Search Results

Search found 1703 results on 69 pages for 'intrusion detection'.

Page 46/69 | < Previous Page | 42 43 44 45 46 47 48 49 50 51 52 53  | Next Page >

  • ASP.net canvas server control

    - by Pierreten
    I was wondering if anyone has come up with an ASP.net server tag for the HTML5 canvas? I was thinking of something where I could declaritively define paths, curves; etc in the aspx markup, and the control would deliver the js to do this (perhaps with support for browser detection, and delivery of an emulation script for IE browsers.) Maybe a good idea for a Codeplex project for me to start up?

    Read the article

  • Detecting and handling third-party library filehandle leaks in Java

    - by tucuxi
    Is there any way to detect and handle whether a Java library is correctly releasing file-handles (via "close") from within a Java program that is using said library, short of having access to the actual library code and inserting the corresponding "finally close" statements? If detection is feasible, is there any way to close those file-handles without a reference to the Reader (or FileInputStream) that was reading the file?

    Read the article

  • How to use JavaScript to measure how bright a users monitor is ?

    - by HankV
    I've noticed that the brightness of computer monitors drastically varies between computers. As such, this changes the look of web pages greatly. Is there a way to use JavaScript to automatically detect how bright (or dark) a users monitor is so that I can adjust my web page colors accordingly? UPDATE Please note that I do not want manual user involvement. I want this detection to be automatic so that users don't realize I dynamically change the color palette automatically based on the brightness/darkness of their monitor.

    Read the article

  • PHP detecting filesystem encoding

    - by Evert
    Hi guys, I need to save files with non-latin filenames on a filesytem, using PHP. I want to make this work cross-platform. How do I know what encoding I can use to write the file? I understand many modern filesystems are UTF-8 based (is this correct?), but I doubt Windows XP is (for instance). So, is there a robust detection mechanism? Evert

    Read the article

  • Do USB interrupt transfers guarantee order?

    - by ulidtko
    I've found in the fairly awesome book titled "USB in a NutShell" that interrupt transfers provide reliable delivery (via error detection and automatic retry). But I wonder, does that guarantee that transfers will not be swapped in order someday? As far as the bus is serial, my guess is that yes, reordering should never occur. But I'm not really much into this, so having doubts. Could somebody clarify?

    Read the article

  • Image classification: recognizing various features of many buildings from images

    - by el chief
    so, let's say i have the long/lat or address of many buildings can get satellite images, "street view", and perhaps 3d/perspective views of buildings. want to find: height, number of floors, floor area (max building footprint) of the building. about 200k buildings. Is there a library for recognizing buildings from satellite shots or pictures? Kind of like face detection I suppose. Any other suggestions? Thanks!

    Read the article

  • Determining if two lines intersect

    - by Faken
    I have two lines that extend to infinity but both have a starting point. They are both described by a starting point and a vector in the direction of the line extending to infinity. I want to find out if the two lines intersect but i don't need to know where they intersect (its part of a collision detection algorithm). Everything i have looked at so far describes finding the intersection point of two lines or line segments. Anyone know a fast algorithm to solve this?

    Read the article

  • OpenCV haar training for static image

    - by Evl-ntnt
    I trying to train haar cascade classificator for card suite detection (which no rotation and has no distortion on image) For example I have file Clubs.png which contents clubs image on white background 20x20 pixels This tutorial is so tangled http://note.sonots.com/SciSoftware/haartraining.html My image varies only in sizes, no distortion or angling. Which commands I must enter in aim to get Clubs.xml file?

    Read the article

  • Nagios notifications definitions

    - by Colin
    I am trying to monitor a web server in such a way that I want to search for a particular string on a page via http. The command is defined in command.cfg as follows # 'check_http-mysite command definition' define command { command_name check_http-mysite command_line /usr/lib/nagios/plugins/check_http -H mysite.example.com -s "Some text" } # 'notify-host-by-sms' command definition define command { command_name notify-host-by-sms command_line /usr/bin/send_sms $CONTACTPAGER$ "Nagios - $NOTIFICATIONTYPE$ :Host$HOSTALIAS$ is $HOSTSTATE$ ($OUTPUT$)" } # 'notify-service-by-sms' command definition define command { command_name notify-service-by-sms command_line /usr/bin/send_sms $CONTACTPAGER$ "Nagios - $NOTIFICATIONTYPE$: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ ($OUTPUT$)" } Now if nagios doesn't find "Some text" on the home page mysite.example.com, nagios should notify a contact via sms through the Clickatell http API which I have a script for that that I have tested and found that it works fine. Whenever I change the command definition to search for a string which is not on the page, and restart nagios, I can see on the web interface that the string was not found. What I don't understand is why isn't the notification sent though I have defined the host, hostgroup, contact, contactgroup and service and so forth. What I'm I missing, these are my definitions, In my web access through the cgi I can see that I have notifications have been defined and enabled though I don't get both email and sms notifications during hard status changes. host.cfg define host { use generic-host host_name HAL alias IBM-1 address xxx.xxx.xxx.xxx check_command check_http-mysite } *hostgroups_nagios2.cfg* # my website define hostgroup{ hostgroup_name my-servers alias All My Servers members HAL } *contacts_nagios2.cfg* define contact { contact_name colin alias Colin Y service_notification_period 24x7 host_notification_period 24x7 service_notification_options w,u,c,r,f,s host_notification_options d,u,r,f,s service_notification_commands notify-service-by-email,notify-service-by-sms host_notification_commands notify-host-by-email,notify-host-by-sms email [email protected] pager +254xxxxxxxxx } define contactgroup{ contactgroup_name site_admin alias Site Administrator members colin } *services_nagios2.cfg* # check for particular string in page via http define service { hostgroup_name my-servers service_description STRING CHECK check_command check_http-mysite use generic-service notification_interval 0 ; set > 0 if you want to be renotified contacts colin contact_groups site_admin } Could someone please tell me where I'm going wrong. Here are the generic-host and generic-service definitions *generic-service_nagios2.cfg* # generic service template definition define service{ name generic-service ; The 'name' of this service template active_checks_enabled 1 ; Active service checks are enabled passive_checks_enabled 1 ; Passive service checks are enabled/accepted parallelize_check 1 ; Active service checks should be parallelized (disabling this can lead to major performance problems) obsess_over_service 1 ; We should obsess over this service (if necessary) check_freshness 0 ; Default is to NOT check service 'freshness' notifications_enabled 1 ; Service notifications are enabled event_handler_enabled 1 ; Service event handler is enabled flap_detection_enabled 1 ; Flap detection is enabled failure_prediction_enabled 1 ; Failure prediction is enabled process_perf_data 1 ; Process performance data retain_status_information 1 ; Retain status information across program restarts retain_nonstatus_information 1 ; Retain non-status information across program restarts notification_interval 0 ; Only send notifications on status change by default. is_volatile 0 check_period 24x7 normal_check_interval 5 retry_check_interval 1 max_check_attempts 4 notification_period 24x7 notification_options w,u,c,r contact_groups site_admin register 0 ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL SERVICE, JUST A TEMPLATE! } *generic-host_nagios2.cfg* define host{ name generic-host ; The name of this host template notifications_enabled 1 ; Host notifications are enabled event_handler_enabled 1 ; Host event handler is enabled flap_detection_enabled 1 ; Flap detection is enabled failure_prediction_enabled 1 ; Failure prediction is enabled process_perf_data 1 ; Process performance data retain_status_information 1 ; Retain status information across program restarts retain_nonstatus_information 1 ; Retain non-status information across program restarts max_check_attempts 10 notification_interval 0 notification_period 24x7 notification_options d,u,r contact_groups site_admin register 1 ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE! }

    Read the article

  • Load Testing a Security/Gateway Appliance

    - by Joel Coel
    In a couple weeks I will load testing a security/gateway appliance. We're a small residential college, and that "residential" means the traffic moving through the appliance is a bit like the Wild West. We have everything from Facebook to World of Warcraft, BitTorrent to Netflix, or Halo to YouTube... basically anything you might find in the home of a high-school or college aged person. Somewhere in there some real academic work gets done as well. We rely on our current appliance for traffic shaping, antivirus, malware filtering, intrusion detection on our servers, logging and abuse reporting, and even some content filtering. All this puts a decent load when we have students around, and I'm concerned about the ability of the new candidate to keep up. On paper it should handle things, but I'm worried. Prior experience is that vendors greatly over-report what an appliance can handle. The product also includes a licensed session limit, and I'm also worried that just a few misbehaving students could unwittingly bring us to that limit and cause service disruptions. I need to know this will work for our campus in order to commit to it. Going a performance level higher in that product takes the pricing way out of line with what we expect and have done in the past. What I need is a good way to load test this guy. My problem is that our current level of summer traffic is less than one percent of what it will be when students come back just six weeks from now. Any ideas on how to really stress this thing and see what it can do, in a way that will give me some clear ideas o. How that will scale for our campus? For the curious, I'm looking at a Watchguard 515, but it could be anything. If I were evaluating a competitor, I'd ask the same question.

    Read the article

  • ipmi - can't ping or remotely connect

    - by Fidel
    I've tried configuring the IPMI controller to accept remote connections, but I can't even ping it. Here is it status: #/usr/local/bin/ipmitool lan print 2 Set in Progress : Set Complete Auth Type Support : NONE PASSWORD Auth Type Enable : Callback : : User : NONE PASSWORD : Operator : PASSWORD : Admin : PASSWORD : OEM : IP Address Source : Static Address IP Address : 192.168.1.112 Subnet Mask : 255.255.255.0 MAC Address : 00:a0:a5:67:45:25 IP Header : TTL=0x40 Flags=0x40 Precedence=0x00 TOS=0x10 BMC ARP Control : ARP Responses Enabled, Gratuitous ARP Enabled Gratituous ARP Intrvl : 8.0 seconds Default Gateway IP : 192.168.1.1 Default Gateway MAC : 00:00:00:00:00:00 802.1q VLAN ID : Disabled 802.1q VLAN Priority : 0 RMCP+ Cipher Suites : 0,1,2,3 Cipher Suite Priv Max : uaaaXXXXXXXXXXX : X=Cipher Suite Unused : c=CALLBACK : u=USER : o=OPERATOR : a=ADMIN : O=OEM # /usr/local/bin/ipmitool user list 2 ID Name Enabled Callin Link Auth IPMI Msg Channel Priv Limit 1 true false true true USER 2 admin true false true true ADMINISTRATOR # /usr/local/bin/ipmitool channel getaccess 2 2 Maximum User IDs : 5 Enabled User IDs : 2 User ID : 2 User Name : admin Fixed Name : No Access Available : callback Link Authentication : enabled IPMI Messaging : enabled Privilege Level : ADMINISTRATOR # /usr/local/bin/ipmitool channel info 2 Channel 0x2 info: Channel Medium Type : 802.3 LAN Channel Protocol Type : IPMB-1.0 Session Support : multi-session Active Session Count : 0 Protocol Vendor ID : 7154 Volatile(active) Settings Alerting : disabled Per-message Auth : disabled User Level Auth : disabled Access Mode : always available Non-Volatile Settings Alerting : disabled Per-message Auth : disabled User Level Auth : disabled Access Mode : always available # /usr/local/bin/ipmitool chassis status System Power : on Power Overload : false Power Interlock : inactive Main Power Fault : false Power Control Fault : false Power Restore Policy : unknown Last Power Event : Chassis Intrusion : inactive Front-Panel Lockout : inactive Drive Fault : false Cooling/Fan Fault : false # arp Address HWtype HWaddress Flags Mask Iface 192.168.1.112 ether 00:A0:A5:67:45:25 C bond0 # /usr/local/bin/ipmitool -I lan -H 192.168.1.112 -U admin -P admin chassis power status Error: Unable to establish LAN session Unable to get Chassis Power Status In summary. It exists on the ARP list so arp's are being broadcast. I can't ping it and can't connect to it. Can anyone spot any glaring mistakes in the configuration? Many thanks, Fidel

    Read the article

  • Linux: prevent outgoing TCP flood

    - by Willem
    I run several hundred webservers behind loadbalancers, hosting many different sites with a plethora of applications (of which I have no control). About once every month, one of the sites gets hacked and a flood script is uploaded to attack some bank or political institution. In the past, these were always UDP floods which were effectively resolved by blocking outgoing UDP traffic on the individual webserver. Yesterday they started flooding a large US bank from our servers using many TCP connections to port 80. As these type of connections are perfectly valid for our applications, just blocking them is not an acceptable solution. I am considering the following alternatives. Which one would you recommend? Have you implemented these, and how? Limit on the webserver (iptables) outgoing TCP packets with source port != 80 Same but with queueing (tc) Rate limit outgoing traffic per user per server. Quite an administrative burden, as there are potentially 1000's of different users per application server. Maybe this: how can I limit per user bandwidth? Anything else? Naturally, I'm also looking into ways to minimize the chance of hackers getting into one of our hosted sites, but as that mechanism will never be 100% waterproof, I want to severely limit the impact of an intrusion. Cheers!

    Read the article

  • What Logs / Process Stats to monitor on a Ubuntu FTP server?

    - by Adam Salkin
    I am administering a server with Ubuntu Server which is running pureFTP. So far all is well, but I would like to know what I should be monitoring so that I can spot any potential stability and security issues. I'm not looking for sophisticated software, more an idea of what logs and process statistics are most useful for checking on the health of the system. I'm thinking that I can look at various parameters output from the "ps" command and compare to see if I have things like memory leaks. But I would like to know what experienced admins do. Also, how do I do a disk check so that when I reboot, I don't get a message saying something like "disk not checked for x days, forcing check" which delays the reboot? I assume there is command that I can run as a cron job late at night. How often should it be run? What things should I be looking at to spot intrusion attempts? The only shell access is SSH on a non-standard port through UFW firewall, and I regularly do a grep on auth.log for "Fail" or "Invalid". Is there anything else I should look at? I was logging the firewall (UFW) but I have very few open ports (FTP and SSH on a non standard port) so looking at lists of IP's that have been blocked did not seem useful. Many thanks

    Read the article

  • Using GPO to collect data about VMware view activity

    - by MoSiAc
    Our security group wants us to begin logging data for external access to our view enviroment. At first we thought that view security would be logging all source ip's that are external in nature so if for some reason there is an intrusion we would have record of it there. Of course our firewall logs all that information but correlating it to view is sketchy at best with our current implementation. We know on viewdesktops there is a set of keys in VolitateEnviroment that contains stuff such as source ip and username, etc. We have a script in place that, when run as a logon script attached to a user account in AD collects the information as we need it. If we have a GPO run the same script the information does not get collected. We feel like there is a piece of the puzzle we're missing but we don't know what. If anyone knows what we're forgetting or misconfiguring that would be great, or if you have a better way of us collecting external source ip's for view specifically we'd be interested in that as well. Thanks, EDIT CODE Batch script to dump to text file @echo off timeout 20 echo %computername%/%username% %time% %date% c:\vdi\vmware.txt echo ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~c:\vdi\vmware.txt reg query "HKEY_CURRENT_USER\Volatile Environment" /v "ViewClient_LoggedOn_Username"c:\vdi\vmware.txt reg query "HKEY_CURRENT_USER\Volatile Environment" /v "ViewClient_IP_Address"c:\vdi\vmware.txt echo.c:\vdi\vmware.txt VB Script to display values Const HKEY_CURRENT_USER = &H80000001 Set wmiLocator=CreateObject("WbemScripting.SWbemLocator") Set wmiNameSpace = wmiLocator.ConnectServer(".", "root\default") Set objRegistry = wmiNameSpace.Get("StdRegProv") sPath = "Volatile Environment" lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_Machine_Name", vMachine) lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_IP_Address", vIP) lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_MAC_Address", vMAC) msgbox "The Remote Device Name is " & vMachine & " @ " & vIP & " (" & vMAC & ") " he wanted me to mention that the batch file actually runs and I can see it counting down when I reconnect but it does not grab the registry values.

    Read the article

  • What Logs / Process Stats to monitor on a Ubuntu FTP server?

    - by Adam Salkin
    I am administering a server with Ubuntu Server which is running pureFTP. So far all is well, but I would like to know what I should be monitoring so that I can spot any potential stability and security issues. I'm not looking for sophisticated software, more an idea of what logs and process statistics are most useful for checking on the health of the system. I'm thinking that I can look at various parameters output from the "ps" command and compare to see if I have things like memory leaks. But I would like to know what experienced admins do. Also, how do I do a disk check so that when I reboot, I don't get a message saying something like "disk not checked for x days, forcing check" which delays the reboot? I assume there is command that I can run as a cron job late at night. How often should it be run? What things should I be looking at to spot intrusion attempts? The only shell access is SSH on a non-standard port through UFW firewall, and I regularly do a grep on auth.log for "Fail" or "Invalid". Is there anything else I should look at? I was logging the firewall (UFW) but I have very few open ports (FTP and SSH on a non standard port) so looking at lists of IP's that have been blocked did not seem useful. Many thanks

    Read the article

  • Thank You for a Great Welcome for Oracle GoldenGate 11g Release 2

    - by Irem Radzik
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; 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-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Yesterday morning we had two launch webcasts for Oracle GoldenGate 11g Release 2. I had the pleasure to present, as well as moderate the Q&A panels in both of these webcasts. Both events had hundreds of live attendees, sending us over 150 questions. Even though we left 30 minutes for Q&A, it was not nearly enough time to address for all the insightful questions our audience sent. Our product management team and I really appreciate the interaction we had yesterday and we are starting to respond back with outstanding questions today. Oracle GoldenGate’s new release launch also had great welcome from the media. You can find the links for various articles on the new release below: ITBusinessEdge Oracle Embraces Cross-Platform Data Integration Information Week: Oracle Real-Time Advance Taps Compressed Data Integration Developer News, Oracle GoldenGate Adds Deeper Oracle Integration, Extends Real-Time Performance CIO, Oracle GoldenGate Buddies Up with Sibling Software DBTA, Real-Time Data Integration: Oracle GoldenGate 11g Release 2 Now Available CBR Oracle unveils GoldenGate 11g Release 2 real-time data integration application In this blog, I want to address some of the frequently asked questions that came up during the webcasts. You can find the top questions and their answers along with related resources below. We will continue to address frequently asked questions via future blogs. Q: Will the new Integrated Capture for Oracle Database replace the Classic Capture? If not, which one do I use when? A: No, Classic Capture will be around for long time. Core platform specific features, bug fixes, and patches will be available for both Capture processes.Oracle Database specific features will be only available in the Integrated Capture. The Integrated Capture for Oracle Database is an option for users that need to capture data from compressed tables or need support for XML data types, XA on RAC. Users who don’t leverage these features should continue to use our Classic Capture. For more information on Oracle GoldenGate 11g Release 2 I recommend to check out the White paper: Oracle GoldenGate 11gR2 New Features as well as other technical white papers we have on OTN.                                                         For those of you coming to OpenWorld, please attend the related session: Extracting Data in Oracle GoldenGate Integrated Capture Mode, Monday Oct 1st 1:45pm Moscone South – 102 to learn more about this new feature. Q: What is new in Conflict Detection and Resolution? And how does it work? A: There are now pre-built functions to identify the conditions under which an error occurs and how to handle the record when the condition occurs. Error conditions handled include inserts into a target table where the row already exists, updates or deletes to target table rows that exist, but the original source data (before columns) do not match the existing data in the target row, and updates or deletes where the row does not exist in the target database table.Foreach of these conditions a method to handle the error is specified.  Please check out our recent blog on this topic and the White paper: Oracle GoldenGate 11gR2 New Features white paper.  Also, for those attending OpenWorld please attend the session: Best Practices for Conflict Detection and Resolution in Oracle GoldenGate for Active/Active-  Wednesday Oct 3rd  3:30pm Mascone 3000 Q: Does Oracle GoldenGate Veridata and the Management Pack require additional licenses, or is it incorporated with the GoldenGate license? A: Oracle GoldenGate Veridata and Oracle Management Pack for Oracle GoldenGate are additional products and require separate licenses. Please check out Oracle's price list here. Q: Does GoldenGate - Oracle Enterprise Manager Plug-in require additional license? A: Oracle Enterprise Manager Plug-in is included in the Oracle Management Pack for Oracle GoldenGate license, which is separate from Oracle GoldenGate license. There is no separate license for the Enterprise Manager Plug-in by itself. Oracle GoldenGate Monitor, Oracle GoldenGate Director, and Enterprise Manager Plug-in are included in the Management Pack for Oracle GoldenGate license. Please check out Management Pack for Oracle GoldenGate data sheet for more info on this product bundle. Q: Is Oracle GoldenGate replacing Oracle Streams product? A: Oracle GoldenGate is the strategic data replication product. Therefore, Oracle Streams will continue to be supported, but will not be actively enhanced. Rather, the best elements of Oracle Streams will be added to Oracle GoldenGate. Conflict management is one of them and with the latest release Oracle GoldenGate has a more advanced conflict management offering. Current customers depending on Oracle Streams will continue to be fully supported. Q: How is Oracle GoldenGate different than Oracle Data Integrator? A: Oracle Data Integrator is designed for fast bulk data movement and transformation between heterogeneous systems, while GoldenGate is designed for real-time movement of transactions between heterogeneous systems. These two products are completely complementary where GoldenGate provides low-impact real-time change data capture and delivery to a staging area on the target. And Oracle Data Integrator transforms this data and loads the DW tables. In fact, Oracle Data Integrator integrates with GoldenGate to use GoldenGate’s Capture process as one option for its CDC mechanism. We have several customers that deployed GoldenGate and ODI together to feed real-time data to their data warehousing solutions. Please also check out Oracle Data Integrator Changed Data Capture with Oracle GoldenGate Data Sheet (PDF). Thank you again very much for welcoming Oracle GoldenGate 11g Release 2 and stay in touch with us for more exciting news, updates, and events.

    Read the article

  • Movement prediction for non-shooters

    - by ShadowChaser
    I'm working on an isometric 2D game with moderate-scale multiplayer, approximately 20-30 players connected at once to a persistent server. I've had some difficulty getting a good movement prediction implementation in place. Physics/Movement The game doesn't have a true physics implementation, but uses the basic principles to implement movement. Rather than continually polling input, state changes (ie/ mouse down/up/move events) are used to change the state of the character entity the player is controlling. The player's direction (ie/ north-east) is combined with a constant speed and turned into a true 3D vector - the entity's velocity. In the main game loop, "Update" is called before "Draw". The update logic triggers a "physics update task" that tracks all entities with a non-zero velocity uses very basic integration to change the entities position. For example: entity.Position += entity.Velocity.Scale(ElapsedTime.Seconds) (where "Seconds" is a floating point value, but the same approach would work for millisecond integer values). The key point is that no interpolation is used for movement - the rudimentary physics engine has no concept of a "previous state" or "current state", only a position and velocity. State Change and Update Packets When the velocity of the character entity the player is controlling changes, a "move avatar" packet is sent to the server containing the entity's action type (stand, walk, run), direction (north-east), and current position. This is different from how 3D first person games work. In a 3D game the velocity (direction) can change frame to frame as the player moves around. Sending every state change would effectively transmit a packet per frame, which would be too expensive. Instead, 3D games seem to ignore state changes and send "state update" packets on a fixed interval - say, every 80-150ms. Since speed and direction updates occur much less frequently in my game, I can get away with sending every state change. Although all of the physics simulations occur at the same speed and are deterministic, latency is still an issue. For that reason, I send out routine position update packets (similar to a 3D game) but much less frequently - right now every 250ms, but I suspect with good prediction I can easily boost it towards 500ms. The biggest problem is that I've now deviated from the norm - all other documentation, guides, and samples online send routine updates and interpolate between the two states. It seems incompatible with my architecture, and I need to come up with a better movement prediction algorithm that is closer to a (very basic) "networked physics" architecture. The server then receives the packet and determines the players speed from it's movement type based on a script (Is the player able to run? Get the player's running speed). Once it has the speed, it combines it with the direction to get a vector - the entity's velocity. Some cheat detection and basic validation occurs, and the entity on the server side is updated with the current velocity, direction, and position. Basic throttling is also performed to prevent players from flooding the server with movement requests. After updating its own entity, the server broadcasts an "avatar position update" packet to all other players within range. The position update packet is used to update the client side physics simulations (world state) of the remote clients and perform prediction and lag compensation. Prediction and Lag Compensation As mentioned above, clients are authoritative for their own position. Except in cases of cheating or anomalies, the client's avatar will never be repositioned by the server. No extrapolation ("move now and correct later") is required for the client's avatar - what the player sees is correct. However, some sort of extrapolation or interpolation is required for all remote entities that are moving. Some sort of prediction and/or lag-compensation is clearly required within the client's local simulation / physics engine. Problems I've been struggling with various algorithms, and have a number of questions and problems: Should I be extrapolating, interpolating, or both? My "gut feeling" is that I should be using pure extrapolation based on velocity. State change is received by the client, client computes a "predicted" velocity that compensates for lag, and the regular physics system does the rest. However, it feels at odds to all other sample code and articles - they all seem to store a number of states and perform interpolation without a physics engine. When a packet arrives, I've tried interpolating the packet's position with the packet's velocity over a fixed time period (say, 200ms). I then take the difference between the interpolated position and the current "error" position to compute a new vector and place that on the entity instead of the velocity that was sent. However, the assumption is that another packet will arrive in that time interval, and it's incredibly difficult to "guess" when the next packet will arrive - especially since they don't all arrive on fixed intervals (ie/ state changes as well). Is the concept fundamentally flawed, or is it correct but needs some fixes / adjustments? What happens when a remote player stops? I can immediately stop the entity, but it will be positioned in the "wrong" spot until it moves again. If I estimate a vector or try to interpolate, I have an issue because I don't store the previous state - the physics engine has no way to say "you need to stop after you reach position X". It simply understands a velocity, nothing more complex. I'm reluctant to add the "packet movement state" information to the entities or physics engine, since it violates basic design principles and bleeds network code across the rest of the game engine. What should happen when entities collide? There are three scenarios - the controlling player collides locally, two entities collide on the server during a position update, or a remote entity update collides on the local client. In all cases I'm uncertain how to handle the collision - aside from cheating, both states are "correct" but at different time periods. In the case of a remote entity it doesn't make sense to draw it walking through a wall, so I perform collision detection on the local client and cause it to "stop". Based on point #2 above, I might compute a "corrected vector" that continually tries to move the entity "through the wall" which will never succeed - the remote avatar is stuck there until the error gets too high and it "snaps" into position. How do games work around this?

    Read the article

< Previous Page | 42 43 44 45 46 47 48 49 50 51 52 53  | Next Page >