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  • Windows 7 "Could not reconnect all network drives" on boot

    - by Thermionix
    Windows 7 won't reconnect to my network drives on startup. Once it is done booting opening Windows Explorer and clicking each share will mount them. Windows 7 Enterprise N Service Pack 1 I have attempted formatting the windows machine - first thing done to machine was to map the network drives, upon reboot they were disconnected. It is running on an Crucial M4 64gb SSD. The host of the network shares is a Ubuntu-Server machine connected through a gigabit switch. A modem provides dhcp, although both these machines have static IP's defined. It won't reconnect the drives regardless of whether they're SAMBA shares or NFS shares - therefore I believe it's an issue with the windows machine. Ubuntu 11.10 (GNU/Linux 3.0.0-12-server x86_64) I've tried using ip address instead of netbios name for mapping shares on the windows machine, Also tried setting EnableLinkedConnections=1 gpedit.msc Computer Configuration - Administrative Templates - System-Logon - always wait for the network at computer startup and logon = yes

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  • Determine who is opening a .PST file from a network drive on the local network?

    - by hypoxide
    Our system admin has been struggling with the issue of our network getting completely locked up when users open PST files from network drives. Apparently Microsoft is aware of this problem but there is no fix for it. The entire local network is unable to use Outlook while this file is being opened (which may take hours). Is there a way to determine which user is opening the file instead of forcing everyone in the office to close outlook (like a traffic monitor or something)?

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  • Recurring network issues the same time every day.

    - by Peter Turner
    Something has been happening on my company's network at 9:30 every day. I'm not the sysadmin but he's not a ServerFault guy so I'm not privy to every aspect of the network but I can ask questions if follow up is needed. The symptoms are the following : Sluggish network and download speed (I don't notice it, but others do) 3Com phones start ringing without having people on the other end. We've got the following ports exposed to the public for a web server, a few other ports for communicating with our clients for tech support and a VPN. We've got a Cisco ASA blocking everything else. We've got a smallish network (less than 50 computers/vms on at any time). An Active Directory server and a few VM servers. We host our own mail server too. I'm thinking the problem is internal, but what's a good way to figure out where it's coming from?

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  • Windows 7 / TCP/IP network share guide - looking for to resolve failure to mount lacie network drive but works on XP,Linux,Mac.

    - by Rob
    Can anyone advise me of a really good, readable, Windows 7 TCP/IP network share guide, book, or reference. I want this because I cannot mount my Lacie 2big ethernet network drive in Windows 7 (32 bit home), but I can mount it in Windows XP Home 32bit, Ubuntu Linux 10.04 and Apple MacOS X. This drive is being mounted via the accompanying Lacie Ethernet Agent in XP (which I believe uses "Bonjour" protocol), on Mac and Linux it works without further need for software. Another Super User user has the same problem, but no answer: Trouble accessing network drives in Windows 7 I hope my take on the question shows a better willingness to investigate and do some digging - and therefore invite some suggestions to help with this. The drive is detected by Windows 7 (i.e. speech bubble "network drive found") but on trying to open an Explorer window, this remains blank with the Windows busy pointer. I'd prefer not to reinstall Windows 7 to see if that cures the problem, I'd rather understand what is happening/not happening, perhaps even compare differences with Windows XP. Suggestions, please for such guides or even the original problem itself. Update Edit Rewrote question more comprehensively here: Mhttp://superuser.com/questions/304209/looking-for-definitive-answer-to-accessing-a-network-share-via-windows-7-home-and

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  • Linux - Network Sharing a local NTFS usb drive

    - by Jonathan Rioux
    I have an external hard drive formated in NTFS which I would like to be able to access by the network. I want to make a network share out of it. I also have a Debian machine running in my house and I then got an idea. I want to plug in my external hard drive (usb) into my Debian machine, and make a windows share with it, maybe with Samba, so I will be able to access it from my Windows 7 laptop and see it as a network share. Additionally, how can I restrict specific folders of that network share, and allow only specific folders to specific users? For instance, I would like to give my girlfriend access to a folder of her name so she can put her files and so she wont be able to see the stuff in my folder...

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  • Can't copy files from network drive

    - by user630320
    I have weird problem with copying files. When I copy file from network drive into C drive nothing happens but when I copy file from network drive to desktop I can copy the file. Also if I copy files from desktop into C it works fine. I have full local admin permission on this PC and the network drive. I have try these things Created new profile Run Windows Update Run checkdisk I'm using Windows XP 32bit pro Update: Network path: \\server1\shared\folder PC: C:\ (this doesn't work) C:\Documents and settings\Userid\Desktop (This works fine)

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  • Linux browse and open network files with command line

    - by user3077066
    I'm new to Linux. I have a Windows network connected to a Linux computer. When I try to browse Windows files from windows managers in Linux, it asks for user name, work group name and password. The address of computer network is something like this: smb://computer-name/folder I want to access my network folders and files using command line. I have searched a little bit but I didn't find anything. Any suggestions? Thanks in advance

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  • How can I monitor network traffic in an all Mac home network?

    - by raiglstorfer
    I have an all Mac network consisting of an Airport Extreme, 1 MacPro, 1 Mac Mini, 2 MackBook Pros, 2 iPads, and 2 iPhones. The Mac Pro is connected directly to the Airport Extreme via Cat5 and the rest is all running via Wireless. Lately I've been getting prompted by Google to enter Capchas frequently. The message states that I might have software running on my network I'm not aware of. My wireless router is password protected using WPA2 Personal and I frequently change my password so I don't think someone is using the network from outside (but I've no way to confirm this). I'm looking for a relatively cheap (preferably open source) solution that would enable me to monitor and profile the network usage by machine and port. Can someone recommend a solution?

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  • How can I monitor network traffic in an all Mac home network?

    - by raiglstorfer
    I have an all Mac network consisting of an Airport Extreme, 1 MacPro, 1 Mac Mini, 2 MackBook Pros, 2 iPads, and 2 iPhones. The Mac Pro is connected directly to the Airport Extreme via Cat5 and the rest is all running via Wireless. Lately I've been getting prompted by Google to enter Capchas frequently. The message states that I might have software running on my network I'm not aware of. My wireless router is password protected using WPA2 Personal and I frequently change my password so I don't think someone is using the network from outside (but I've no way to confirm this). I'm looking for a relatively cheap (preferably open source) solution that would enable me to monitor and profile the network usage by machine and port. Can someone recommend a solution?

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  • Isolated Network Set-Up

    - by Isaac Kleinman
    I am looking to set up a small network for a client which would be isolated from his primary network. (I'm hoping to set-up the additional network as VMs on the primary network.) I've instructed the client to request a bunch of static ip addresses from his ISP, but I'm not sure how to proceed with setting this up. What hardware will I need and how do I go about the configuration? Heavy security is not my concern. All that's really required is that web requests from the two networks be presented to the outside world with different ip addresses.

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  • SharePoint 2010 Video - Business Connectivity Services

    - by Sahil Malik
    Ad:: SharePoint 2007 Training in .NET 3.5 technologies (more information). The latest DNRTV episode on SharePoint 2010 Business Connectivity Services is now online. This is a video we (Carl and I) had recorded back in April 2010, and is a sneak peak to the SharePoint 2010 DVD that is finally on sale. Hope you like both. Comment on the article ....

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  • Why does Network-Manager close when it cannot bind to any connection?

    - by Agmenor
    When Network-Manager is not able to bind my Ubuntu to any connection, after a while it closes. The icon in the notification area (or indicator area) disappears, and it does not run any more. For instance this happens when there is really no ethernet network nor wireless one. Nonetheless this is a problem, since I often plug in my ethernet cable long after having booted my computer. As a hack I therefore hit Alt + F2, and type nm-applet. But I am not satisfied with this solution, because I think it is not intuitive enough. Is there a way to keep Network-Manager always running? I have Network-Manager 0.8.1 on Ubuntu 10.10, but this has been so for a long time, at least for one year.

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  • Network doesn't work after installing Ubuntu 10.10. Is this a hardware failure?

    - by Septagram
    Recently I installed Ubuntu 10.10 on my dev box, making a dual boot with Windows XP. Before installation, everything worked fine, but now Windows XP cannot connect to the network saying that cable is not connected. I tried connecting it to different devices, and it always fails. Under Ubuntu I observe the same issue, but occasionally, usually it works and sometimes it can't find the network. Do you people think it's Ubuntu related, or is my network card broken?

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  • Lost connectivity after configuring multiple network adapters on separate networks

    - by Dave Long
    I am trying to setup an Ubuntu hosting server, currently just for development, and the server has two NICs, each sitting on a different network. eth0 is on 192.168.200.* and eth1 is on 192.168.101.* and each one has a static IP. eth0 is the public facing NIC card and eth1 is strictly for internal access to the server. I initially only setup eth0 and added the eth1 card when I needed it. eth0 was working find until I added eth1, now, can't get any connectivity on eth0 unless I pull eth1 out of the box. The configuration on each system is as follows: auto eth0 iface eth0 inet static address 192.168.200.94 netmask 255.255.255.0 network 192.168.200.0 broadcast 192.168.200.255 gateway 192.168.200.253 auto eth1 iface eth1 inet static address 192.168.101.64 netmask 255.255.255.0 network 192.168.101.0 broadcast 192.168.101.255 gateway 192.168.101.254 Again eth0 worked fine until I added eth1. I have seen this happen with Windows servers if you have a Default Gateway setup for both NICs, but I am not sure if this works the same on Ubuntu. My resolv.conf file looks like so: nameserver 192.168.101.59 nameserver 192.168.101.58 domain domain.local search domain.local Per request here is the Routing table 192.168.101.0 * 255.255.255.0 U 0 0 0 eth1 192.168.200.0 * 255.255.255.0 U 0 0 0 eth0 default 192.168.101.254 0.0.0.0 UG 100 0 0 eth1 default 192.168.200.253 0.0.0.0 UG 100 0 0 eth0

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  • Ultrabooks and projectors: is there any connectivity issue due to low power on video output? [closed]

    - by sergey
    I need to buy a new laptop for my wife. She travels a lot and I was thinking about an ultrabook (1.5-2 kg). However she says that ultrabooks have problems connecting to projectors. At least some of her colleagues could not connect their ultrabooks to projectors due to “low output issues”. She is in-company consultant and trainer and for her “be able to connect to any client projector” requirement is must. Thus my doubts are: Is this problem well known? Is there any chance to assure connectivity to projector (by checking some specification before buy, etc)?

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  • The Interaction between Three-Tier Client/Server Model and Three-Tier Application Architecture Model

    The three-tier client/server model is a network architectural approach currently used in modern networking. This approach divides a network in to three distinct components. Three-Tier Client/Server Model Components Client Component Server Component Database Component The Client Component of the network typically represents any device on the network. A basic example of this would be computer or another network/web enabled devices that are connected to a network. Network clients request resources on the network, and are usually equipped with a user interface for the presentation of the data returned from the Server Component. This process is done through the use of various software clients, and example of this can be seen through the use of a web browser client. The web browser request information from the Server Component located on the network and then renders the results for the user to process. The Server Components of the network return data based on specific client request back to the requesting client.  Server Components also inherit the attributes of a Client Component in that they are a device on the network and that they can also request information from other Server Components. However what differentiates a Client Component from a Server Component is that a Server Component response to requests from devices on the network. An example of a Server Component can be seen in a web server. A web server listens for new requests and then interprets the request, processes the web pages, and then returns the processed data back to the web browser client so that it may render the data for the user to interpret. The Database Component of the network returns unprocessed data from databases or other resources. This component also inherits attributes from the Server Component in that it is a device on a network, it can request information from other server components and database components, and it also listens for new requests so that it can return data when needed. The three-tier client/server model is very similar to the three-tier application architecture model, and in fact the layers can be mapped to one another. Three-Tier Application Architecture Model Presentation Layer/Logic Business Layer/Logic Data Layer/Logic The Presentation Layer including its underlying logic is very similar to the Client Component of the three-tiered model. The Presentation Layer focuses on interpreting the data returned by the Business Layer as well as presents the data back to the user.  Both the Presentation Layer and the Client Component focus primarily on the user and their experience. This allows for segments of the Business Layer to be distributable and interchangeable because the Presentation Layer is not directly integrated in with Business Layer. The Presentation Layer does not care where the data comes from as long as it is in the proper format. This allows for the Presentation Layer and Business Layer to be stored on one or more different servers so that it can provide a higher availability to clients requesting data. A good example of this is a web site that uses load balancing. When a web site decides to take on the task of load balancing they must obtain a network device that sits in front of a one or machines in order to distribute the request across multiple servers. When a user comes in through the load balanced device they are redirected to a specific server based on a few factors. Common Load Balancing Factors Current Server Availability Current Server Response Time Current Server Priority The Business Layer and corresponding logic are business rules applied to data prior to it being sent to the Presentation Layer. These rules are used to manipulate the data coming from the Data Access Layer, in addition to validating any data prior to being stored in the Data Access Layer. A good example of this would be when a user is trying to create multiple accounts under one email address. The Business Layer logic can prevent duplicate accounts by enforcing a unique email for every new account before the data is even stored in the Data Access Layer. The Server Component can be directly tied to this layer in that the server typically stores and process the Business Layer before it is returned to the end-user via the Presentation Layer. In addition the Server Component can also run automated process through the Business Layer on the data in the Data Access Layer so that additional business analysis can be derived from the data that has been already collected. The Data Layer and its logic are responsible for storing information so that it can be easily retrieved. Typical in most modern applications data is stored in a database management system however data can also be in the form of files stored on a file server. In addition a database can take on one of several forms. Common Database Formats XML File Pipe Delimited File Tab Delimited File Comma Delimited File (CSV) Plain Text File Microsoft Access Microsoft SQL Server MySql Oracle Sybase The Database component of the Networking model can be directly tied to the Data Layer because this is where the Data Layer obtains the data to return back the Business Layer. The Database Component basically allows for a place on the network to store data for future use. This enables applications to save data when they can and then quickly recall the saved data as needed so that the application does not have to worry about storing the data in memory. This prevents overhead that could be created when an application must retain all data in memory. As you can see the Three-Tier Client/Server Networking Model and the Three-Tiered Application Architecture Model rely very heavily on one another to function especially if different aspects of an application are distributed across an entire network. The use of various servers and database servers are wonderful when an application has a need to distribute work across the network. Network Components and Application Layers Interaction Database components will store all data needed for the Data Access Layer to manipulate and return to the Business Layer Server Component executes the Business Layer that manipulates data so that it can be returned to the Presentation Layer Client Component hosts the Presentation Layer that  interprets the data and present it to the user

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  • Wired and Wireless USB Network Adapter

    - by Evan M.
    Does anyone know if there are any USB network adapters out there that have both wired and wireless networking capability? Far-fetched, I know, but thought I'd ask. Background: Some of our users have locked down laptops that we also include unlocked virtual machines running on VMware Player. Sometimes the users have a need for network connectivity with their VMs where NAT and bridged networking from the host won't work. To supplement this, we want to supply them with adapters that they can use VMware USB pass through capabilities to provide appropriate connectivity. They will need both wired and wireless capability. Rather than carrying around 2 adapters, was hoping we could get a combination unit so that we can reduce it to 1. Thanks

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  • I have to make a simple app that connects devices in a network, but I have no idea of how to this

    - by Gabriel Casado
    I want to write an App for android that has only one ListView. The App will constantly search for anything (mobile devices, desktops, etc.) that is connected in the wifi network. The problem is, I have no idea how to do this. What do I need to study? I comprehend I'd need to use a Thread or a Runnable to constantly search for those devices. Also I know very little about TCP, UDP or any internet protocols. So, can someone give me a basis of what I need to learn to develop this App?

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  • SARA Security Auditor Alternative

    - by bradlis7
    I have attempted to install and run Sara, but it seems that the software is broken. I could get it to run on 127.0.0.1, but it seems that no network packets ever leave the current computer that it is installed on. It tests for known security holes in a network. It was based on an older software SATAN. Is there another free alternative to this program? I did not see anything listed in this thread.

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  • Diving into OpenStack Network Architecture - Part 1

    - by Ronen Kofman
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} rkofman Normal rkofman 83 3045 2014-05-23T21:11:00Z 2014-05-27T06:58:00Z 3 1883 10739 Oracle Corporation 89 25 12597 12.00 140 Clean Clean false false false false EN-US X-NONE HE MicrosoftInternetExplorer4 /* 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;} Before we begin OpenStack networking has very powerful capabilities but at the same time it is quite complicated. In this blog series we will review an existing OpenStack setup using the Oracle OpenStack Tech Preview and explain the different network components through use cases and examples. The goal is to show how the different pieces come together and provide a bigger picture view of the network architecture in OpenStack. This can be very helpful to users making their first steps in OpenStack or anyone wishes to understand how networking works in this environment.  We will go through the basics first and build the examples as we go. According to the recent Icehouse user survey and the one before it, Neutron with Open vSwitch plug-in is the most widely used network setup both in production and in POCs (in terms of number of customers) and so in this blog series we will analyze this specific OpenStack networking setup. As we know there are many options to setup OpenStack networking and while Neturon + Open vSwitch is the most popular setup there is no claim that it is either best or the most efficient option. Neutron + Open vSwitch is an example, one which provides a good starting point for anyone interested in understanding OpenStack networking. Even if you are using different kind of network setup such as different Neutron plug-in or even not using Neutron at all this will still be a good starting point to understand the network architecture in OpenStack. The setup we are using for the examples is the one used in the Oracle OpenStack Tech Preview. Installing it is simple and it would be helpful to have it as reference. In this setup we use eth2 on all servers for VM network, all VM traffic will be flowing through this interface.The Oracle OpenStack Tech Preview is using VLANs for L2 isolation to provide tenant and network isolation. The following diagram shows how we have configured our deployment: This first post is a bit long and will focus on some basic concepts in OpenStack networking. The components we will be discussing are Open vSwitch, network namespaces, Linux bridge and veth pairs. Note that this is not meant to be a comprehensive review of these components, it is meant to describe the component as much as needed to understand OpenStack network architecture. All the components described here can be further explored using other resources. Open vSwitch (OVS) In the Oracle OpenStack Tech Preview OVS is used to connect virtual machines to the physical port (in our case eth2) as shown in the deployment diagram. OVS contains bridges and ports, the OVS bridges are different from the Linux bridge (controlled by the brctl command) which are also used in this setup. To get started let’s view the OVS structure, use the following command: # ovs-vsctl show 7ec51567-ab42-49e8-906d-b854309c9edf     Bridge br-int         Port br-int             Interface br-int type: internal         Port "int-br-eth2"             Interface "int-br-eth2"     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2" ovs_version: "1.11.0" We see a standard post deployment OVS on a compute node with two bridges and several ports hanging off of each of them. The example above is a compute node without any VMs, we can see that the physical port eth2 is connected to a bridge called “br-eth2”. We also see two ports "int-br-eth2" and "phy-br-eth2" which are actually a veth pair and form virtual wire between the two bridges, veth pairs are discussed later in this post. When a virtual machine is created a port is created on one the br-int bridge and this port is eventually connected to the virtual machine (we will discuss the exact connectivity later in the series). Here is how OVS looks after a VM was launched: # ovs-vsctl show efd98c87-dc62-422d-8f73-a68c2a14e73d     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port br-int             Interface br-int type: internal         Port "qvocb64ea96-9f" tag: 1             Interface "qvocb64ea96-9f"     Bridge "br-eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2" ovs_version: "1.11.0" Bridge "br-int" now has a new port "qvocb64ea96-9f" which connects to the VM and tagged with VLAN 1. Every VM which will be launched will add a port on the “br-int” bridge for every network interface the VM has. Another useful command on OVS is dump-flows for example: # ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4): cookie=0x0, duration=735.544s, table=0, n_packets=70, n_bytes=9976, idle_age=17, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL cookie=0x0, duration=76679.786s, table=0, n_packets=0, n_bytes=0, idle_age=65534, hard_age=65534, priority=2,in_port=1 actions=drop cookie=0x0, duration=76681.36s, table=0, n_packets=68, n_bytes=7950, idle_age=17, hard_age=65534, priority=1 actions=NORMAL As we see the port which is connected to the VM has the VLAN tag 1. However the port on the VM network (eth2) will be using tag 1000. OVS is modifying the vlan as the packet flow from the VM to the physical interface. In OpenStack the Open vSwitch agent takes care of programming the flows in Open vSwitch so the users do not have to deal with this at all. If you wish to learn more about how to program the Open vSwitch you can read more about it at http://openvswitch.org looking at the documentation describing the ovs-ofctl command. Network Namespaces (netns) Network namespaces is a very cool Linux feature can be used for many purposes and is heavily used in OpenStack networking. Network namespaces are isolated containers which can hold a network configuration and is not seen from outside of the namespace. A network namespace can be used to encapsulate specific network functionality or provide a network service in isolation as well as simply help to organize a complicated network setup. Using the Oracle OpenStack Tech Preview we are using the latest Unbreakable Enterprise Kernel R3 (UEK3), this kernel provides a complete support for netns. Let's see how namespaces work through couple of examples to control network namespaces we use the ip netns command: Defining a new namespace: # ip netns add my-ns # ip netns list my-ns As mentioned the namespace is an isolated container, we can perform all the normal actions in the namespace context using the exec command for example running the ifconfig command: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:16436 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) We can run every command in the namespace context, this is especially useful for debug using tcpdump command, we can ping or ssh or define iptables all within the namespace. Connecting the namespace to the outside world: There are various ways to connect into a namespaces and between namespaces we will focus on how this is done in OpenStack. OpenStack uses a combination of Open vSwitch and network namespaces. OVS defines the interfaces and then we can add those interfaces to namespace. So first let's add a bridge to OVS: # ovs-vsctl add-br my-bridge Now let's add a port on the OVS and make it internal: # ovs-vsctl add-port my-bridge my-port # ovs-vsctl set Interface my-port type=internal And let's connect it into the namespace: # ip link set my-port netns my-ns Looking inside the namespace: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:65536 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) my-port   Link encap:Ethernet HWaddr 22:04:45:E2:85:21           BROADCAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) Now we can add more ports to the OVS bridge and connect it to other namespaces or other device like physical interfaces. Neutron is using network namespaces to implement network services such as DCHP, routing, gateway, firewall, load balance and more. In the next post we will go into this in further details. Linux Bridge and veth pairs Linux bridge is used to connect the port from OVS to the VM. Every port goes from the OVS bridge to a Linux bridge and from there to the VM. The reason for using regular Linux bridges is for security groups’ enforcement. Security groups are implemented using iptables and iptables can only be applied to Linux bridges and not to OVS bridges. Veth pairs are used extensively throughout the network setup in OpenStack and are also a good tool to debug a network problem. Veth pairs are simply a virtual wire and so veths always come in pairs. Typically one side of the veth pair will connect to a bridge and the other side to another bridge or simply left as a usable interface. In this example we will create some veth pairs, connect them to bridges and test connectivity. This example is using regular Linux server and not an OpenStack node: Creating a veth pair, note that we define names for both ends: # ip link add veth0 type veth peer name veth1 # ifconfig -a . . veth0     Link encap:Ethernet HWaddr 5E:2C:E6:03:D0:17           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) veth1     Link encap:Ethernet HWaddr E6:B6:E2:6D:42:B8           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) . . To make the example more meaningful this we will create the following setup: veth0 => veth1 => br-eth3 => eth3 ======> eth2 on another Linux server br-eth3 – a regular Linux bridge which will be connected to veth1 and eth3 eth3 – a physical interface with no IP on it, connected to a private network eth2 – a physical interface on the remote Linux box connected to the private network and configured with the IP of 50.50.50.1 Once we create the setup we will ping 50.50.50.1 (the remote IP) through veth0 to test that the connection is up: # brctl addbr br-eth3 # brctl addif br-eth3 eth3 # brctl addif br-eth3 veth1 # brctl show bridge name     bridge id               STP enabled     interfaces br-eth3         8000.00505682e7f6       no              eth3                                                         veth1 # ifconfig veth0 50.50.50.50 # ping -I veth0 50.50.50.51 PING 50.50.50.51 (50.50.50.51) from 50.50.50.50 veth0: 56(84) bytes of data. 64 bytes from 50.50.50.51: icmp_seq=1 ttl=64 time=0.454 ms 64 bytes from 50.50.50.51: icmp_seq=2 ttl=64 time=0.298 ms When the naming is not as obvious as the previous example and we don't know who are the paired veth interfaces we can use the ethtool command to figure this out. The ethtool command returns an index we can look up using ip link command, for example: # ethtool -S veth1 NIC statistics: peer_ifindex: 12 # ip link . . 12: veth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 Summary That’s all for now, we quickly reviewed OVS, network namespaces, Linux bridges and veth pairs. These components are heavily used in the OpenStack network architecture we are exploring and understanding them well will be very useful when reviewing the different use cases. In the next post we will look at how the OpenStack network is laid out connecting the virtual machines to each other and to the external world. @RonenKofman

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  • Persistent Issues on small business network using Cisco 871W and Catalyst Express 500

    - by Ben Campbell
    Being the most qualified (read: still not qualified) to solve our persistant network issues, I've turned to serverfault for guidance. I've done some searching, reading related documentation on cisco.com and tried a bit of troubleshooting. Here is the config: 100mb synchronous connection from a business internet provider (tested multiple times at 100meg at the source) Cisco 871W wireless point & router is where the WAN connection starts (this serves all our wireless). The only wired connection in the 871W is the Catalyst switch listed below. Cisco Catalyst Express 500 (24TT) is where all the wired connections terminate. About 20 Windows workstations and servers (AD/Webservers only). Some services in EC2 including mail and other web servers/apps. I've been TOLD cabling internally should be gigabit-ready. Here are the problems: generally slow download rates from the internet to the desktop/laptop frequent "page cannot be displayed" errors in browsers-sometimes 3 or 4 reloads are necessary... often times CSS wont load or other content requiring the browser to connect to a different server. slow speed within the LAN from workstation to workstation copying files. I would expect extremely fast data transfer workstation to workstation / server to workstation in this simple network. Several things I need to admit: I'm not primarily a network guy. Funding is relatively low, I need to be the guy that finds the solution. I understand most of the terminology and most of the technology. Implementation is where I fail due to lack of experience. Getting to the point: I'm wondering whether experienced network admins think that our small network should be sufficiently served with our current hardware if configured properly... or if we should purchase new equipment and start fresh? If starting fresh is the plan, whatever that new equipment may be is a likely different question entirely. If I haven't provided enough information, I will happily do some troubleshooting and update with the results. I have experience using wireshark and some other tools. Please let me know what you think would be most helpful and thanks in advance. EDIT: I forgot to add that the Cisco applicance will not finish loading the SDM Express console. It hangs every time at the "populating modules... DHCP". It eventually crashes and closes. I've rebooted the hardware and this still happens.

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  • Share 3G connection over WiFi-LAN network

    - by kush.impetus
    This is how I have established network between my PC and my laptop at home (being novice in networking, it took me few days to achieve the feat). And it is working perfectly. I can easily share files between them. Laptop IP Address: 192.168.1.4 Subnet mask: 255.255.255.0 Default Gateway: 192.168.1.2 Desktop IP Address: 192.168.1.5 Subnet mask: 255.255.255.0 Default Gateway: 192.168.1.2 ASUS RT-N10+ Router IP Address: 192.168.1.4 Default Gateway: 192.168.1.2 I have connected the Desktop PC to the router using a LAN cable, and laptop to router over WiFi. Both, PC and laptop are running on Windows 7 OS, are on same HomeGroup, have same username / password. Also, I have connected the Ethernet cable to LAN port 1 of the router. Click here to view a graphical representation of the network. Can't post image here, because I don't have 10 reputation points. Now, what I want is use connect to Internet using a 3G USB modem on one device and share it over the network on the other. I tried Huawei and Micromax 3G USB modem. Both obtain a new IP address whenever I connect to Internet (means they have dynamic IPs). Rest, both have Subnet Mask as 255.255.255.255 and Default Gateway as 0.0.0.0. In that case, I cannot directly share Internet from the modem. Preferred DNS is blank for now in both, laptop and PC. What I am planning to do is to connect to Internet on laptop using the 3G modem and share the Internet connection over laptop's Wi-Fi (as hotspot) using Connectify, which I have done already. That, I suppose, will broadcast a static IP to connect to. Now what I can't figure out is that what changes should I make to the network settings of the router and the PC so that PC connects to the Internet broadcast by Connectify? Is that possible on the first hand? Please note that I am trying to implement the network without spending anything extra (for purchasing as USB WiFi adapter for PC, of course, which could have made the life lot easier for me). Thanks in advance

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  • RoboCopy fails with "the specified network name is no longer available"

    - by Justin Scott
    We have a scheduled task that runs robocopy periodically to mirror a rather large folder structure from one server to another (thousands of folders, 100,000+ files, 50+ GB in size). There is a share on the receiving server where the mirror gets stored. We're running the task from the origin server connecting out to the share on the receiving end. Both servers run Windows Server 2003 and are connected to the same network switch (100Mbps). The process will sometimes complete all the way through without error. More often than not, however, at some point during the process (seems random as to where), robocopy will fail with the error The specified network name is no longer available. It will wait 30 seconds and try the file again and eventually give up after a number of retries. Process will repeat at the next schedule interval and may complete... or not. When this occurs I am not able to access the share at all on the destination server from anywhere on the network for up to 30 minutes. There is nothing else on the network using this share. My question is what does this error mean specifically? Why is the share "dropping off" and becoming inaccessible? Is there a way to prevent it and get the file mirroring to be more stable?

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