.  In both cases, WANboot is a key piece of the story. Here's what I want to do:  I have a Sun Fire T2000 server with a Quad-GbE nxge card installed.  The only network is connected to port 2 on that card rather than the built-in network interfaces.  I want to install Solaris on it across the network, either Solaris 10 or Solaris 11.  I have met with a lot of customers lately who have a similar architecture.  Usually, they have T4-4 servers with the network connected via 10GbE connections. Add to this mix the fact that I use Ops Center to manage the systems in my lab, so I really would like to add this to Ops Center.  If possible, I would like this to be completely hands free.  I can't quite do that yet. Close, but not quite. WANBoot or Old-Style NetBoot? When a system is installed from the network, it needs some help getting the process rolling.  It has to figure out what its network configuration (IP address, gateway, etc.) ought to be.  It needs to figure out what server is going to help it boot and install, and it needs the instructions for the installation.  There are two different ways to bootstrap an installation of Solaris on SPARC across the network.   The old way uses a broadcast of RARP or more recently DHCP to obtain the IP configuration and the rest of the information needed.  The second is to explicitly configure this information in the OBP and use WANBoot for installation WANBoot has a number of benefits over broadcast-based installation: it is not restricted to a single subnet; it does not require special DHCP configuration or DHCP helpers; it uses standard HTTP and HTTPS protocols which traverse firewalls much more easily than NFS-based package installation.  But, WANBoot is not available on really old hardware and WANBoot requires the use o Flash Archives in Solaris 10.  Still, for many people, this is a great approach. As it turns out, WANBoot is necessary if you plan to install using a NIC on a card rather than a built-in NIC. Identifying Which Network Interface to Use One of the trickiest aspects to this process, and the one that actually requires manual intervention to set up, is identifying how the OBP and Solaris refer to the NIC that we want to use to boot.  The OBP already has device aliases configured for the built-in NICs called net, net0, net1, net2, net3.  The device alias net typically points to net0 so that when you issue the command  "boot net -v install", it uses net0 for the boot.  Our task is to figure out the network instance for the NIC we want to use.  We will need to get to the OBP console of the system we want to install in order to figure out what the network should be called.  I will presume you know how to get to the ok prompt.  Once there, we have to see what networks the OBP sees and identify which one is associated with our NIC using the OBP command show-nets. SunOS Release 5.11 Version 11.0 64-bit Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. {4} ok banner Sun Fire T200, No Keyboard Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548. Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c. {4} ok show-nets a) /pci@7c0/pci@0/pci@2/network@0,1 b) /pci@7c0/pci@0/pci@2/network@0 c) /pci@780/pci@0/pci@8/network@0,3 d) /pci@780/pci@0/pci@8/network@0,2 e) /pci@780/pci@0/pci@8/network@0,1 f) /pci@780/pci@0/pci@8/network@0 g) /pci@780/pci@0/pci@1/network@0,1 h) /pci@780/pci@0/pci@1/network@0 q) NO SELECTION Enter Selection, q to quit: d /pci@780/pci@0/pci@8/network@0,2 has been selected. Type ^Y ( Control-Y ) to insert it in the command line. e.g. ok nvalias mydev ^Y for creating devalias mydev for /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias ... net3 /pci@7c0/pci@0/pci@2/network@0,1 net2 /pci@7c0/pci@0/pci@2/network@0 net1 /pci@780/pci@0/pci@1/network@0,1 net0 /pci@780/pci@0/pci@1/network@0 net /pci@780/pci@0/pci@1/network@0 ... name aliases By looking at the devalias and the show-nets output, we can see that our Quad-GbE card must be the device nodes starting with  /pci@780/pci@0/pci@8/network@0.  The cable for our network is plugged into the 3rd slot, so the device address for our network must be /pci@780/pci@0/pci@8/network@0,2. With that, we can create a device alias for our network interface.  Naming the device alias may take a little bit of trial and error, especially in Solaris 11 where the device alias seems to matter more with the new virtualized network stack. So far in my testing, since this is the "next" network interface to be used, I have found success in naming it net4, even though it's a NIC in the middle of a card that might, by rights, be called net6 (assuming the 0th interface on the card is the next interface identified by Solaris and this is the 3rd interface on the card).  So, we will call it net4.  We need to assign a device alias to it: {4} ok nvalias net4 /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias net4 /pci@780/pci@0/pci@8/network@0,2 ... We also may need to have the MAC for this particular interface, so let's get it, too.  To do this, we go to the device and interrogate its properties. {4} ok cd /pci@780/pci@0/pci@8/network@0,2 {4} ok .properties assigned-addresses 82060210 00000000 03000000 00000000 01000000 82060218 00000000 00320000 00000000 00008000 82060220 00000000 00328000 00000000 00008000 82060230 00000000 00600000 00000000 00100000 local-mac-address 00 21 28 20 42 92 phy-type mif ... From this, we can see that the MAC for this interface is  00:21:28:20:42:92.  We will need this later. This is all we need to do at the OBP.  Now, we can configure Ops Center to use this interface. Network Boot in Solaris 10 Solaris 10 turns out to be a little simpler than Solaris 11 for this sort of a network boot.  Since WANBoot in Solaris 10 fetches a specified In order to install the system using Ops Center, it is necessary to create a OS Provisioning profile and its corresponding plan.  I am going to presume that you already know how to do this within Ops Center 12c and I will just cover the differences between a regular profile and a profile that can use an alternate interface. Create a OS Provisioning profile for Solaris 10 as usual.  However, when you specify the network resources for the primary network, click on the name of the NIC, probably GB_0, and rename it to GB_N/netN, where N is the instance number you used previously in creating the device alias.  This is where the trial and error may come into play.  You may need to try a few instance numbers before you, the OBP, and Solaris all agree on the instance number.  Mark this as the boot network. For Solaris 10, you ought to be able to then apply the OS Provisioning profile to the server and it should install using that interface.  And if you put your cards in the same slots and plug the networks into the same NICs, this profile is reusable across multiple servers. Why This Works If you watch the console as Solaris boots during the OSP process, Ops Center is going to look for the device alias netN.  Since WANBoot requires a device alias called just net, Ops Center uses the value of your netN device alias and assigns that device to the net alias.  That means that boot net will automatically use this device.  Very cool!  Here's a trace from the console as Ops Center provisions a server: Sun Sun Fire T200, No KeyboardCopyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548.Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c.auto-boot? =            false{0} ok  {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2 See what happened?  Ops Center looked for the network device alias called net4 that we specified in the profile, took the value from it, and made it the net device alias for the boot.  Pretty cool! WANBoot and Solaris 11 Solaris 11 requires an additional step since the Automated Installer in Solaris 11 uses the MAC address of the network to figure out which manifest to use for system installation.  In order to make sure this is available, we have to take an extra step to associate the MAC of the NIC on the card with the host.  So, in addition to creating the device alias like we did above, we also have to declare to Ops Center that the host has this new MAC. Declaring the NIC Start out by discovering the hardware as usual.  Once you have discovered it, take a look under the Connectivity tab to see what networks it has discovered.  In the case of this system, it shows the 4 built-in networks, but not the networks on the additional cards.  These are not directly visible to the system controller.  In order to add the additional network interface to the hardware asset, it is necessary to Declare it.  We will declare that we have a server with this additional NIC, but we will also  specify the existing GB_0 network so that Ops Center can associate the right resources together.  The GB_0 acts as sort of a key to tie our new declaration to the old system already discovered.  Go to the Assets tab, select All Assets, and then in the Actions tab, select Add Asset.  Rather than going through a discovery this time, we will manually declare a new asset. When we declare it, we will give the hostname, IP address, system model that match those that have already been discovered.  Then, we will declare both GB_0 with its existing MAC and the new GB_4 with its MAC.  Remember that we collected the MAC for GB_4 when we created its device alias. After you declare the asset, you will see the new NIC in the connectivity tab for the asset.  You will notice that only the NICs you listed when you declared it are seen now.  If you want Ops Center to see all of the existing NICs as well as the additional one, declare them as well.  Add the other GB_1, GB_2, GB_3 links and their MACs just as you did GB_0 and GB_4.  Installing the OS  Once you have declared the asset, you can create an OS Provisioning profile for Solaris 11 in the same way that you did for Solaris 10.  The only difference from any other provisioning profile you might have created already is the network to use for installation.  Again, use GB_N/netN where N is the interface number you used for your device alias and in your declaration.  And away you go.  When the system boots from the network, the automated installer (AI) is able to see which system manifest to use, based on the new MAC that was associated, and the system gets installed. {0} ok {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2...SunOS Release 5.11 Version 11.0 64-bitCopyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved.Remounting root read/writeProbing for device nodes ...Preparing network image for useDownloading solaris.zlib--2012-02-17 15:10:17--  http://10.140.204.22:5555/var/js/AI/sparc//solaris.zlibConnecting to 10.140.204.22:5555... connected.HTTP request sent, awaiting response... 200 OKLength: 126752256 (121M) [text/plain]Saving to: `/tmp/solaris.zlib'100%[======================================>] 126,752,256 28.6M/s   in 4.4s    2012-02-17 15:10:21 (27.3 MB/s) - `/tmp/solaris.zlib' saved [126752256/126752256] Conclusion So, why go to all of this trouble?  More and more, I find that customers are wiring their data center to only use higher speed networks - 10GbE only to the hosts.  Some customers are moving aggressively toward consolidated networks combining storage and network on CNA NICs.  All of this means that network-based provisioning cannot rely exclusively on the built-in network interfaces.  So, it's important to be able to provision a system using other than the built-in networks.  Turns out, that this is pretty straight-forward for both Solaris 10 and Solaris 11 and fits into the Ops Center deployment process quite nicely. Hopefully, you will be able to use this as you build out your own private cloud solutions with Ops Center.

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  • Auto blocking attacking IP address

    - by dong
    This is to share my PowerShell code online. I original asked this question on MSDN forum (or TechNet?) here: http://social.technet.microsoft.com/Forums/en-US/winserversecurity/thread/f950686e-e3f8-4cf2-b8ec-2685c1ed7a77 In short, this is trying to find attacking IP address then add it into Firewall block rule. So I suppose: 1, You are running a Windows Server 2008 facing the Internet. 2, You need to have some port open for service, e.g. TCP 21 for FTP; TCP 3389 for Remote Desktop. You can see in my code I’m only dealing with these two since that’s what I opened. You can add further port number if you like, but the way to process might be different with these two. 3, I strongly suggest you use STRONG password and follow all security best practices, this ps1 code is NOT for adding security to your server, but reduce the nuisance from brute force attack, and make sys admin’s life easier: i.e. your FTP log won’t hold megabytes of nonsense, your Windows system log will not roll back and only can tell you what happened last month. 4, You are comfortable with setting up Windows Firewall rules, in my code, my rule has a name of “MY BLACKLIST”, you need to setup a similar one, and set it to BLOCK everything. 5, My rule is dangerous because it has the risk to block myself out as well. I do have a backup plan i.e. the DELL DRAC5 so that if that happens, I still can remote console to my server and reset the firewall. 6, By no means the code is perfect, the coding style, the use of PowerShell skills, the hard coded part, all can be improved, it’s just that it’s good enough for me already. It has been running on my server for more than 7 MONTHS. 7, Current code still has problem, I didn’t solve it yet, further on this point after the code. :)    #Dong Xie, March 2012  #my simple code to monitor attack and deal with it  #Windows Server 2008 Logon Type  #8: NetworkCleartext, i.e. FTP  #10: RemoteInteractive, i.e. RDP    $tick = 0;  "Start to run at: " + (get-date);    $regex1 = [regex] "192\.168\.100\.(?:101|102):3389\s+(\d+\.\d+\.\d+\.\d+)";  $regex2 = [regex] "Source Network Address:\t(\d+\.\d+\.\d+\.\d+)";    while($True) {   $blacklist = @();     "Running... (tick:" + $tick + ")"; $tick+=1;    #Port 3389  $a = @()  netstat -no | Select-String ":3389" | ? { $m = $regex1.Match($_); `    $ip = $m.Groups[1].Value; if ($m.Success -and $ip -ne "10.0.0.1") {$a = $a + $ip;} }  if ($a.count -gt 0) {    $ips = get-eventlog Security -Newest 1000 | Where-Object {$_.EventID -eq 4625 -and $_.Message -match "Logon Type:\s+10"} | foreach { `      $m = $regex2.Match($_.Message); $ip = $m.Groups[1].Value; $ip; } | Sort-Object | Tee-Object -Variable list | Get-Unique    foreach ($ip in $a) { if ($ips -contains $ip) {      if (-not ($blacklist -contains $ip)) {        $attack_count = ($list | Select-String $ip -SimpleMatch | Measure-Object).count;        "Found attacking IP on 3389: " + $ip + ", with count: " + $attack_count;        if ($attack_count -ge 20) {$blacklist = $blacklist + $ip;}      }      }    }  }      #FTP  $now = (Get-Date).AddMinutes(-5); #check only last 5 mins.     #Get-EventLog has built-in switch for EventID, Message, Time, etc. but using any of these it will be VERY slow.  $count = (Get-EventLog Security -Newest 1000 | Where-Object {$_.EventID -eq 4625 -and $_.Message -match "Logon Type:\s+8" -and `              $_.TimeGenerated.CompareTo($now) -gt 0} | Measure-Object).count;  if ($count -gt 50) #threshold  {     $ips = @();     $ips1 = dir "C:\inetpub\logs\LogFiles\FPTSVC2" | Sort-Object -Property LastWriteTime -Descending `       | select -First 1 | gc | select -Last 200 | where {$_ -match "An\+error\+occured\+during\+the\+authentication\+process."} `        | Select-String -Pattern "(\d+\.\d+\.\d+\.\d+)" | select -ExpandProperty Matches | select -ExpandProperty value | Group-Object `        | where {$_.Count -ge 10} | select -ExpandProperty Name;       $ips2 = dir "C:\inetpub\logs\LogFiles\FTPSVC3" | Sort-Object -Property LastWriteTime -Descending `       | select -First 1 | gc | select -Last 200 | where {$_ -match "An\+error\+occured\+during\+the\+authentication\+process."} `        | Select-String -Pattern "(\d+\.\d+\.\d+\.\d+)" | select -ExpandProperty Matches | select -ExpandProperty value | Group-Object `        | where {$_.Count -ge 10} | select -ExpandProperty Name;     $ips += $ips1; $ips += $ips2; $ips = $ips | where {$_ -ne "10.0.0.1"} | Sort-Object | Get-Unique;         foreach ($ip in $ips) {       if (-not ($blacklist -contains $ip)) {        "Found attacking IP on FTP: " + $ip;        $blacklist = $blacklist + $ip;       }     }  }        #Firewall change <# $current = (netsh advfirewall firewall show rule name="MY BLACKLIST" | where {$_ -match "RemoteIP"}).replace("RemoteIP:", "").replace(" ","").replace("/255.255.255.255",""); #inside $current there is no \r or \n need remove. foreach ($ip in $blacklist) { if (-not ($current -match $ip) -and -not ($ip -like "10.0.0.*")) {"Adding this IP into firewall blocklist: " + $ip; $c= 'netsh advfirewall firewall set rule name="MY BLACKLIST" new RemoteIP="{0},{1}"' -f $ip, $current; Invoke-Expression $c; } } #>    foreach ($ip in $blacklist) {    $fw=New-object –comObject HNetCfg.FwPolicy2; # http://blogs.technet.com/b/jamesone/archive/2009/02/18/how-to-manage-the-windows-firewall-settings-with-powershell.aspx    $myrule = $fw.Rules | where {$_.Name -eq "MY BLACKLIST"} | select -First 1; # Potential bug here?    if (-not ($myrule.RemoteAddresses -match $ip) -and -not ($ip -like "10.0.0.*"))      {"Adding this IP into firewall blocklist: " + $ip;         $myrule.RemoteAddresses+=(","+$ip);      }  }    Wait-Event -Timeout 30 #pause 30 secs    } # end of top while loop.   Further points: 1, I suppose the server is listening on port 3389 on server IP: 192.168.100.101 and 192.168.100.102, you need to replace that with your real IP. 2, I suppose you are Remote Desktop to this server from a workstation with IP: 10.0.0.1. Please replace as well. 3, The threshold for 3389 attack is 20, you don’t want to block yourself just because you typed your password wrong 3 times, you can change this threshold by your own reasoning. 4, FTP is checking the log for attack only to the last 5 mins, you can change that as well. 5, I suppose the server is serving FTP on both IP address and their LOG path are C:\inetpub\logs\LogFiles\FPTSVC2 and C:\inetpub\logs\LogFiles\FPTSVC3. Change accordingly. 6, FTP checking code is only asking for the last 200 lines of log, and the threshold is 10, change as you wish. 7, the code runs in a loop, you can set the loop time at the last line. To run this code, copy and paste to your editor, finish all the editing, get it to your server, and open an CMD window, then type powershell.exe –file your_powershell_file_name.ps1, it will start running, you can Ctrl-C to break it. This is what you see when it’s running: This is when it detected attack and adding the firewall rule: Regarding the design of the code: 1, There are many ways you can detect the attack, but to add an IP into a block rule is no small thing, you need to think hard before doing it, reason for that may include: You don’t want block yourself; and not blocking your customer/user, i.e. the good guy. 2, Thus for each service/port, I double check. For 3389, first it needs to show in netstat.exe, then the Event log; for FTP, first check the Event log, then the FTP log files. 3, At three places I need to make sure I’m not adding myself into the block rule. –ne with single IP, –like with subnet.   Now the final bit: 1, The code will stop working after a while (depends on how busy you are attacked, could be weeks, months, or days?!) It will throw Red error message in CMD, don’t Panic, it does no harm, but it also no longer blocking new attack. THE REASON is not confirmed with MS people: the COM object to manage firewall, you can only give it a list of IP addresses to the length of around 32KB I think, once it reaches the limit, you get the error message. 2, This is in fact my second solution to use the COM object, the first solution is still in the comment block for your reference, which is using netsh, that fails because being run from CMD, you can only throw it a list of IP to 8KB. 3, I haven’t worked the workaround yet, some ideas include: wrap that RemoteAddresses setting line with error checking and once it reaches the limit, use the newly detected IP to be the list, not appending to it. This basically reset your block rule to ground zero and lose the previous bad IPs. This does no harm as it sounds, because given a certain period has passed, any these bad IPs still not repent and continue the attack to you, it only got 30 seconds or 20 guesses of your password before you block it again. And there is the benefit that the bad IP may turn back to the good hands again, and you are not blocking a potential customer or your CEO’s home pc because once upon a time, it’s a zombie. Thus the ZEN of blocking: never block any IP for too long. 4, But if you insist to block the ugly forever, my other ideas include: You call MS support, ask them how can we set an arbitrary length of IP addresses in a rule; at least from my experiences at the Forum, they don’t know and they don’t care, because they think the dynamic blocking should be done by some expensive hardware. Or, from programming perspective, you can create a new rule once the old is full, then you’ll have MY BLACKLIST1, MY  BLACKLIST2, MY BLACKLIST3, … etc. Once in a while you can compile them together and start a business to sell your blacklist on the market! Enjoy the code! p.s. (PowerShell is REALLY REALLY GREAT!)

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  • Windows 7, network connection with no default gateway: any way to change the "Unknown network" statu

    - by e-t172
    Hi, I have a computer running Windows 7 Pro RTM. This computer has two network connections: A Wi-fi connection to the Internet (through a home router) which works just fine. An OpenVPN virtual network connection. More precisely, this is a virtual Ethernet connection which behaves exactly like a physical Ethernet wired connection. My problem is that the "Network and sharing center" shows "Unknown network" for the OpenVPN connection. After some research I found that logical networks (outside a domain) are identified by the MAC address of the default gateway of the connection. Problem is, the OpenVPN connection has no default gateway: it is a private network, so I don't need one... Consequently, the "Unknown network" is always considered public, so the firewall is always in "public mode", which I don't want. Plus, I can't rename "Unknown connection" or anything (which makes sense), so it is kinda ugly. My goal is to define a proper logical network for the OpenVPN connection with the private profile. I know of some workarounds (disable the firewall, modify security policy to make all unknown networks "private") but they're still workarounds. I just want my clients to connect to the VPN without having to disable their firewall settings, without changing global configuration with potential side-effects (the "security policy" solution) and without having to look at an ugly "Unknown connection" in the Network and sharing center. Is there any way I can do this? I tried to check what was going on in the registry (HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList is interesting), but I still didn't find a way to "force" the OpenVPN connection to be assigned to a logical network. Any help would be very appreciated. A related question showed up at Superuser: http://superuser.com/questions/37355/windows-7-cant-identify-network/37422

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  • When importing an Access table into Excel, a look-up column is showing all values as numbers

    - by user3651997
    I have a basic Access to Excel question that has me frustrated. I have two Access 2010 data tables. One is a list of managers. The primary key is a manager ID (which is an autonumber because managers can have the same name), and each row also has manager name, manager email, etc. The second data table is a list of departments. The primary key for each row is a unique department code, and the foreign key is a manager ID (autonumber). I used the Look-up Wizard to create this connection. However, Access does not show the manager ID in the foreign key location. It shows Manager Name like I requested when I used the Look-up Wizard. Now I am trying to import the second table (departments) into Excel 2010. I clicked import from Access, chose the Department table, and everything popped into Excel. BUT, the Manager Name column is showing Manager ID instead. So I have a list of numbers instead of names. How can I make Excel show what I see in Access? Thanks!

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  • How can I share a Windows 7 library with anonymous access without using a Homegroup?

    - by Triynko
    The "homegroup" feature is useless, because it requires a password, and therefore doesn't support anonymous, no-hassle access to shares from devices such as my Sony Bravia TV and non-Windows7 machines. So I turned off homegroup and reverted to the standard shared folders protocol. I'd like to share my Music "Library", so I can play files from my TV through the Surround Sound System, but there seems to be no option to share a library folder other than through a homegroup. I don't want to have to individually share the folders that belong to the library, because that would defeat the purposes of the library, which is to manage which folders are included in the library while also providing an easily accessible view of them all at once. Does anyone know how to share a Windows 7 library without that useless homegroup feature?

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  • How can I share a Windows 7 library with anonymous access without using a Homegroup?

    - by Triynko
    The "homegroup" feature is useless, because it requires a password, and therefore doesn't support anonymous, no-hassle access to shares from devices such as my Sony Bravia TV and non-Windows7 machines. So I turned off homegroup and reverted to the standard shared folders protocol. I'd like to share my Music "Library", so I can play files from my TV through the Surround Sound System, but there seems to be no option to share a library folder other than through a homegroup. I don't want to have to individually share the folders that belong to the library, because that would defeat the purposes of the library, which is to manage which folders are included in the library while also providing an easily accessible view of them all at once. Does anyone know how to share a Windows 7 library without that useless homegroup feature?

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  • management network to a network port for additional ones munin and monit

    - by paolo
    management network to a network port for additional ones munin and monit I want to build a separate Netzwek for server management. I have several network cards a linux / debian / ubuntu with computer. Set both network cards sin in the /etc/network/interfaces. # The primary network interface #allow-hotplug eth0 #iface eth0 inet dhcp auto eth0 iface eth0 inet static address 10.0.0.240 netmast 255.255.255.0 network 10.0.0.0 brodacast 10.0.0.255 gateway 10.0.0.254 auto eth1 iface eth1 inet static address 10.0.10.240 netmast 255.255.255.0 network 10.0.10.0 brodacast 10.0.10.255 post-up ip route add 10.0.0.0/24 dev eth0 src 10.0.0.240 table eth0-WAN post-up ip route add default via 10.0.0.254 table eth0-WAN post-up ip route add 10.0.10.0/24 dev eth1 src 10.0.10.240 table eth1-LAN post-up ip route add default via 10.0.10.200 table eth1-LAN post-up ip rule add from 10.0.0.240 table eth0-WAN post-up ip rule add from 10.0.10.240 table eth1-LAN still i adjusted / etc/iproute2/rt_tables and following routes set up in the /etc/network/interfaces I want to have both applications and the network interface separately as munin and monit only on eth1 and not have to eth0. it goes to the reboot but sometimes not always. # Traceroute-i eth1 10.0.10.200 not go what am I doing wrong?

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  • The Network folder specified is currently mapped using a different user name and password

    - by Frank Thornton
    I have a NAS device, it has 3 shares. On one computer I have access to all 3 of the shares. On another computer I keep getting this error when try and add a 2nd one. The Network folder specified is currently mapped using a different user name and password [...] That is the message I keep getting. What causes that? EDIT: Every share has it's own username and password. EDIT: NET USE on the one running 3 from the same NAS device New connections will be remembered. Status Local Remote Network ------------------------------------------------------------------------------- OK T: \\192.168.2.5\SHARE1 Microsoft Windows Network OK X: \\Nas-1dsho-abc\SHARE2 Microsoft Windows Network Disconnected Y: \\192.168.2.9\backups Microsoft Windows Network OK Z: \\Nas-1dsho-abc\cbackups Microsoft Windows Network The command completed successfully. NET USE on the other: New connections will be remembered. Status Local Remote Network ------------------------------------------------------------------------------- OK Y: \\192.168.2.5\SHARE1 Microsoft Windows Network Unavailable Z: \\192.168.2.5\SHARE2 Microsoft Windows Network The command completed successfully.

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  • Adding new records in Access without wrecking the form

    - by Matt Parker
    I'm working on a simple Access 2003 application to keep track of things that need to be done for clients for some colleagues. Each colleague has a set of clients, and each client has a set of actions that need to be taken by a certain date. I've set up a form that consists of a combobox for client ID (indexed), a drop-down for the person who is handling that client's case, and a button for adding new clients (a standard Access-created Add Record button). The actions are listed in a subform below these three elements. The problem I've run into is that the first person I tested this on clicked the button to add a new record, then didn't fill it out and tried to select another client from the drop-down list. Access interprets this as an attempt to set the selected Client ID as the ID for the new record and rightfully throws an error for duplicate primary keys. I can think of a couple of ways around this problem, but I'd much rather hear your elegant solutions than kludge together some junk in a language I don't know. Let me know if you have any questions. Thank you.

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  • Cannot connect to Onda GSM phone using network-manager

    - by marcobra
    On Oneiric unstable fully updated/upgraded using network-manager broadband connection with: ID 19d2:1015 ONDA Communication S.p.A. I want some hints to make a Onda GSM usbkey 19d2:1015 work? route show me Destination Gateway Genmask Flags Metric Ref Use Iface default * 0.0.0.0 U 0 0 0 usb0 link-local * 255.255.0.0 U 1000 0 0 usb0 It connects and the usb0 device get ip-address from the provider but I cannot get webpages (also typing a known ip in firefox) It seem to be something about routing default gw, there is no active firewall on this pc btw, all works using sakis3g or wvdial or gnome-ppp

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  • Network Manager Applet menu freezes and does not respond

    - by pst007x
    Since the latest update in Ubuntu 10.10, the nm-applet has started doing some strange things. I boot up the PC, all is fine, internet works, etc... but after a period of time, approx and hour, the nm-applet menu in the Gnome panel fails to respond. when I click on the icon, the menu appears, all looks well, but when I select any option, eg DISCONNECT, nothing happens. Even the VPN sub menu disappears (no triangle to select the menu.) However I do not lose the network connection... If I Run this script: killall nm-applet /etc/init.d/NetworkManager restart nm-applet all returns as normal, for a while... weird? i tried uninstall/reinstall... I even reinstalled Ubuntu, but once the latest updates are applied this issues arises... Any help?

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  • Ubuntu 12.04 Wireless won't connect with gnome network manager or wicd

    - by iceblueirish
    I have an HP Pavilion Slimline s3100n and I cannot for the life of me get the wifi to connect and stay connected in any circumstances with network manager or wicd... I'm pulling my freaking hair out with this, and I can't get a dang thing down AT ALL... switching to wicd didn't work, putting my password in the connections editor didn't work... nothing at all is working... everything that everyone else is saying to me is chinese and I really just want my pc to work... please help... I will provide any information needed to help me with this. just instruct me on how to find that information. Don't pass this question by without helping me please... I'm so frustrated...

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  • Thomson TG782T ADSL2+ modem loses network connection

    - by squashbuff
    I am using an ubuntu 10.04 server (running on a Lenovo Thinkpad notebook) as my webserver. It is performing well in terms of handling the traffic etc. However my internet connection is ADSL2+ (using Thomson TG782T modem-router) and if the modem is reset, then my server loses network connection. The networkmanager icon shows a red exclamation mark showing that is has no connection. But as soon as I click on it and tell it to connect to eth0, the connection is back on. It must be something that networkmanager is failing to do and because of this, the reliability of my webserver is suffering. Any advice on how this can be fixed?

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  • OpenVPN is installed but it is not an avaliable option in the network manager

    - by Relik
    I have installed and used openVPN once before in a previous install of Ubuntu 12.04. I have since reformatted, and now after reinstalling openVPN it will not show up in the network manager. I am trying to setup my VPN connection and the only option I have to choose from is PPTP. EDIT: I have Gnome Shell and KDE installed as well, Gnome being my primary. I cannot find OpenVPN in either Gnome or Unity, however I can add it without an issue in KDE. Not really an acceptable workaround, but it works for now. I would still like to be able to do it in GTK based desktops as well.

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  • Network manager indicator missing

    - by Jarmo
    I recently upgraded from 11.10 to 12.04. My first attempt failed, and I received an error stating that not all of the required packages were downloaded. Before (successfully) attempting again, I noticed that there was no longer a networking indicator in the upper panel. The indicator did not reappear with the installation of 12.04. To be clear, my wireless connection has experienced no problems, despite the missing indicator. Here are the solutions that I have found which did not work for me: Editing /etc/NetworkManager/NetworkManager.conf and replacing [ifupdown] managed=false with =true. Reinstalling network-manager (via apt-get install --reinstall). I am currently running 12.04 on an Asus Eee PC 1005 HA, and I am new to seeking solutions through forums, so I apologize if I have neglected to provide some vital information about my hardware.

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  • Wireless network unstable and often WPA2 protected networks just don't work

    - by Pedro
    I have an issue with my wireless network,so that the connection is working for only a few minutes, after which my browser no longer is able to load pages, even if the wireless is still active/connected. Furthermore, most of the time WPA2-personal protected networks don't work, (yesterday was the first time it worked - for a few minutes). By "don't work" I mean that it seems to successfully connect, but the browser can't load pages. I am running Ubuntu 10.10 32bit, and my wireless card is a RaLink rt3090. No changes have been done to any settings since Ubuntu was installed - networking began working on its own after the installation - but as described in first paragraph not very well.

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  • How to write a network game?

    - by TomWij
    Based on Why is so hard to develop a MMO?: Networked game development is not trivial; there are large obstacles to overcome in not only latency, but cheat prevention, state management and load balancing. If you're not experienced with writing a networked game, this is going to be a difficult learning exercise. I know the theory about sockets, servers, clients, protocols, connections and such things. Now I wonder how one can learn to write a network game: How to balance load problems? How to manage the game state? How to keep things synchronized? How to protect the communication and client from reverse engineering? How to work around latency problems? Which things should be computed local and which things on the server? ... Are there any good books, tutorials, sites, interesting articles or other questions regarding this? I'm looking for broad answers, but specific ones are fine too to learn the difference.

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  • Copying files locally on a network folder

    - by Altay_H
    I noticed that copying a large file from one location on a network drive to another location on the same network drive takes much longer than copying it locally. Instead of copying the file locally, the network computer sends the file to my remote computer, which sends it back to the same network computer. This means the files are being transferred over the network completely unnecessarily. Is there a way to fix this issue? It's becoming a real hassle to manage the video files on my network drive. Note: This is the case with both Windows and Linux (using Samba) network folders.

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  • Wired and Wireless Network Duplication

    - by Dave
    Howdy! Running into an issue when some of our client's have their laptop's connected via the wired ethernet network aswell as on the WLAN of the same network. There is know issues caused to the end clients.. BUT! Being a Managed Services Engineer i get pretty over the alerts that come through on our reports for machine's with the same hostname on the same network! We are not going to remove this monitoring because it does help a lot with detecting and stopping inferior users and things like that. So basically.. Question is, is there a way in Windows (third party programs welcome) to disable the wireless network when a wired network is connected and operational.. I know that Windows automticaly 'prefers' the wired network, however they are still both connected and therfore there is duplicate hostnames on the same network. Could also have stupid issues with DNS and things like that! Thanks!

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  • Diving into OpenStack Network Architecture - Part 2 - Basic Use Cases

    - by Ronen Kofman
      rkofman Normal rkofman 4 138 2014-06-05T03:38:00Z 2014-06-05T05:04:00Z 3 2735 15596 Oracle Corporation 129 36 18295 12.00 Clean Clean false false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} In the previous post we reviewed several network components including Open vSwitch, Network Namespaces, Linux Bridges and veth pairs. In this post we will take three simple use cases and see how those basic components come together to create a complete SDN solution in OpenStack. With those three use cases we will review almost the entire network setup and see how all the pieces work together. The use cases we will use are: 1.       Create network – what happens when we create network and how can we create multiple isolated networks 2.       Launch a VM – once we have networks we can launch VMs and connect them to networks. 3.       DHCP request from a VM – OpenStack can automatically assign IP addresses to VMs. This is done through local DHCP service controlled by OpenStack Neutron. We will see how this service runs and how does a DHCP request and response look like. In this post we will show connectivity, we will see how packets get from point A to point B. We first focus on how a configured deployment looks like and only later we will discuss how and when the configuration is created. Personally I found it very valuable to see the actual interfaces and how they connect to each other through examples and hands on experiments. After the end game is clear and we know how the connectivity works, in a later post, we will take a step back and explain how Neutron configures the components to be able to provide such connectivity.  We are going to get pretty technical shortly and I recommend trying these examples on your own deployment or using the Oracle OpenStack Tech Preview. Understanding these three use cases thoroughly and how to look at them will be very helpful when trying to debug a deployment in case something does not work. Use case #1: Create Network Create network is a simple operation it can be performed from the GUI or command line. When we create a network in OpenStack the network is only available to the tenant who created it or it could be defined as “shared” and then it can be used by all tenants. A network can have multiple subnets but for this demonstration purpose and for simplicity we will assume that each network has exactly one subnet. Creating a network from the command line will look like this: # neutron net-create net1 Created a new network: +---------------------------+--------------------------------------+ | Field                     | Value                                | +---------------------------+--------------------------------------+ | admin_state_up            | True                                 | | id                        | 5f833617-6179-4797-b7c0-7d420d84040c | | name                      | net1                                 | | provider:network_type     | vlan                                 | | provider:physical_network | default                              | | provider:segmentation_id  | 1000                                 | | shared                    | False                                | | status                    | ACTIVE                               | | subnets                   |                                      | | tenant_id                 | 9796e5145ee546508939cd49ad59d51f     | +---------------------------+--------------------------------------+ Creating a subnet for this network will look like this: # neutron subnet-create net1 10.10.10.0/24 Created a new subnet: +------------------+------------------------------------------------+ | Field            | Value                                          | +------------------+------------------------------------------------+ | allocation_pools | {"start": "10.10.10.2", "end": "10.10.10.254"} | | cidr             | 10.10.10.0/24                                  | | dns_nameservers  |                                                | | enable_dhcp      | True                                           | | gateway_ip       | 10.10.10.1                                     | | host_routes      |                                                | | id               | 2d7a0a58-0674-439a-ad23-d6471aaae9bc           | | ip_version       | 4                                              | | name             |                                                | | network_id       | 5f833617-6179-4797-b7c0-7d420d84040c           | | tenant_id        | 9796e5145ee546508939cd49ad59d51f               | +------------------+------------------------------------------------+ We now have a network and a subnet, on the network topology view this looks like this: Now let’s dive in and see what happened under the hood. Looking at the control node we will discover that a new namespace was created: # ip netns list qdhcp-5f833617-6179-4797-b7c0-7d420d84040c   The name of the namespace is qdhcp-<network id> (see above), let’s look into the namespace and see what’s in it: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 12: tap26c9b807-7c: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN     link/ether fa:16:3e:1d:5c:81 brd ff:ff:ff:ff:ff:ff     inet 10.10.10.3/24 brd 10.10.10.255 scope global tap26c9b807-7c     inet6 fe80::f816:3eff:fe1d:5c81/64 scope link        valid_lft forever preferred_lft forever   We see two interfaces in the namespace, one is the loopback and the other one is an interface called “tap26c9b807-7c”. This interface has the IP address of 10.10.10.3 and it will also serve dhcp requests in a way we will see later. Let’s trace the connectivity of the “tap26c9b807-7c” interface from the namespace.  First stop is OVS, we see that the interface connects to bridge  “br-int” on OVS: # ovs-vsctl show 8a069c7c-ea05-4375-93e2-b9fc9e4b3ca1     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-ex         Port br-ex             Interface br-ex                 type: internal     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port "tap26c9b807-7c"             tag: 1             Interface "tap26c9b807-7c"                 type: internal         Port br-int             Interface br-int                 type: internal     ovs_version: "1.11.0"   In the picture above we have a veth pair which has two ends called “int-br-eth2” and "phy-br-eth2", this veth pair is used to connect two bridge in OVS "br-eth2" and "br-int". In the previous post we explained how to check the veth connectivity using the ethtool command. It shows that the two are indeed a pair: # ethtool -S int-br-eth2 NIC statistics:      peer_ifindex: 10 . .   #ip link . . 10: phy-br-eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 . . Note that “phy-br-eth2” is connected to a bridge called "br-eth2" and one of this bridge's interfaces is the physical link eth2. This means that the network which we have just created has created a namespace which is connected to the physical interface eth2. eth2 is the “VM network” the physical interface where all the virtual machines connect to where all the VMs are connected. About network isolation: OpenStack supports creation of multiple isolated networks and can use several mechanisms to isolate the networks from one another. The isolation mechanism can be VLANs, VxLANs or GRE tunnels, this is configured as part of the initial setup in our deployment we use VLANs. When using VLAN tagging as an isolation mechanism a VLAN tag is allocated by Neutron from a pre-defined VLAN tags pool and assigned to the newly created network. By provisioning VLAN tags to the networks Neutron allows creation of multiple isolated networks on the same physical link.  The big difference between this and other platforms is that the user does not have to deal with allocating and managing VLANs to networks. The VLAN allocation and provisioning is handled by Neutron which keeps track of the VLAN tags, and responsible for allocating and reclaiming VLAN tags. In the example above net1 has the VLAN tag 1000, this means that whenever a VM is created and connected to this network the packets from that VM will have to be tagged with VLAN tag 1000 to go on this particular network. This is true for namespace as well, if we would like to connect a namespace to a particular network we have to make sure that the packets to and from the namespace are correctly tagged when they reach the VM network. In the example above we see that the namespace interface “tap26c9b807-7c” has vlan tag 1 assigned to it, if we examine OVS we see that it has flows which modify VLAN tag 1 to VLAN tag 1000 when a packet goes to the VM network on eth2 and vice versa. We can see this using the dump-flows command on OVS for packets going to the VM network we see the modification done on br-eth2: #  ovs-ofctl dump-flows br-eth2 NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18669.401s, table=0, n_packets=857, n_bytes=163350, idle_age=25, priority=4,in_port=2,dl_vlan=1 actions=mod_vlan_vid:1000,NORMAL  cookie=0x0, duration=165108.226s, table=0, n_packets=14, n_bytes=1000, idle_age=5343, hard_age=65534, priority=2,in_port=2 actions=drop  cookie=0x0, duration=165109.813s, table=0, n_packets=1671, n_bytes=213304, idle_age=25, hard_age=65534, priority=1 actions=NORMAL   For packets coming from the interface to the namespace we see the following modification: #  ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18690.876s, table=0, n_packets=1610, n_bytes=210752, idle_age=1, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL  cookie=0x0, duration=165130.01s, table=0, n_packets=75, n_bytes=3686, idle_age=4212, hard_age=65534, priority=2,in_port=1 actions=drop  cookie=0x0, duration=165131.96s, table=0, n_packets=863, n_bytes=160727, idle_age=1, hard_age=65534, priority=1 actions=NORMAL   To summarize we can see that when a user creates a network Neutron creates a namespace and this namespace is connected through OVS to the “VM network”. OVS also takes care of tagging the packets from the namespace to the VM network with the correct VLAN tag and knows to modify the VLAN for packets coming from VM network to the namespace. Now let’s see what happens when a VM is launched and how it is connected to the “VM network”. Use case #2: Launch a VM Launching a VM can be done from Horizon or from the command line this is how we do it from Horizon: Attach the network: And Launch Once the virtual machine is up and running we can see the associated IP using the nova list command : # nova list +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | ID                                   | Name         | Status | Task State | Power State | Networks        | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | 3707ac87-4f5d-4349-b7ed-3a673f55e5e1 | Oracle Linux | ACTIVE | None       | Running     | net1=10.10.10.2 | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ The nova list command shows us that the VM is running and that the IP 10.10.10.2 is assigned to this VM. Let’s trace the connectivity from the VM to VM network on eth2 starting with the VM definition file. The configuration files of the VM including the virtual disk(s), in case of ephemeral storage, are stored on the compute node at/var/lib/nova/instances/<instance-id>/. Looking into the VM definition file ,libvirt.xml,  we see that the VM is connected to an interface called “tap53903a95-82” which is connected to a Linux bridge called “qbr53903a95-82”: <interface type="bridge">       <mac address="fa:16:3e:fe:c7:87"/>       <source bridge="qbr53903a95-82"/>       <target dev="tap53903a95-82"/>     </interface>   Looking at the bridge using the brctl show command we see this: # brctl show bridge name     bridge id               STP enabled     interfaces qbr53903a95-82          8000.7e7f3282b836       no              qvb53903a95-82                                                         tap53903a95-82    The bridge has two interfaces, one connected to the VM (“tap53903a95-82 “) and another one ( “qvb53903a95-82”) connected to “br-int” bridge on OVS: # ovs-vsctl show 83c42f80-77e9-46c8-8560-7697d76de51c     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-int         Port br-int             Interface br-int                 type: internal         Port "int-br-eth2"             Interface "int-br-eth2"         Port "qvo53903a95-82"             tag: 3             Interface "qvo53903a95-82"     ovs_version: "1.11.0"   As we showed earlier “br-int” is connected to “br-eth2” on OVS using the veth pair int-br-eth2,phy-br-eth2 and br-eth2 is connected to the physical interface eth2. The whole flow end to end looks like this: VM è tap53903a95-82 (virtual interface)è qbr53903a95-82 (Linux bridge) è qvb53903a95-82 (interface connected from Linux bridge to OVS bridge br-int) è int-br-eth2 (veth one end) è phy-br-eth2 (veth the other end) è eth2 physical interface. The purpose of the Linux Bridge connecting to the VM is to allow security group enforcement with iptables. Security groups are enforced at the edge point which are the interface of the VM, since iptables nnot be applied to OVS bridges we use Linux bridge to apply them. In the future we hope to see this Linux Bridge going away rules.  VLAN tags: As we discussed in the first use case net1 is using VLAN tag 1000, looking at OVS above we see that qvo41f1ebcf-7c is tagged with VLAN tag 3. The modification from VLAN tag 3 to 1000 as we go to the physical network is done by OVS  as part of the packet flow of br-eth2 in the same way we showed before. To summarize, when a VM is launched it is connected to the VM network through a chain of elements as described here. During the packet from VM to the network and back the VLAN tag is modified. Use case #3: Serving a DHCP request coming from the virtual machine In the previous use cases we have shown that both the namespace called dhcp-<some id> and the VM end up connecting to the physical interface eth2  on their respective nodes, both will tag their packets with VLAN tag 1000.We saw that the namespace has an interface with IP of 10.10.10.3. Since the VM and the namespace are connected to each other and have interfaces on the same subnet they can ping each other, in this picture we see a ping from the VM which was assigned 10.10.10.2 to the namespace: The fact that they are connected and can ping each other can become very handy when something doesn’t work right and we need to isolate the problem. In such case knowing that we should be able to ping from the VM to the namespace and back can be used to trace the disconnect using tcpdump or other monitoring tools. To serve DHCP requests coming from VMs on the network Neutron uses a Linux tool called “dnsmasq”,this is a lightweight DNS and DHCP service you can read more about it here. If we look at the dnsmasq on the control node with the ps command we see this: dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap26c9b807-7c --except-interface=lo --pid-file=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host --dhcp-optsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/opts --leasefile-ro --dhcp-range=tag0,10.10.10.0,static,120s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal The service connects to the tap interface in the namespace (“--interface=tap26c9b807-7c”), If we look at the hosts file we see this: # cat  /var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host fa:16:3e:fe:c7:87,host-10-10-10-2.openstacklocal,10.10.10.2   If you look at the console output above you can see the MAC address fa:16:3e:fe:c7:87 which is the VM MAC. This MAC address is mapped to IP 10.10.10.2 and so when a DHCP request comes with this MAC dnsmasq will return the 10.10.10.2.If we look into the namespace at the time we initiate a DHCP request from the VM (this can be done by simply restarting the network service in the VM) we see the following: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c tcpdump -n 19:27:12.191280 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from fa:16:3e:fe:c7:87, length 310 19:27:12.191666 IP 10.10.10.3.bootps > 10.10.10.2.bootpc: BOOTP/DHCP, Reply, length 325   To summarize, the DHCP service is handled by dnsmasq which is configured by Neutron to listen to the interface in the DHCP namespace. Neutron also configures dnsmasq with the combination of MAC and IP so when a DHCP request comes along it will receive the assigned IP. Summary In this post we relied on the components described in the previous post and saw how network connectivity is achieved using three simple use cases. These use cases gave a good view of the entire network stack and helped understand how an end to end connection is being made between a VM on a compute node and the DHCP namespace on the control node. One conclusion we can draw from what we saw here is that if we launch a VM and it is able to perform a DHCP request and receive a correct IP then there is reason to believe that the network is working as expected. We saw that a packet has to travel through a long list of components before reaching its destination and if it has done so successfully this means that many components are functioning properly. In the next post we will look at some more sophisticated services Neutron supports and see how they work. We will see that while there are some more components involved for the most part the concepts are the same. @RonenKofman

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  • Multiuser's impact on Access Database

    - by SilentRage47
    Can someone explain to me how are effected the performances of an Access 2003 DB when it's used by a lot (30) of users on the same LAN? I'm working on a vb6 project with this access 2003 DB wich performs ok on my local PC, but it's terrible when used across 20-30 users. It's there something I can do to improve performance? How can I understand what's the cause of this degradation in performance?

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