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  • Why would you use EAP-TTLS instead of PEAP?

    - by Ivan Macek
    As I understood EAP-TTLS and PEAP share same level of security when implemented in wireless networks. Both only provide server side authentication via certificate. The drawback of EAP-TTLS can be non native support in Microsoft Windows so every user has to install additional software. The benefit of EAP-TTLS can be support for less secure authentication mechanisms (PAP, CHAP, MS-CHAP) but why would you need them in modern and properly secure wireless system? What are you opinions? Why should I implement EAP-TTLS instead of PEAP? Let's say that I have most Windows users, medium Linux users and least iOS, OSX users.

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  • Why is my Wifi connection slower than ethernet even though bandwidth should saturated?

    - by supercheetah
    I'm wondering why it is that my wireless connection is slower than my wired connection for things going to the outside world (so, not files being transferred within the network), which is should be faster than the outside connection, which, I would think, would mean that downloading something like an ISO or other large file from the Internet should be the same either way since that should saturate the connection anyway. Does it have something to do with the encryption (WPA)? Could it have something to do with MTU since the MTU for ethernet can be in the range of 1500 to 9000 bytes, and 2304 bytes for 802.11? Do wireless packets have to be buffered, whereas this wouldn't be an issue with ethernet? What's the math behind the difference?

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  • Limited connection whenever I connect to a Wi-Fi network outside the company

    - by anderZubi
    Whenever I connect my work laptop to a wireless network outside of my company, the connection shows as Limited, and there is no internet access. I have tried several times by disabling/enabling the network adapter, restarting the computer... without success. Sometimes, after a while, without taking any action, it shows fine, and I have internet access. But can pass 2 hours before this happens. My computer is under a domain network, but I don't think that's the problem, because I can successfuly connect other computers belonging to same domain to other networks. I'm running Windows 8 Pro and my network adapter is the following: Qualcomm Atheros AR9285 Wireless Network Adapter Any idea of which is the problem and how to solve it?

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  • Sendind an internet radio singal from my hifi to a portable

    - by Paul
    I'm just about to set myself up with a wireless network in my house. This is so that I can intregate an internet radio into my hifi system. What I would love to do is to listen to the radio in another room of the house. I also have a little portable radio/cd player that has a USB port on the front. Is there something I could buy which would allow me to listen to the radio through my portable in another room? I do realize that I could solve this problem by buying some wireless portable speakers, however I just wondered if anybody knew another way i.e. bluetooth or something similar?

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  • IP Address on internet access shared over ad-hoc wifi network

    - by Jacxel
    The Situation When im staying at my girlfriends we both like to have internet access on our laptops but her accommodation don't allow wireless routers. My Question My question is if I set up an Ad-Hoc network to share the internet connection as shown here on How To Geek. Will my laptop be acting as a wireless router or will the connection all go through my laptop as one ip address so it appears to be my computer accessing the webpages etc, that my girlfriend actually is. i would be interested in knowing any additional information that could help sove this problem eg. if connectify would do what i want.

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  • HP Officejet 6000 E609n unexpectedly goes offline

    - by Sajee
    My local library has a number of Windows Vista SP1 PCs connected to two HP Officejet 6000 E609n wireless printers. Each PC can print to either of the two printers and one of the two printers is the default on each PC. This configuration has worked well over the last year w/o any trouble. Recently, the library staff is reporting that sometimes when patrons try to print, they can't. Closer inspection shows that the the default wireless printer is offline. In order to get the printer online again, the printer has to be restarted. In Control Panel Printers applet, under the Printer menu, the "Use Printer Offline" option is grayed out and there's no way to bring the printer back online w/o restarting it. Does anyone know what's going on here?

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  • Need advice to choose correct wi-fi drivers for Dell Vostro 3560

    - by overdriven
    I'm having problems with my Dell notebook's Wi-Fi, it can't see some of the available access points, despite they are close and I used to be connected to them yesterday. Other notebooks and my phone can see them. I believe it's a driver issue, since after installing system I haven't downloaded any network drivers. I went to Dell's website to search for them but I have no idea which should I choose. For my Dell Vostro 3560 and system Windows 8.1 64bit these are available: Intel Smart Connect Technology Application APP_iSCT_W8.1_A00_Setup-TJW84_ZPE.exe (23 MB) Vostro-3560_Network_Application_TJW84_WN_4.2.40.2418_A00.EXE (29 MB) Dell Wireless 1704 WLAN 802.11b/g/n (2.4GHz), Bluetooth v4.0+HS Driver DW1704_W8.1_A00_Setup-K1HGN_ZPE.exe (239 MB) Network_Driver_K1HGN_WN_6.30.223.143_A00.EXE (247 MB) Dell Wireless1703 802.11 b/g/n, BT4.0 + HS Driver Dell Wireless1901 802.11a/b/g/n (2.4GHz and 5GHz), Bluetooth v4.0+HS Driver DW1703_DW1901_Win8.1_A00_Setup-7FPWR_ZPE.exe (265 MB) Network_Driver_7FPWR_WN_10.0.0.263_A00.EXE (272 MB) Realtek RTL8105E/RTL8111E Ethernet Controller Driver LOM_Realtek_W8.1_A00_Setup-0XCVW_ZPE.exe (6 MB) Network_Driver_0XCVW_WN_8.018.0621.2013_A00.EXE (12 MB) Intel® Centrino® Wireless-N 2230 Bluetooth Driver BT_Intel_W8.14_A00_Setup-XR83W_ZPE.exe (31 MB) Network_Application_XR83W_WN_3.1.1307.0362_A00.EXE (37 MB)

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  • DLINK Dir-655 Sharing and connecting wirelessly

    - by CYREX
    I have a D-LINK DIR-655 and i wish to do the following: My PC is connected to the internet via eth0 (Wired) and it has a wireless card. I wish to connect to the DIR-655 Router and share my connection via the router but wirelessly. I do not want to connect via a cabled wired to the router. I want to connect to the router via wifi. After that i want to make the Router share the wireless connection am giving it to other PCs wirelessly. So the sharing and connecting in all PCs will be done via WiFi.

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  • Windows file sharing connects over WiFi instead of LAN

    - by zacaj
    I have a laptop and a desktop computer, and I need to sync lots of files to the laptop and back whenever I go on a trip, etc. I've got a LAN cable connected into an extra port on the desktop that I plug into the laptop so I can get gigabit file transfers instead of wireless G. They connect fine. If I do an FTP transfer, for instance, using the LAN IP addresses, it goes at ~40MB/s, as it should. However when I copy files using explorer and native windows file sharing it detects the other computer by name, not IP (eg \\DESKTOP-PC\ instead of \\192.168.0.100\) and always connects to it by its wireless IP address instead of the faster LAN address. Both computers are running Windows 7. I have tried editing the priorities of the adapters in Advanced Settings and putting the LAN adapters above the wifi ones, but this didn't have any effect

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  • Windows 8.1 killed my wifi

    - by char1es
    Was running Windows 8 on a Lenovo G780 and updated to windows 8.1 Wifi does not work anymore, i always receive a dns server not responding error. I have tried using public dns servers from Google but with still no results. I've restarted my router with no results. All other devices on my network are having no trouble at all. I've tried updating the wireless driver but the manufacturers website claims that the Win8.1 driver should be updated with the update from windows. So i cant find a wireless driver... Anyone else having this error and does anyone have any ideas on how to fix it?? EDIT: here are the driver details: Broadcom 802.11n Network Adapter Provider: Microsoft Driver Date: 2013-05-31 Driver Version: 6.30.223.102 Digital Signer: Microsoft Windows Thanks

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  • Linux: Apple Wireless A1314 Fn key not registered, looks like software bug

    - by ramplank
    I'm trying to set up my Apple Wireless Keyboard with my Kubuntu systems. These are PC hardware powered by Intel Atom and Intel i5 respectively. The keyboard has a US keyboard layout and has model number A1314 written on the back. It takes two AA batteries. I'm saying that because it appears there are multiple types of model A1314. I have tried this on a 10.04, 11.04, 11.10 and 12.04 system with no success. Every time using a bluetooth dongle and the KDE bluetooth notification tray applet, the keyboard can be connected. In both cases it shows up as "Apple Wireless Keyboard". Almost everything works as expected, in fact, I'm typing on it right now. But one thing doesn't: The Fn key. I'd like to use Fn + Down Arrow as PgDn / Page Down, I understand this is default behaviour on Apple keyboards. And of course I'd like the same for Page Up, Home and End. I'll stick to Page Down in my example. I used the xev tool to see the keycodes the system receives, and if I press on Fn nothing happens, and nothing is registered. If I press Fn + Down Arrow, xev only registers the down arrow. Here's the output from my 11.04 system to illustrate: Press just the Fn key: no output Press Down Arrow key: KeyPress event, serial 36, synthetic NO, window 0x4400001, root 0x15d, subw 0x4400002, time 2699773, (44,45), root:(1352,298), state 0x10, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x4400001, root 0x15d, subw 0x4400002, time 2699860, (44,45), root:(1352,298), state 0x10, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False Press Fn+Down Arrow Keys together: KeyPress event, serial 36, synthetic NO, window 0x4400001, root 0x15d, subw 0x4400002, time 2701548, (44,45), root:(1352,298), state 0x10, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x4400001, root 0x15d, subw 0x4400002, time 2701623, (44,45), root:(1352,298), state 0x10, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False I've been searching this forum and other Linux-related forums for hours but I still have not found a solution. I mostly found advice on how to fix this when using an actual apple laptop or desktop, but I don't have that. They said to try something like the following echo 2 > /sys/module/hid_apple/ ... But since there's no hid_apple directory present on my systems, I've needed to modprobe hid_apple first. That didn't help either. I'm cool with changing some config files, or compiling my own patched kernel if that's necessary. I currently have a 10.04 and 12.04 system available to test. The same issue occurs when hooked up to Windows 7. Fn key still does nothing, not by itself or in combination with other keys. With some AutoHotkey fiddling, I was able to confirm the key is registered as pressed, but ignored by default. A custom AutoHotkey script can fix that. But AutoHotkey is only for Windows, I want my problem fixed on Linux. Hooked up to an iPad 2 it only works in combination with the F1-F12 keys. Not with the arrow keys. If the screen of the ipad is off, and I press just the Fn key, the screen will come on, so the key itself is registered as pressed. So to sum up my question: Can anyone help me get Page Up, Page Down, Home and End to work on this keyboard, when that requires me to use an Fn key which is currently not registered?

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  • Sharing internet connection with WDS

    - by cornjuliox
    Is it possible to share an internet connection through WDS? I'm on the very edge of a wireless network, the spot that I'm in maintains a stable 22% according to XP with the help of a parabolic reflector crafted from a cheap pie tin. I was thinking I could grab another wireless router, use WDS to bridge the this router with the other one and share the 'net connection through it thus giving me a little bit more freedom but when I tried it it didn't work. WDS looks like it bridged the networks just fine, but I couldn't access anything on the internet. Do I need to do anything special or is this just not possible?

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  • Cable installed - now my hub has no connection the router/modem - what do I need to buy?

    - by bcmcfc
    My previous setup was as follows: [modem/router]------[switch]+------ [pc1] +------ [pc2] I've just moved and had cable installed and I no longer have the option of running a lengthy LAN cable from the router to the switch to provide network and internet access to the two PCs. The cable company provided 2 wireless N USB adapters. What do I need to buy to plug into where in order to restore the network to its previous state? PC1 dual boots Windows 7 and Ubuntu 12. PC2 runs Debian 6. Edit: USB adapters - Netgear WNDA3200 Switch - TP-Link TL-SF1008D 8 port Ethernet switch Cabling - various patch cables cat5e rj45 Modem/Router - pretty standard cable company job - wireless Intention is something like- [modem/router] --wifi-- [some-new-hardware or perhaps to pc1] ----[switch]---[pc1/2]

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  • Need to know who is hogging my bandwidth?

    - by Dev
    I have an ethernet connection to my iMac and with Internet sharing I am broadcasting the wireless network from my mac rather than using a wireless router. I use it to connect other devices wirelessly to the internet. But this makes all the traffic flow through my iMac. I wanted a way to analyze the traffic so that I know what connected devices are hogging the bandwidth at a given time and from which websites? I installed wireshark for mac and played around a little but it seems like an overkill when you first look at it. Can someone please help with few instructions to get what I need or any other way other than using wireshark? Thanks Dev.

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  • Wifilink 5100 AGN mass update

    - by ripwads
    We are using a Meru enterprise wireless network with 180 APs. Recently, many users connections are dropping frequently. After much troubleshooting, we have determined much of the trouble is due to some settings in the advanced properties of the wireless nic on our notebooks. Now we want to send out the changes in a Zenworks bundle, but I cannot find these settings in the registry or anywhere we might be able to send out as a remote package. Does anyone know where to find these settings for an Intel wifilink 5100 card other that the NIC properties itself? We really do not want to manually configure 600 notebooks.

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  • Auto logon to internet provider

    - by user31673
    We use wireless internet access. The wireless is secured and to get an IP address, you provide the right key. That is setup just fine. However, on top of that, the first time we access the internet, a browser page appears and we have to enter a password. then we have access to the internet for a period of time. How can the password step be automated? I also have a web-based printer that doesn't work (except via USB connection) because it can't get out to the web. I can't change the router settings. Is there anything I can do to get the printer working and automatic the access?

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  • Slow performance with WAMP localhost access from other devices

    - by Adam
    I setup a localhost WAMP server and other device can access my localhost site on my win8 laptop with computer name instead of IP (bc I have use DCIP so that the wireless router can assign me IP otherwise it will not work). However, problem is that the website (WordPress), access speed is extremely slow on other devices other than my localhost computer, usually a 3s task take at least 10 seconds. (i.e. view my localhost site with computer name in a phone within the same wireless network.) Is that normal? What could be the reason causing it? Thank You

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  • Unauthorized computer use via keyboard or remote access?

    - by brydaverambo
    I’m suspecting my computer is being used when I’m not at home. This is happening either physically or remotely. My wireless switch is off. Is there any way possible to detect and/or monitor activity without purchasing software? My settings are being changed as well as passwords (Bios PW was changed and I cannot access Bios settings). I connect via the network cable. Is it possible for someone (in range) to connect to my laptop even if the wireless switch is off? This is a Dell Inspiron 1720 with the WLAN 1395 card. Here’s the kicker. When I try to download freeware for monitoring activity, I am not allowed to do this! ????

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  • Linux live cd with Broadcom Wi-fi support

    - by paul simmons
    I am looking for a live distro that has out of the box Broadcom wireless support. I am pretty happy with my Ubuntu installation and as long as I have an ethernet connection first time installed, I can install Broadcom drivers over internet. But being a little paranoid, I make my secure operations (banking etc.) with a live cd and zero hard disk access, so nothing is recorded. So far I plug ethernet to do such things with the live cd, but it would be nice if I can do same thing with wireless.

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  • D-Link router WiFi and LAN segment

    - by StreetStrider
    I have D-Link 2650 router. Some wireless and wired clients connected to it. The problem is there is no interconnection between wireless and wired devices. For instance, when I start webserver on PC connected to wired LAN, WiFi devices cannot access it (other wired devices can). However all devices are in the same subnet: 192.168.1.x. How can I connect WiFi and LAN devices to one network? Or maybe what I should know first (any information with which I can proceed)?

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  • I need a wirless interenet card thingy for my stationary computer

    - by user60859
    Going to move my stationary computer and hook it up to the TV. Which is far away from the wireless router. So i'm going to need a way to go on the Internet wirelessly from my stationary computer. I was looking at some of those.. wireless pci adapter things. But i have no idea which one would be compatible with my computer. How can i tell? oh i have a pentium 4, Windows XP like 600 megs of ram in case any of that matters.

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  • Intercepting LAN network traffic via WiFi

    - by user1613655
    Let's get straight to the point. This is my fictive network architecture: My question is: Would it be possible for Laptop B to intercept traffic sent and received by Laptop A? Please note that B only has WiFi access and no physical control over Router B. Furthermore, Router A and B create different wireless networks with different encryption keys. If both shared the same wireless network or Laptop B had LAN-access to Router B, the answer would be trivial, but I'm not sure how the answer turns out in this scenario :-/ Thanks for your valuable help!

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  • Wifi and eth behavior

    - by r00ster
    I have a wireless router 150M Wireless Lite N Router Model No. TL-WR740N / TL-WR740ND. Normally, when I'm connected to the local network using eth0 I can ping other machines by issuing ping name. When I'm connected through wifi I have to issue ping name.domain.com. The machine is only visible in intranet. How to achieve the same behavior with wifi? The second problem is, that I can not connect to some external sites through wifi but through eth everything is ok. I guess that is related to some port forwarding, but I'm not sure. How can I resolve this issue? EDIT: I'm using Linux Mint.

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  • Wifi network stopped being visible (and usable) (Linksys wag320n)

    - by s427
    Basically, my wifi network simply stopped working for no apparent reason. It doesn't appear in the list of the available networks anymore. I can see all my neighbors' networks, but not mine. It's as if it doesn't exist anymore. The internet connection (non-wifi), which goes through the same modem/router, is fine though. I already had a similar problem about one year ago (see here: Wifi network SSID not visible ), just after buying this very modem. I finally got it to work after performing two factory resets and getting rid of the Cisco "Magic" software; but this time it's not working. I use a linksys router-modem (WAG320N) which is directly connected (via network cable) to my desktop computer (Windows 7). I have (mainly) two devices that use the wifi network: my phone (Samsung Galaxy Nexus) and an Asus tablet (TF201, aka Transformer Prime). I also resurrected an old laptop computer (Dell, running Windows XP) to test that, and it doesn't see anything either (apart from the 20 other wifi networks, of course ^^). This wifi network was working just fine and has been for about a year. I haven't touched the modem settings so I have no idea what's causing the problem. I tried: making my phone "forget" about my network, hoping it would see it again after that: no luck. re-entering the network informations (SSID/password) manually on my phone: still no luck (says it's not in range) exporting the modem configuration, resetting the modem (factory reset, via modem admin), restarting it, importing the configuration: nope. factory reset, turning it off for 15 minutes, restarting, re-factory reset, and entering the configuration manually: still nothing. Has anybody experienced something similar before? Have you any suggestion to fix that? Thanks in advance. PS: to clear things up, here are the settings of my modem regarding wifi: Basic wireless settings: Configuration: manual Radio Band: 2.4GHz Wireless Network Mode: B/G/N-Mixed SSID: s427 Channel Bandwidth: Wide - 40 MHz Channel Wide Channel: 9 - 2.452GHz Standard Channel: 11 - 2.462GHz SSID Broadcast: Enable Advanced Wireless Settings AP Isolation: Disable Authentication Type: Auto Basic Rate: Default Transmission Rate: Auto N Transmission Rate: Auto CTS Protection Mode: Disable Beacon Interval: 100 DTIM Interval: 1 Fragmentation Threshold: 2346 RTS Threshold: 2346

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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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