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  • Is it a good Idea to switch to a SSD to use less battery?

    - by Walter Maier-Murdnelch
    I am thinking of buying a SSD for my laptop, mainly for the purpose of extended operating time when running on battery. At the moment I use a Hitachi HTS545032B9A300 (320GB) (Datasheet) as main drive and a Seagate Momentus 5400.3 120GB as secondary drive. I dualboot Windows and Linux but I don't need the windows partition any longer, a 120GB SDD would be more than sufficient space-wise. Speed is not an issue for me, I make heavy use of tmpfs (ramdrive) within Linux and transfers of bigger files are mainly through some network filesystem anyways, thus a cheaper SSD should do. For the purpose of comparison I chose the OCZ Vertex Plus 120GB. Power consumption always is a big promotional thing the industry uses to make me want to buy their SSDs, some sheet on the OCZ page provides an astonishing comparison of desktop HDDS and SSDs. The numbers I got comparing my laptop HDD and their SSD were not really astonishing any longer. Hitachi 320GB HDD: Startup (W, peak, max.) 4.5 Seek (W, avg.) 1.7 Read / Write (W, avg.) 1.4 Performance idle (W, avg.) 1.3 Active idle (W, avg.) 0.8 Low power idle (W, avg.) 0.5 Standby (W, avg.) 0.2 Sleep 0.1 OCZ 120GB SSD: 1.5W active 0.3W standby I see that there are differences, but actually they don't seem that high as I though they were. And compared to the power consuption of the rest of my system I wonder if it makes a difference at all. Have I just taken the wrong look at the whole thing or may I be better off to buy another battery for my laptop?

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  • Apache suddenly very slow on http and faster on https

    - by hsnm
    Background: I have Apache 2 running on ubuntu. There is a low usage on it and mostly being accessed for a web service URL from mobile apps. It was working fine until I installed SSL certificates. I now have both http and https. When I access the server using https, I get a fairly quick response (but probably not as fast as before). When I use http, it's so slow. What I tried: From this post: I curl localhost from the host and it takes some time, meaning there is no routing issue. The server runs on Amazon EC2 instance and is managed by me only. Also: I see that Apache once running, creates the maximum number of processes it is allowed to, which was not the case before. I lowered the MaxClients to 20 and I think I'm getting faster responses but it still takes over a minute and I always have MaxClients Apache processes. dmesg returns many [ 1953.655703] TCP: Possible SYN flooding on port 80. Sending cookies. When I netstat I get many entries with SYN_RECV. Possibly a DDoS attack? From EC2's monitoring diagrams I see a pattern of high "Maximum Network In (Bytes)" since 2 days ago. By the way the server is still being tested, the actual traffic is very low and not consistent. I tried to go with this solution to limit incoming connections using iptables, still no luck, but I'm trying. Question: What could be the problem? Is this a DDoS attack?

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  • Windows 7 Taskbar resets on every login

    - by Arne Mertz
    I like to reorder my Taskbar a bit, other than the Windows 7 default is. I use two "rows", the lower is for quicklaunch and other toolbars: This works perfectly, as long as I don't log off from the computer. Every time I log in, Windows 7 has messed up/reset the toolbar positions like this: So I have to drag them into position again and again, every morning. Fixing the taskbar positions won't help, I tried to google for the problem but it does not seem to be very common. Does anyone recognize that problem and has a solution? Update: This is not the AutoLogon bug. AutoLogon is off. We have installed Novell at our company, and it does not matter wether I log directly onto the Novell network or only to the computer first and to Novell later. Update2: I get the same issue when I logon without Novell, i.e. when I log on only to the computer. When I boot in safe mode, the taskbar looks essentially the same: Update3: KB979155 says it's "not applicable to my system". Creating a neew user is not an option since I don't have the admin privileges to do that - I have almost any other local admin privileges, though.

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  • Ubuntu - wireless connection works great but wired is totally dead

    - by Dan
    I am running Ubuntu 10.04 on my Acer Aspire One netbook. The wireless connection works great, but the wired is totally dead. When I plug the Ethernet wire, the little led next to the port doesn't blink. If I do ifconfig, this is the output: lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:1659 errors:0 dropped:0 overruns:0 frame:0 TX packets:1659 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:132304 (132.3 KB) TX bytes:132304 (132.3 KB) wlan0 Link encap:Ethernet HWaddr 18:f4:6a:65:48:1f inet addr:192.168.1.7 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::1af4:6aff:fe65:481f/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:94823 errors:0 dropped:0 overruns:0 frame:0 TX packets:81390 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:93028474 (93.0 MB) TX bytes:18002558 (18.0 MB) There is no eth0. Is that normal? In the "Network Connections" GUI there is an entry "Wired connection 1", its "MAC address" field is blank. How can I make the wired connection work?

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  • ADSL2+ - High sync-rate, good line attenuation, but low noise margin and slow speeds

    - by Mark Pim
    I've been with my ISP (IdNet) for a few months and have been getting some good speeds, but in the last week the speed has dramatically decreased (from 15 Mbps+ to around 0.2 Mbps). This happens at all times of day, not just peak periods. Obviously I've done all I can to isolate problems my end - only one PC is connected to the router (via ethernet cable) and no other background programs are using the network etc. I've raised the issue with the ISP and they've suggested trying a new ADSL filter to see if that is casuing the problem, but I thought it would also be good to get the opinion of superuser on possible causes or other troubleshooting I can do. Here are the juicy stats :) My router (Netgear DGN1000) reports: Downstream Upstream Connection Speed 17602 kbps 1062 kbps Line Attenuation 17.9 db 8.6 db Noise Margin 6.0 db 6.1 db I used RouterStats and it seems to show those figures stay fairly consistent all the time I ran the BT speedtest and it reported: download speed of 164 kbps, out of a max achievable of 21000 kbps upload speed of 859 kbps, out of 1048 kbps DSL connection rate 17719 kbps down and 1048 kbps up IP Profile of 15000 kbps Is there any more troubleshooting I can do? Does this look like a problem with my equipment / wiring or with BT's line? Any advice would be great :)

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  • Blocking of certain file downloads

    - by Philip Fourie
    I have a problem where I cannot completely download a certain file from a server. The file is 1.9MB in size but only 68% is downloaded and then it hangs. I tried and these cases, which failed: Downloaded the file with HTTP Downloaded the file with FTP Moved the file to different FTP and web servers behind the ISA firewall Tried with IIS 6.0 & IIS 7.0 Multiple download clients. Which included FireFox, FileZilla (on Windows) and wget (on Linux) This worked: Downloading other files from the same location on the server. Both bigger and smaller and in size than the original. FTP and HTTP worked. Earlier version of this file (.DLL) works. It is as if the content of this file has an influence on this file being served. Network architecture: Client Machine - Internet (ISP) - ISA Server - IIS 7.0 The only constants are the ISP, Cisco router and the ISA server. Is it possible that something is rejecting the download because of the contents of the file? I am hoping ISA is the culprit... I am not a ISA expert is there somewhere I can look to establish if it is indeed ISA causing this? Update: Splitting the file into two parts with a hex editor results in one half of the file being served correctly and the other part not. Zipping the file results in the file being downloaded successfully. However this is not an option for this particular scenario. Renaming the file and its extension also doesn't work. Update 2009/10/22: It does NOT seems to be ISA that is causing this problem. We connected a laptop (running IIS) on an available public IP and still the file download to 68% before it hanged. The two remaining components are the ISP and the Cisco 800 series router. Anyone knows about an issue on the router perhaps?

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  • Server-side SSH jump hosts

    - by Dan Sosedoff
    Trying to figure out server side SSH jump hosts logic. Current network schema: [Client] <--> [Server A: hostname: a.com] <--> [Server B] [Client] <--> [Server A: hostname: b.com] <--> [Server C] Server A responds to both DNS records. Possible flow: Client opens a ssh connection with ssh [email protected]. Server A accepts it and should automatically jump user onto Server B with ssh user2@server_b.com. Client opens a ssh connection with ssh [email protected]. Server A accepts it and should automatically just user onto Server C with ssh user2@server_c.com. In other words, client should be able to connect to the target without performing any local configuration, assuming that we have a stock ssh config. The problem with ssh jumps is that user has to define hosts in local ~/.ssh/config file, which is not acceptable in my case. It needs to be a default sshd behavior. Im aware that you can define a custom command ~/.ssh/authorized_keys on server, but i dont think there is a way to properly detect source hostname where user tries to connect. It is possible at all ?

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  • Connecting a Wifi router to receivers with a cable instead of antenna?

    - by 31eee384
    This is a very strange question--I'd go so far as to say it's a stupid question. I'm being told that it is possible to, to describe it briefly, use a cable to connect an access point and a receiver directly to one another. This means that I would unscrew the access point's antenna, and attach one end of a cable to the port. Then, on the wireless receiver, I would also unscrew the antenna and plug in the other side of the cable. I'm being told the connection would work after this, just as a normal Wifi connection would. Bonus mini-question: if this works, would it still work if a splitter were attached to the access point and multiple receivers plugged in to the network? What would happen if I do this? Based on my surprisingly deficient knowledge of radio transmission, I don't think it would work. I would like some help knowing why it won't (or will) though, if possible. This is a somewhat hypothetical question--I realize that Ethernet does this exact job very handily, and I could just throw in a switch instead of the splitter. I simply feel that I should understand this scenario. Thanks for any help you can offer.

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  • IIS 7 much slower than IIS 6

    - by JoeJoe
    I have a asp.net 3.5 web application running fine on Windows2003 IIS6. I published same exact application to IIS7.5 (Win2008R2) on a faster box (i5,8Gram) and it is significantly slower. 5-6 sec per page vs. 1-2 sec per page. During that time the Task Mgr CPU is always under 10%. Both attach to same database on other box. Benchmark is consistent from any other client browser or machine. I have connection pool on both, compression on both. Same network subnet. Forms authentication (no SSL yet). Can you give me steps on how to troubleshoot where the delays are being inserted or settings in IIS7 that I may have overlooked. Just using defaults. There is only 1 web site on each box. I understand the roles of an Application as defined in IIS has changed. There is no special Application defined in IIS.

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  • How to set a static route for an external IP address

    - by HorusKol
    Further to my earlier question about bridging different subnets - I now need to route requests for one particular IP address differently to all other traffic. I have the following routing in my iptables on our router: # Allow established connections, and those !not! coming from the public interface # eth0 = public interface # eth1 = private interface #1 (10.1.1.0/24) # eth2 = private interface #2 (129.2.2.0/25) iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -m state --state NEW ! -i eth0 -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i eth0 -o eth2 -m state --state ESTABLISHED,RELATED -j ACCEPT # Allow outgoing connections from the private interfaces iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT # Allow the two private connections to talk to each other iptables -A FORWARD -i eth1 -o eth2 -j ACCEPT iptables -A FORWARD -i eth2 -o eth1 -j ACCEPT # Masquerade (NAT) iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # Don't forward any other traffic from the public to the private iptables -A FORWARD -i eth0 -o eth1 -j REJECT iptables -A FORWARD -i eth0 -o eth2 -j REJECT This configuration means that users will be forwarded through a modem/router with a public address - this is all well and good for most purposes, and in the main it doesn't matter that all computers are hidden behind the one public IP. However, some users need to be able to access a proxy at 192.111.222.111:8080 - and the proxy needs to identify this traffic as coming through a gateway at 129.2.2.126 - it won't respond otherwise. I tried adding a static route on our local gateway with: route add -host 192.111.222.111 gw 129.2.2.126 dev eth2 I can successfully ping 192.111.222.111 from the router. When I trace the route, it lists the 129.2.2.126 gateway, but I just get * on each of the following hops (I think this makes sense since this is just a web-proxy and requires authentication). When I try to ping this address from a host on the 129.2.2.0/25 network it fails. Should I do this in the iptables chain instead? How would I configure this routing?

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  • Same native and tagged vlan possible on Redhat?

    - by Chris Phillips
    Hi guys and gals, I'm looking at implementing a systems using a number of tagged and a native vlan connected to a server over a a/p bonded interface. The untagged vlan is for physical machine access, the tagged vlans are connected to bridges and then to QEMU VM's inside the machine. Hopefully this plan is fine, but I'm trying to implement a crippled version of this in a dev environment due to a lack of underlying network config in this location where I just have the same single vlan delivered to the machine on a tag AND plain. I'm nto clear if this is going to work (and that I should just be confident that it will work using different vlans) as I'm seeing odd things like a vm is arping out over the vlan out to the core switch, but the arp reply is coming back on the untagged interface. Now an ARP reply is unicast right? So it's a deliberate thing to send the ARP response on the untagged interface, and not a case that a broadcast response isn't being passed on the tagged side... i.e. there's some underlying logic pushing it that way. Something about the MACs somehow? This is on a CentOS 5.5 machine, vlan's from vconfig. (I've seen reference to the Linux mac-vlan project work, but that's not available here by default.) so 1) Should having the SAME vlan tagged and untagged work? 2) Will different tagged vlans to the untagged interface work nice and easily?

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  • Can't ping localhost/or reach locally hosted domain

    - by Ian
    I can't reach a locally hosted domain, and in testing I have discovered I can't ping localhost or the actual IP either. OS is Windows7 64bit, Pro. DNS works, I can ping others on my network, they can ping me, and they can reach the hosted domain. The ONLY problem I have found is that I can't reach the locally hosted domains! C:\Users\ianipconfig /all Windows IP Configuration Host Name . . . . . . . . . . . . : leda Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : hcs Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : hcs Description . . . . . . . . . . . : Atheros AR8121/AR8113/AR8114 PCI-E Ethern et Controller Physical Address. . . . . . . . . : 00-23-54-7C-E2-2A DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes IPv4 Address. . . . . . . . . . . : 192.168.0.12(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.0.1 DNS Servers . . . . . . . . . . . : 192.168.0.1 NetBIOS over Tcpip. . . . . . . . : Enabled Ethernet adapter VirtualBox Host-Only Network #2: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : VirtualBox Host-Only Ethernet Adapter #2 Physical Address. . . . . . . . . : 08-00-27-00-88-4A DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Autoconfiguration IPv4 Address. . : 169.254.205.215(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : NetBIOS over Tcpip. . . . . . . . : Enabled C:\Users\ianping localhost Pinging leda [127.0.0.1] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 127.0.0.1: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), C:\Users\ianping coachmaster.leda.hcs Pinging coachmaster.leda.hcs [192.168.0.12] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 192.168.0.12: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), C:\Users\ian I can reach a hosted VM in VirtualBox and the VM can browse the hosted sites. I've removed Zone Alarm and disabled Windows Firewall - same results. So how can I browse my locally hosted sited? What could be blocking it? Thanks Ian

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  • RESOLVED Why does IPtables's NAT stop working when I enable the firewall's third interface?

    - by Kronick
    On my firewall I've three interfaces : eth0 : public IP (46.X.X.X.) eth0:0 public IP (46.X.X.Y.) eth1 : public IP (88.X.X.X.) eth2 : private LAN (172.X.X.X) I've setup a basic NAT which works great until I turn on the eth1 interface, I basically loose the connectivity. When I turn off the interface (ifconfig eth1 down) then the NAT re-work. I've added some policy routing via iproute, which makes my three public IP's available. I don't understand why turning on eth1 on makes the LAN unavailable. PS : weirder ; when I turn on eth1 BUT remove the NAT, then the firewall is accessible by using the public IPS. So to me it's exclusively a NAT issue, since without the NAT the network works while with the NAT without the second public interface, the NAT does work. Regards EDIT : I've been able to make it work by using iproute2 rules. That was definitely a routing issue. Here is what I did : ip rule add prio 50 table main ip rule add prio 201 from ip1/netmask table 201 ip rule add prio 202 from ip2/netmask table 202 ip route add default via gateway1 dev interface1 src ip1 proto static table 201 ip route append prohibit default table 201 metric 1 proto static ip route add default via gateway2 dev interface2 src ip2 proto static table 202 ip route append prohibit default table 202 metric 1 proto static # mutipath ip rule add prio 221 table 221 ip route add default table 221 proto static \ nexthop via gateway1 dev interface1 weight 2\ nexthop via gateway2 dev interface2 weight 3

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  • Trying to delete a directory stored on a Windows server, from on a Mac, containing files created on the Mac, getting "Directory not empty"

    - by AdamG
    I am trying to delete a directory stored on a Windows 2008 R2 server, mounted on a Mac as network home (10.8.5). The directory was created by Safari and stores temporary internet files. I need to be able to delete this folder on logout from a Mac bash script. The Terminal on Mac shows the directory as empty: 36W-FacRm-02:History lwickham$ cd /home/lwickham/Library/Caches/Metadata/Safari/History 36W-FacRm-02:History lwickham$ ls -al total 0 drwx------ 1 lwickham CGPS\Domain Users 264 Nov 8 09:24 . drwx------ 1 lwickham CGPS\Domain Users 264 Nov 8 09:28 .. However, on the Windows server it has a single 0kb file that doesn't start with a "." but yet is invisible to the Mac. E:\FacultyHome2\lwickham\Library\Caches\Metadata\Safari\History>dir Volume in drive E is FacultyUsers2 Volume Serial Number is 8C17-4EF3 Directory of E:\FacultyHome2\lwickham\Library\Caches\Metadata\Safari\History 11/08/2013 09:24 AM <DIR> . 11/08/2013 09:24 AM <DIR> .. 11/07/2013 04:28 PM 0 http?%2F%2Fwww.google.com%2Furl?sa=t&rct= j&q=&esrc=s&source=web&cd=6&ved=0CFsQFjAF&url=http%253A%252F%252Fwww.usbanklocat ions.com%252Fhsbc-bank-usa-96th-street-branch.html&ei=5vR7UtmXEPjfsATe0YCIBA&usg =AFQjCNF9ypKbpYbXRng00FY3W8Y6cF1Tiw&bvm=bv.56146854,d. 1 File(s) 0 bytes 2 Dir(s) 514,231,967,744 bytes free 9ypKbpYbXRng00FY3W8Y6cF1Tiw&bvm=bv.56146854,d.1 File(s) 0 bytes2 Dir(s) 514,231,967,744 bytes free All my attempts to delete the dir from the Mac have failed: 36W-FacRm-02:History lwickham$ rm -fr /home/lwickham/Library/Caches/Metadata/Safari/History/* 36W-FacRm-02:History lwickham$ rm -frd /home/lwickham/Library/Caches/ rm: /home/lwickham/Library/Caches//Metadata/Safari/History: Directory not empty rm: /home/lwickham/Library/Caches//Metadata/Safari: Directory not empty rm: /home/lwickham/Library/Caches//Metadata: Directory not empty rm: /home/lwickham/Library/Caches/: Directory not empty

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  • Cisco configuration for public library internet

    - by AlternateZ
    I'm a C/C++ computer programmer turned IT support guy working for a public library. My day is usually spent helping random grandparents learn how to use email, so my networking knowledge is limited to what I can glean from google. Here's the situation. We have a public library with 20 PCs on a LAN and also public wifi access. Previously we were running all of this on 1 ADSL connection and people complained about low speeds. We hired a networking company to set up a Cisco dual-WAN router for us, and purchased an additional ADSL connection. The intention was to give the LAN PCs a guaranteed amount of bandwidth each, and then let the wifi users split the rest. The results were far worse than what we expected, and all we got from the company was excuses and they've since washed their hands of us. During busy periods, net performance on the LAN PCs are so poor that attaching files to gmail etc often times out and fails - far from the "guaranteed amount of bandwidth each" that we hope for! Sometimes it feels like performance is worse than before when we had 1 ADSL link and an unconfigured router? Anyways, surely this is a problem encountered a million times over across the world? (Sharing internet across many users effectively.) What are standard solutions for something like this? I admit to not even knowing the right jargon to google for (load balancing?) I'd appreciate any links to resources/guides that might help me get a better understanding of the problem/solutions, and perhaps some stories of your own experience in solving similar problems. This will help us evaluate and negotiate with network consultants in the future. If its relevant, our router config contains a section "policy-map" with "bandwidth percent" for each class of user (LAN, wifi), and "fair queue".

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  • What can prevent a Server 2008 machine accessing its OWN UNC shares?

    - by Simon
    I need to set up a UNC share for my hosted dedicated server to access a share on itself. Unfortunately TFS requires a UNC share. I am on a Windows Server 2008 Standard SP2 64bit dedicated server behind a PIX 501 firewall hosted with GoDaddy. I just cannot get the server to access itself and get this error: Windows cannot access \\SERVER\SHARE Check the spelling of the name.. etc. I've found numerous questions about this but no answer to my problem. Server 2008 Standard x64 SP2 Workgroup - not domain Windows Firewall is off Computer browser service is on I am trying to access \\MYMACHINE\TFS-BUILDS by typing in - or double clicking. Neither works. Machine has single network card Filesharing wizard says share was ok Share was showing under 'Computer management' Permissions are set to 'everyone' full control No obvious errors in eventlog Reboot didn't fix it Unfortunately I cannot try to access other shares in or out of this machine because it is a hosted dedicated server and the only machine behind a hardware firewall. The only thing left i can think of is that the hardware firewall needs to be configured. I don't think it is this because we have a 2003 Server machine behind a different hardware firewall and that one works fine. What on earth is left?!

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  • Consulting: Organizing site/environment documentation for customers?

    - by ewwhite
    Over time, I've taken on consulting and contract engineering work for various clients. More recently, customers are asking for certain types of documentation. These are small businesses and typically do not have dedicated technical staff. Within a single company, Wiki/Confluence/Sharepoint, etc. all make sense as a central repository for documentation and environment information. I struggle with finding a consistent method to deliver the following information to discrete customers. I'm shooting for a process that's more portable, secure and elegant than a simple spreadsheet or the dreaded binder full of outdated information. Important IP addresses, DHCP scope, etc. Network diagram (if needed). Administrative usernames and passwords and management URLs. Software license keys. Support contracts and warranty information. Vendor support contacts and instructions. I know there are other consultants here. Any suggestions or tips on maintaining documentation across multiple environments in a customer-friendly format? How do you do it?

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  • Deploying multiple identical copies of a virtual machine for compute tasks

    - by Reid
    I have a compute task which has a large number of library dependencies. I would like to deploy it on some of my company's large Linux clusters, where I do not have root. I could probably track down, compile, and install the right versions of all the libraries, but this looks to be quite tedious and would have to be repeated if I deployed it again somewhere else. On the other hand, it's pretty easy to install on current Ubuntu. This led me to wonder about a virtual machine approach. Could I put together a virtual machine which booted up, ran the computation (with parameters from and results to the host), and then shut down? In other words, I'd like a command like this that I could run on the host: $ ./run-vm --ram N --task /path/on/host/foo.sh --results /another/host/dir/ This would boot the VM, run foo.sh, and put the (relatively small) results of the computation in /another/host/dir/. It's important to start up many instances of the VM simultaneously, both on a single node and multiple nodes of the cluster. So it would be nice if I didn't have to make many copies of the VM virtual disk and metadata. As the task instances are completely independent, the VMs would not need any network support once deployed, or any outside communications beyond reading and writing the host filesystem. Is this possible, and if so, how might I go about doing it? Are there assumptions I've made above which are bogus?

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  • Is this a good starting point for iptables in Linux?

    - by sbrattla
    Hi, I'm new to iptables, and i've been trying to put together a firewall which purpose is to protect a web server. The below rules are the ones i've put together so far, and i would like to hear if the rules makes sense - and wether i've left out anything essential? In addition to port 80, i also need to have port 3306 (mysql) and 22 (ssh) open for external connections. Any feedback is highly appreciated! #!/bin/sh # Clear all existing rules. iptables -F # ACCEPT connections for loopback network connection, 127.0.0.1. iptables -A INPUT -i lo -j ACCEPT # ALLOW established traffic iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # DROP packets that are NEW but does not have the SYN but set. iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP # DROP fragmented packets, as there is no way to tell the source and destination ports of such a packet. iptables -A INPUT -f -j DROP # DROP packets with all tcp flags set (XMAS packets). iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP # DROP packets with no tcp flags set (NULL packets). iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP # ALLOW ssh traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport ssh -m limit --limit 1/s -j ACCEPT # ALLOW http traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport http -m limit --limit 5/s -j ACCEPT # ALLOW mysql traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport mysql -m limit --limit 25/s -j ACCEPT # DROP any other traffic. iptables -A INPUT -j DROP

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  • Can't remote into Virtual PC

    - by Spamela
    I used to be able to remote into my Virtual PCs. It has been working for at least a year. Yesterday just stopped working... I cannot figure it out... Things I have triple-checked: 1. My Virtual PCs have "Allow Remote Access" checked. 2. My Virtual PCs have an account in the Administrator group that is password protected. 3. My Host's entry in the registry for the Terminal Services Port is still the default of 3389. So here is the strange thing. I can't even remote into the Virtual PC from it's host much less another PC... From the host, I can ping the Virtual PC and get a response but when trying to remote into it from the host I get the following error: Remote Desktop can't connect to the remote computer for one of these reasons: 1)Remote access to the server is not enabled. 2)The remote computer is turned off 3)The remote computer is not available on the network My host is running Windows 7. Virtual PCs are running XP. Thank you for looking at this!

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  • Primary/secondary ethernet interfaces in Ubuntu 9.10

    - by Josh
    I have an Ubuntu 9.10 machine with three ethernet interfaces, eth0, eth1 and eth2. eth2 is connected to a private network. eth0 and eth2 are connected to two different LANs. Either one will provide access to the internet. All three networks have DHCP servers. Using Ubuntu's the default settings (And Gnome), when I boot up all the interfaces are active and my system gets three IP addresses. However any attempt to access the internet results in connection timeouts and other weirdness. I suspect that traffic is going out on one NIC (like eth0) and coming back in on another (like eth1). I'm not sure what's going on. The only way I can access the internet at the moment is to bring two of the devices down with ifdown. How can I configure eth0 as my primary interface so all trafic goes out by default on that interface, while keeping the other two active? Also, I want to make sure Avahi broadcasts properly on all three IPs so that the computers on the LAN of eth1 can still connect to myHostname.local...

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  • What hardware would I need (approx) to run ESXi server?

    - by mr.b
    Hi, I am considering to purchase off-the-shelf commodity hardware in order to build server that will host virtual machines using ESXi server. Intended purpose for this server is NOT mission critical tasks. It will have to run perhaps 20-50 Windows XP/Vista/7 virtual machines (in total, but closer to 20 figure). Each guest would have to have 1-2 GB of ram, and probably two-three times more disk space than guest OS needs with clean install and all updates applied (that would be around 6-8 GB for XP, and i believe closer to 10-15 for win7). Those guests will act as a test ground for a new product that is network management software, thus guests will idle most of their time once initially loaded, but if I give them some task to complete, they should be able to perform reasonably well. Now, from what I have learned... CPU is usually not much of an issue (6 cores would do it), memory should not be lacking, but doesn't have to be sum of all guests, because of overcommitment... That leads me to IO, which is, as it seems, the bottleneck. Since I have very little experience with ESXi (and ESX, too) server, I'd like to ask: How much memory could I save by overcommitment, and how does it affect performance? Is 6-core cpu enough to run above described system? Would it be possible to run entire server off two (or even one) SSD drives (to host system virtual disks, with few additional HDDs (2-3) in RAID 0 to be used as secondary storage? I read somewhere that ESXi allows having something like "master image", essentially virtual machine that is "deployed" many times, so that disk space can be saved by having only differences stored by specific guests, instead of copying around whole virtual disks. Is this true, and how can this help me? Are there any other things I need to take into consideration when building this off-the-shelf solution? I should probably mention here that I'm fully aware of issues like SPOF regarding power supply, raid 0, etc, but since it's only a testing ground and not a production system, it's not so important for me. Thanks, B.

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  • Restoring a fresh home folder in a shared user domain environment

    - by Cocoabean
    I am using a tool called pGINA that adds another credential provider to my Windows 7 clients so we can authenticate campus users via campus LDAP. We have the default Windows credential providers setup to authenticate off of our Active Directory, but we have students in our classes that don't have entries in our AD, and we need to know who they are to allow them internet access. Once these LDAP users login using pGINA, they are all redirected to the same AD account, a 'kiosk' account with GPOs in place to prevent anything malicious. My concern is that my users will accidentally save personal login information or files in that shared profile, and another user may login later and have access to a previous user's Gmail account, as the AppData folder on each computer is shared by anyone logging into the kiosk user. I've looked into MS's 'roll-your-own' SteadyState but it didn't seem to have what I wanted. I tried to write a PS script to copy a pre-saved clean version of the profile from a network share, but I just kept running into issues with CredSSP delegation and accessing the share from the UNC path. Others have recommended something like DeepFreeze but I'd like to do it without 3rd party tools if possible.

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  • SSH connection times out unless I tunnel in from a different server-

    - by rm-vanda
    OK, so this just started last week - Whenever we try to connect to our server via ssh (we use sftp, as well) - The connection times out. However, when you ssh to any other server and then ssh into the machine - it works flawlessly. Now, the mindblowing thing is that sometimes the ssh connection will succeed. Moments ago, I tried it from another machine, and then my own, and it worked - only to time out the next go around. Last week, simply restarting the ssh daemon worked, but this week, no such luck. I even went in and changed: /etc/hosts.allow ALL : ALL and /etc/hosts.deny is blank. The firewall config hasn't changed - but I even disabled the firewall to see if that would work - It did, for a moment - before cutting off, again. (ufw is set to "ALLOW" not "LIMIT") When I try SSH'ing in from my phone -- it works, fine -- So, it seems the problem is with our ISP/router/gateway - However, I see no log in the router/gateway that says its blocking our connections - And that wouldn't explain why we can SSH into any other server -- except for this one - from our network --- I truly appreciate any insight that anyone may have on this matter -

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  • 100% uptime for a web application

    - by Chris Lively
    We received an interesting "requirement" from a client today. They want 100% uptime with off-site failover on a web application. From our web application's viewpoint, this isn't an issue. It was designed to be able to scale out across multiple database servers, etc. However, from a networking issue I just can't seem to figure out how to make it work. In a nutshell, the application will live on servers within the client's network. It is accessed by both internal and external people. They want us to maintain an off-site copy of the system that in the event of a serious failure at their premises would immediately pick up and take over. Now we know there is absolutely no way to resolve it for internal people (carrier pigeon?), but they want the external users to not even notice. Quite frankly, I haven't the foggiest idea of how this might be possible. It seems that if they lose Internet connectivity then we would have to do a DNS change to forward traffic to the external machines... Which, of course, takes time. Ideas? UPDATE I had a discussion with the client today and they clarified on the issue. They stuck by the 100% number, saying the application should stay active even in the event of a flood. However, that requirement only kicks in if we host it for them. They said they would handle the uptime requirement if the application lives entirely on their servers. You can guess my response.

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