Search Results

Search found 30252 results on 1211 pages for 'network programming'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 394/1211 | < Previous Page | 390 391 392 393 394 395 396 397 398 399 400 401  | Next Page >

  • Interview question ranking FizzBuzz (1), implementing malloc (10)

    - by blrs
    I'd like to have your opinion on the difficulty of the following interview question: Find the subarray with maximum sum in an array of integers in O(n) time. This trivial sounding problem was made famous by Jon Bentley in his Programming Pearls where he uses it to demonstrate algorithm design techniques. On a scale of 1-10, 1 being the FizzBuzz (or HoppityHop) test and 10 being implement the C stdlib function malloc(), how would you rank the above problem? I think the people who can best answer this question are those who have read Programming Pearls and have tried to solve this problem on their own. To motivate those who haven't, 'Programming Pearls' gets featured many times in the 'Top 10 programming books' list.

    Read the article

  • Can I use the Airport Express as a an uplink between two networks?

    - by Ant Swift
    I have two separate networks using different IP ranges, 192.168.0.* for the wired only, isolated network and 192.160.1.* for the wireless only network which is connected to the internet. The wired network has a network printer setup and working and I want to be able to share it out to members of the wireless network (see diagram below). In short I need some kind of uplink between the two networks. Currently running a cable is out since there is no suitable route. I have a spare Airport Express and I am wondering if I could attach it to the wired network and have it join the wireless and act as the uplink between the two. Anyone know if the device is capable of this?

    Read the article

  • How do I prevent TCP connection freezes over an OpenVPN network?

    - by Jason R
    New details added at the end of this question; it's possible that I'm zeroing in on the cause. I have a UDP OpenVPN-based VPN set up in tap mode (I need tap because I need the VPN to pass multicast packets, which doesn't seem to be possible with tun networks) with a handful of clients across the Internet. I've been experiencing frequent TCP connection freezes over the VPN. That is, I will establish a TCP connection (e.g. an SSH connection, but other protocols have similar issues), and at some point during the session, it seems that traffic will cease being transmitted over that TCP session. This seems to be related to points at which large data transfers occur, such as if I execute an ls command in an SSH session, or if I cat a long log file. Some Google searches turn up a number of answers like this previous one on Server Fault, indicating that the likely culprit is an MTU issue: that during periods of high traffic, the VPN is trying to send packets that get dropped somewhere in the pipes between the VPN endpoints. The above-linked answer suggests using the following OpenVPN configuration settings to mitigate the problem: fragment 1400 mssfix This should limit the MTU used on the VPN to 1400 bytes and fix the TCP maximum segment size to prevent the generation of any packets larger than that. This seems to mitigate the problem a bit, but I still frequently see the freezes. I've tried a number of sizes as arguments to the fragment directive: 1200, 1000, 576, all with similar results. I can't think of any strange network topology between the two ends that could trigger such a problem: the VPN server is running on a pfSense machine connected directly to the Internet, and my client is also connected directly to the Internet at another location. One other strange piece of the puzzle: if I run the tracepath utility, then that seems to band-aid the problem. A sample run looks like: [~]$ tracepath -n 192.168.100.91 1: 192.168.100.90 0.039ms pmtu 1500 1: 192.168.100.91 40.823ms reached 1: 192.168.100.91 19.846ms reached Resume: pmtu 1500 hops 1 back 64 The above run is between two clients on the VPN: I initiated the trace from 192.168.100.90 to the destination of 192.168.100.91. Both clients were configured with fragment 1200; mssfix; in an attempt to limit the MTU used on the link. The above results would seem to suggest that tracepath was able to detect a path MTU of 1500 bytes between the two clients. I would assume that it would be somewhat smaller due to the fragmentation settings specified in the OpenVPN configuration. I found that result somewhat strange. Even stranger, however: if I have a TCP connection in the stalled state (e.g. an SSH session with a directory listing that froze in the middle), then executing the tracepath command shown above causes the connection to start up again! I can't figure out any reasonable explanation for why this would be the case, but I feel like this might be pointing toward a solution to ultimately eradicate the problem. Does anyone have any recommendations for other things to try? Edit: I've come back and looked at this a bit further, and have found only more confounding information: I set the OpenVPN connection to fragment at 1400 bytes, as shown above. Then, I connected to the VPN from across the Internet and used Wireshark to look at the UDP packets that were sent to the VPN server while the stall occurred. None were greater than the specified 1400 byte count, so the fragmentation seems to be functioning properly. To verify that even a 1400-byte MTU would be sufficient, I pinged the VPN server using the following (Linux) command: ping <host> -s 1450 -M do This (I believe) sends a 1450-byte packet with fragmentation disabled (I at least verified that it didn't work if I set it to an obviously-too-large value like 1600 bytes). These seem to work just fine; I get replies back from the host with no issue. So, maybe this isn't an MTU issue at all. I'm just confused as to what else it might be! Edit 2: The rabbit hole just keeps getting deeper: I've now isolated the problem a bit more. It seems to be related to the exact OS that the VPN client uses. I have successfully duplicated the problem on at least three Ubuntu machines (versions 12.04 through 13.04). I can reliably duplicate an SSH connection freeze within a minute or so by just cat-ing a large log file. However, if I do the same test using a CentOS 6 machine as a client, then I don't see the problem! I've tested using the exact same OpenVPN client version as I was using on the Ubuntu machines. I can cat log files for hours without seeing the connection freeze. This seems to provide some insight as to the ultimate cause, but I'm just not sure what that insight is. I have examined the traffic over the VPN using Wireshark. I'm not a TCP expert, so I'm not sure what to make of the gory details, but the gist is that at some point, a UDP packet gets dropped due to the limited bandwidth of the Internet link, causing TCP retransmissions inside the VPN tunnel. On the CentOS client, these retransmissions occur properly and things move on happily. At some point with the Ubuntu clients, though, the remote end starts retransmitting the same TCP segment over and over (with the transmit delay increasing between each retransmission). The client sends what looks like a valid TCP ACK to each retransmission, but the remote end still continues to transmit the same TCP segment periodically. This extends ad infinitum and the connection stalls. My question here would be: Does anyone have any recommendations for how to troubleshoot and/or determine the root cause of the TCP issue? It's as if the remote end isn't accepting the ACK messages sent by the VPN client. One common difference between the CentOS node and the various Ubuntu releases is that Ubuntu has a much more recent Linux kernel version (from 3.2 in Ubuntu 12.04 to 3.8 in 13.04). A pointer to some new kernel bug maybe? I'm assuming that if that were so, then I wouldn't be the only one experiencing the problem; I don't think this seems like a particularly exotic setup.

    Read the article

  • configuring linux server to send traffic to local machines using local IP address

    - by gkdsp
    Two linux servers, server1 and server2, are on the same local network (they also have access to an external network). Server2 has a local IP of 192.168.0.2 and a host name of host2.mydomain.com. QUESTION 1: If an application on server1 sends traffic to server2 using a host name of host2.mydomain.com, what determines whether this traffic is routed to server2 using the local or external network? QUESTION 2: To ensure that all traffic sent from server1 to server2 always uses the local network, could I simply include in the server1 /etc/hosts file the following? 192.168.0.2 host2.mydomain.com ...the thinking being, if the servers are always on the same network there should never be a need for server2 to send traffic to server1 via the external network (that I can think of anyway). Is this done in practice, or is some other method preferred?

    Read the article

  • Wireless keeps disabling or stays disconnected (Realtek RTL8191SEvB)

    - by jindrichm
    I have Realtek RTL8191SEvB wireless card on Ubuntu 10.10: $ lspci -v | grep Network 03:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8191SEvB Wireless LAN Controller (rev 10) When I load its driver, according to the Network Manager it sometimes blinks with a list of available networks but it keeps disabling itself or it stays disconnected. So, I can't connect to any wi-fi network (which results in frustration). The driver is loaded: $ lsmod Module Size Used by r8192se_pci 509932 0 Looks normal: $ sudo lshw -C network *-network description: Wireless interface product: RTL8191SEvB Wireless LAN Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 10 serial: 1c:65:9d:60:c7:7a width: 32 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=rtl819xSE driverversion=0019.1207.2010 firmware=63 latency=0 link=no multicast=yes wireless=802.11bgn resources: irq:17 ioport:2000(size=256) memory:f0500000-f0503fff Configured: $ sudo iwconfig wlan0 wlan0 802.11bgn Nickname:"rtl8191SEVA2" Mode:Managed Frequency=2.412 GHz Access Point: Not-Associated Bit Rate:130 Mb/s Retry:on RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=10/100 Signal level=0 dBm Noise level=-100 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 Is not blocked: $ rfkill list all 0: tpacpi_bluetooth_sw: Bluetooth Soft blocked: no Hard blocked: yes However something's happening with it: $ dmesg [ 6485.948668] InitializeAdapter8190(): ==++==> Turn off RF for RfOffReason(1073741824) ---------- [ 6486.062666] rtl8192_SetWirelessMode(), wireless_mode:10, bEnableHT = 1 [ 6486.062671] InitializeAdapter8192SE(): Set MRC settings on as default!! [ 6486.062675] HW_VAR_MRC: Turn on 1T1R MRC! [ 6486.064091] ADDRCONF(NETDEV_UP): wlan0: link is not ready [ 6486.248761] rtl8192_SetWirelessMode(), wireless_mode:10, bEnableHT = 1 [ 6486.248771] InitializeAdapter8192SE(): Set MRC settings on as default!! [ 6486.248776] HW_VAR_MRC: Turn on 1T1R MRC! [ 6486.580083] GPIOChangeRF - HW Radio OFF [ 6486.610085] ============>sync_scan_hurryup out [ 6486.623814] ================>r8192_wx_set_scan(): hwradio off [ 6486.830484] =========>r8192_wx_set_essid():hw radio off,or Rf state is eRfOff, return So, does anyone know where the problem might be?

    Read the article

  • How to connect to my own WiFi using Broadcom STA drivers?

    - by Chris
    I'm trying hard to switch to Linux from Windows because of my engineering project. Unfortunately, everything is against that change! Before I have installed Broadcom STA proprietary drivers, I was seeing on NetworkManager and nm-applet only local radio-internet-access networks. After I installed Broadcom STA, I see my neighbor's wireless network (channel 11, WEP) Neither before nor after the installation is own wireless network available. Computer: Asus Lamborghini VX6 Ubuntu: 12.04 LTS 64-bit Router: ASUS N55U (A1) with newest AsusWRT firmware Network: Channel 5 (tried also 10 and 11, both on 20 and 40MHz bands), WPA2 Personal, 2,4 + 5 GHz (what is not very important, 'cause the wlan card in VX6 is only 2,4GHz). Network works fine on Windows, also through D-Link repeater on the other floor. Unfortunately, same network is invisible to Ubuntu on same machine. I have tried some combinations with other GUIs but it did not work. Are there any better drivers for Ubuntu? I need that network badly, but I'm an Ubuntu newbie, so I don't know how to solve that problem. Please help.

    Read the article

  • How do I make the correct career decision in regards to product manager/QA vs programmer?

    - by Adel
    I'm curious about how to approach the issue of whether I should focus on programming or on QA/testing/product management. I know that the latter seems like a broad category( if so, think of it as "general IT support" for now). At the moment I'm stronger in QA/prod. mgt ; however I'd like to switch more to programming, and I see I may have this opportunity. Wouldn't it be easier to switch to QA/prod. mgt in the future, if I go into programming now; rather than trying the reverse-order(i.e. if I decided later to go into coding.. say around mid-30s then it'd likely be harder). Just looking for any advice or tips about how to see more clearly. Part of me is scared I can't handle the programming side, but part of me says since there's demand and I'm interested that it's still worth a shot.

    Read the article

  • I still can't figure out how to program!

    - by Mark K.
    Please help! I've read lots of programming books for various languages, Java, Python, C, etc. I understand and know all of the basics of the languages and I understand algorithms and data structures. (Equivilant of say 2 years of CompSci classes) BUT, I still can't figure how to write a program that does anything useful. All of the programming books show you how to write the language, but NOT how to use it! The programming examples are all very basic like build a card catalog for a library or a simple game or use algorithms etc... They dont't show you how to develop complex programs that actually do anything useful! I've looked a open-source programs on sourceforge, but they don't make much sense to me. There are hundreds of files in each program & thousands of lines of code. But how do I learn how to do this? There's nothing in any book I can buy on Amazon that will give me the tools to write any of these programs. How do you go from reading Intro to Java or Programming Python, or C Programming Language, etc.. to actually being able to say, I have an idea for X Program.. this is how I go about developing it? It seems like there is so much more involved in writing a program than you can learn in a book or from a class. I feel like there is someth Can anyone put me on the right track?

    Read the article

  • Wifi won't connect to certain networks

    - by Dave M G
    As I write this, I'm in a coffee shop on my laptop, and I am trying to connect to the free wifi network they offer. Every time I select their network from the wifi applet drop down menu, it connects for a second and then disconnects. At the same time, I have my Android phone with me, and it connects to the coffee shop's network without problem. There are a couple of people around me also using the same network with no issues. I asked the staff to check and as far as they can tell there is no problem with their router or anything. I have tried rebooting, but it has not made a difference. I have double and triple checked that I am using the correct WEP password. As an added wrinkle, when I connect to another network, it seems to connect (although I can't use them because they are paid gateway services). So I'm able to ask this question now because I have tethered my laptop to my phone, but it's slow and a workaround, not a solution. All indications are that it's a problem with my computer against this one network. Why would that be and how can I fix it?

    Read the article

  • Allowing users in from an IP address without certificate client authentication

    - by John
    I need to allow access to my site without SSL certificates from my office network and with SSL certificates outside. Here is my configuration: <Directory /srv/www> AllowOverride All Order deny,allow Deny from all # office network static IP Allow from xxx.xxx.xxx.xxx SSLVerifyClient require SSLOptions +FakeBasicAuth AuthName "My secure area" AuthType Basic AuthUserFile /etc/httpd/ssl/index Require valid-user Satisfy Any </Directory> When I'm inside network and have certificate - I can access. When I'm inside network and haven't certificate - I can't access, it requires certificate. When I'm outside network and have certificate - I can't access, it shows me basic login screen When I'm outside network and haven't certificate - I can't access, it shows me basic login screen and following configuration works perfectly <Directory /srv/www> AllowOverride All Order deny,allow Deny from all Allow from xxx.xxx.xxx.xxx AuthUserFile /srv/www/htpasswd AuthName "Restricted Access" AuthType Basic Require valid-user Satisfy Any </Directory>

    Read the article

  • IIS App Pool Identity Internet Settings

    - by Programming Hero
    How does an IIS App Pool determine its Internet Settings? I'm specifying a custom identity under which to host a .NET web application, a service account that is part of our Active Directory domain. When the application runs, it needs to make HTTP requests to other servers. This action causes it to read web and proxy settings from some location, but I can't understand where it goes for this information. Does it look: At the default account's settings on that box? At the default profile on the AD server? Its own local/roaming profile? A combination of the above? Somewhere completely different?

    Read the article

  • what should I read in Windows [closed]

    - by Umesha MS
    I think I am asking generic question. Being a developer in windows what should I read to improve my skills? Do I need to read concepts on need basis or do I need to read concepts well in advance? If I want to read the concepts in advance then what topics do I need to read. (Note : I am a Windows developer. I use c++ programming language, Win32/MFC frame work and I use Visual studio IDE.) Updated: To be more specific when a fresher comes to my team I will ask him to read the following things and I tell him that these are very important. 1)C++ : 1 The C++ Programming Language by Bjarne Stroustrup's 2 Thinking in C++ 2nd Edition by Bruce Eckel 2)Win32/MFC : 1 Programming Applications for Microsoft Windows by Jeffrey Richter 2 windows programming by charles petzold 3 Programming Windows with MFC –by Jeff Prosise For 2 years and above developer I ask them to read 1)Above concepts (C++ and Win32/MFC)are mandate 2)Design Pattern : 1)Gang Of Four. 2)Head first patter. 3)Design princples. But for above 6 years’ experience developer what are the concepts are important.

    Read the article

  • Two domains accessing same folder

    - by Liam Quinn
    I've just taken a new role in a school and am still familiarizing myself with their network, how ever I have recently been given a task and I'm having a little trouble finding out the fundementals of it. I have an admin network/domain 10.49.x.x and a classroom network/domian 192.168.1.x both connect to a Proxy server 10.49.202.231/192.168.1.51. Each domain has it's own shared folders as you'd expect, files and software installs etc, how ever there is a folder "staff" on the classroom network that all the teachers on the classroom network can access. The users on the admin network would like to access this same folder. How do I go about making this happen?

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 390 391 392 393 394 395 396 397 398 399 400 401  | Next Page >