how can identify client computer uniquely for website users

Cookies

Set a cookie on the client machine to identify the user.

  • Pros: Definitely unique per session
  • Cons: Easy to remove or prevent (even for people with limited technical knowledge), only apply to one browser, easy for a script to bypass

IP address

Use the user’s IP address to identify the user.

  • Pros: Changes infrequently, works across browsers, requires technical knowledge to spoof or use a proxy server
  • Cons: Not necessarily unique: one IP address can easily apply to entire homes/buildings/offices behind a network, and for some ISPs end user IP addresses might be reassigned

Browser fingerprinting

Use all browser data passed to the server (not just user agent, but also OS, screen resolution, and a number of other things) to generate a unique browser fingerprint.

  • Pros: High probability of being unique, opaque to the end user (changing IP addresses or clearing cookies won’t bypass it)
  • Cons: Probably too unique — any change in browser condition (or browser) will change the fingerprint (though you can choose only a subset of supplied browser information to balance fingerprint volatility and uniqueness), can be bypassed by scripts

You can, of course, also use multiple methods. Which method you use really depends on your specific use case. For many cases, just a simple cookie will do. If you want some defense against scripts or other methods of bypassing, add an IP address rate limit. You can also attempt to gather as much information as possible and use some sort of heuristic algorithm to try to find people that are bypassing the system for uniqueness that you have in place.

What Is the Difference Between Boxed and Tray Processors?

Are there any functional differences between boxed processors and tray processors?

No, there are no functional differences between these two types of processors if they have the same processor number. The main difference is the warranty. For more information on warranties, see the Intel® Boxed vs. Tray Processor Warranty Policy.

Boxed Processor

As a genuine boxed processor from an Intel® Authorized Distributor. Intel Authorized Distributors sell Intel processors in clearly marked boxes from Intel. We refer to these processors as boxed processors. For more details about boxed and tray warranty, visit our warranty policy page.

Boxed processor

Tray Processor

As part of an original equipment manufacturer (OEM) system. Tray processors are sold to high volume manufacturers, such as Acer, ASUS , Dell, Hewlett-Packard or Lenovo. They buy processors in bulk, incorporate them into PCs (laptops, desktops, All-in-Ones). Warranty replacements and technical support for tray processors are provided directly by these providers. We refer to these processors as tray or OEM processors. Intel doesn’t provide direct warranty support. Contact your OEM or reseller for warranty support.

If you have an Intel® Data Center Block system from Intel, you may be eligible for a warranty, please contact Intel Customer Support to determine eligibility.

Tray Processor

php code for generating qr code | It’s worth adding that, in addition to the QR codes library posted by Google

It’s worth adding that, in addition to the QR codes library posted by Google

To use this , basically:

https://chart.googleapis.com/chart?chs=300x300&cht=qr&chl=http%3A%2F%2Fwww.google.com%2F&choe=UTF-8
  • 300x300 is the size of the QR image you want to generate,
  • the chl is the url-encoded string you want to change into a QR code, and
  • the choe is the (optional) encoding.

The link, above, gives more detail, but to use it just have the src of an image point to the manipulated value, like so:

<img src="https://chart.googleapis.com/chart?chs=300x300&cht=qr&chl=http%3A%2F%2Fwww.google.com%2F&choe=UTF-8" title="Link to Google.com" />

Demo:

php code for generating qr code | HP QR Code is open source (LGPL) library for generating

PHP QR Code is open source (LGPL) library for generating QR Code, 2-dimensional barcode. Based on libqrencode C library, provides API for creating QR Code barcode images (PNG, JPEG thanks to GD2). Implemented purely in PHP, with no external dependencies (except GD2 if needed).

Some of library features includes:

  • Supports QR Code versions (size) 1-40
  • Numeric, Alphanumeric, 8-bit and Kanji encoding. (Kanji encoding was not fully tested, if you are japan-encoding enabled you can contribute by verifing it 🙂 )
  • Implemented purely in PHP, no external dependencies except GD2
  • Exports to PNG, JPEG images, also exports as bit-table
  • TCPDF 2-D barcode API integration
  • Easy to configure
  • Data cache for calculation speed-up
  • Provided merge tool helps deploy library as a one big dependency-less file, simple to “include and do not wory”
  • Debug data dump, error logging, time benchmarking
  • API documentation
  • Detailed examples
  • 100% Open Source, LGPL Licensed

buffer cache in linux is increase and get ram usage

Don’t Panic!
Your ram is fine!

What’s going on?

Linux is borrowing unused memory for disk caching. This makes it look like you are low on memory, but you are not! Everything is fine!

Why is it doing this?

Disk caching makes the system much faster and more responsive! There are no downsides, except for confusing newbies. It does not take memory away from applications in any way, ever!

What if I want to run more applications?

If your applications want more memory, they just take back a chunk that the disk cache borrowed. Disk cache can always be given back to applications immediately! You are not low on ram!

Do I need more swap?

No, disk caching only borrows the ram that applications don’t currently want. It will not use swap. If applications want more memory, they just take it back from the disk cache. They will not start swapping.

How do I stop Linux from doing this?

You can’t disable disk caching. The only reason anyone ever wants to disable disk caching is because they think it takes memory away from their applications, which it doesn’t! Disk cache makes applications load faster and run smoother, but it NEVER EVER takes memory away from them! Therefore, there’s absolutely no reason to disable it!

If, however, you find yourself needing to clear some RAM quickly to workaround another issue, like a VM misbehaving, you can force linux to nondestructively drop caches using echo 3 | sudo tee /proc/sys/vm/drop_caches.

Why does top and free say all my ram is used if it isn’t?

This is just a difference in terminology. Both you and Linux agree that memory taken by applications is “used”, while memory that isn’t used for anything is “free”.

But how do you count memory that is currently used for something, but can still be made available to applications?

You might count that memory as “free” and/or “available”. Linux instead counts it as “used”, but also “available”:

Memory that isYou’d call itLinux calls it
used by applicationsUsedUsed
used, but can be made availableFree (or Available)Used (and Available)
not used for anythingFreeFree

This “something” is (roughly) what top and free calls “buffers” and “cached”. Since your and Linux’s terminology differs, you might think you are low on ram when you’re not.

How do I see how much free ram I really have?

To see how much ram your applications could use without swapping, run free -m and look at the “available” column:

  $ free -m
                total        used        free      shared  buff/cache   available
  Mem:           1504        1491          13           0         855      792
  Swap:          2047           6        2041

(On installations from before 2016, look at “free” column in the “-/+ buffers/cache” row instead.)

This is your answer in MiB. If you just naively look at “used” and “free”, you’ll think your ram is 99% full when it’s really just 47%!

For a more detailed and technical description of what Linux counts as “available”, see the commit that added the field.

When should I start to worry?

A healthy Linux system with more than enough memory will, after running for a while, show the following expected and harmless behavior:

  • free memory is close to 0
  • used memory is close to total
  • available memory (or “free + buffers/cache”) has enough room (let’s say, 20%+ of total)
  • swap used does not change

Warning signs of a genuine low memory situation that you may want to look into:

  • available memory (or “free + buffers/cache”) is close to zero
  • swap used increases or fluctuates
  • dmesg | grep oom-killer shows the OutOfMemory-killer at work

How can I verify these things?

See this page for more details and how you can experiment with disk cache to show the effects described here. Few things make you appreciate disk caching more than measuring an order-of-magnitude speedup on your own hardware!

NRF51822 Bluetooth BLE4 2.4GHz Wireless Communication Module

NRF51822 Bluetooth BLE4 2.4GHz Wireless Communication Module

The NRF51822 IC from Nordic Semiconductor is a powerful, highly flexible multiprotocol SoC ideally suited for Bluetooth® Low Energy and 2.4GHz ultra low-power wireless applications. The nRF51822 is built around a 32-bit ARM® Cortex™ M0 CPU with 256kB/128kB flash + 32kB/16kB RAM for improved application performance. The embedded 2.4GHz transceiver supports both Bluetooth LE and the Nordic Gazell 2.4 GHz protocol stack which is on air compatible with the nRF24L series products from Nordic Semiconductor.

Specifications of NRF51822 Bluetooth BLE4 2.4GHz Wireless Communication Module:-

  • Onboard chip: nRF51822
  • Communication distance (open outdoor@1M data rate): 30 m
  • Frequency range: 2.4GHz
  • Operating voltage: 2.0 Volts to 3.6 volts
  • Operating temperature: -40° ~ 85°
  • Expansion pin header: all the I/Os except P0.26 and P0.27
  • Pinheader pitch: 2.00 mm
  • Spacing between pin headers on the left side and the right side: 18.00mm
  • Antenna: onboard antenna 

Features of NRF51822 Bluetooth BLE4 2.4GHz Wireless Communication Module:- 

  • 2.4 GHz multiprotocol RF transceiver
  • 128 bit AES HW encryption
  • 256kB flash & 16kB RAM
  • Programmable Peripheral Interconnect (PPI)
  • Digital interfaces: SPI, I2C, UART
  • 10 bit ADC
  • Programmable output power: -20 to +4 dBm
  • Independent application development and protocol stack
  • Fully compatible with NRF24L series
  • Pinout compatible with NRF51xxx series
  • Global separate power management
  • Operating voltage: 1.8 V ~ 3.6 V 

Applications of NRF51822 Bluetooth BLE4 2.4GHz Wireless Communication Module:- 

  • Wearable devices
  • Bluetooth intelligent application
  • Mobile phone accessories
  • RFID labels
  • Smart home appliances
  • Industry control
  • Data acquisition system

* Product Images are shown for illustrative purposes only and may differ from actual product.

Click

HM-10 Bluetooth Module

HM-10 Bluetooth Module

The HM-10 Bluetooth module combines the powerful and programmable Texas Instruments CC2541 Chipset with the required components to start right away with your BLE development.The module offers an on-board voltage regulator and is TTL-level and 5 V tolerant. The Bluetooth-SoC can be accessed via UART interface and supports AT-Commands for setup. It supports full Bluetooth 4.0 standard and can be used for your Arduino or microcontroller to Android or iOS communication projects.This module can be used to replace HC-05, HC-06 and HC-07 devices.This module can also be configured and used as an iBeacon used with Apple devices.

Features of HM-10 Bluetooth Module:-

  • BT Version: Bluetooth Specification V4.0 BLE
  • Send and receive no bytes limit.
  • Working frequency: 2.4GHz ISM band
  • Modulation method: GFSK(Gaussian Frequency Shift Keying)
  • RF Power: -23dbm, -6dbm, 0dbm, 6dbm, can modify through AT Command AT+POWE.
  • Speed: Asynchronous: 6K Bytes
  • Synchronous: 6K Bytes
  • Security: Authentication and encryption
  • Service: Central & Peripheral UUID FFE0,FFE1
  • Power: +3.3VDC 50mA
  • Long range: Open space have 100 Meters with iphone4s
  • Power: In sleep mode 400uA~1 .5mA, Active mode 8.5mA.
  • Working temperature:–5 ~ +65 Centigrade
  • Size: HM-10 26.9mm x 1 3mm x 2.2 mm;

Note:- This is a Compatible / Clone Model of HM-10 Module

Click

Wireshark 3.6.0 Release Notes

Wireshark 3.6.0 Release Notes

What is Wireshark?

Wireshark is the world’s most popular network protocol analyzer. It is
used for troubleshooting, analysis, development and education.

What’s New

Many improvements have been made. See the “New and Updated Features”
section below for more details. You might want to pay particular
attention to the display filter syntax updates.

New and Updated Features

The following features are new (or have been significantly updated)
since version 3.6.0rc3:

 • The macOS Intel packages now ship with Qt 5.15.3 and require
   macOS 10.13 or later.

The following features are new (or have been significantly updated)
since version 3.6.0rc2:

 • Display filter set elements must now be comma-separated. See
   below for more details.

The following features are new (or have been significantly updated)
since version 3.6.0rc1:

 • The display filter expression “a != b” now has the same meaning
   as “!(a == b)”.

The following features are new (or have been significantly updated)
since version 3.5.0:

 • Nothing of note.

The following features are new (or have been significantly updated)
since version 3.4.0:

 • Several changes have been made to the display filter syntax:

    • The expression “a != b” now always has the same meaning as
   “!(a == b)”. In particular this means filter expressions with
   multi-value fields like “ip.addr != 1.1.1.1” will work as
   expected (the result is the same as typing “ip.src != 1.1.1.1 and
   ip.dst != 1.1.1.1”). This avoids the contradiction (a == b and a
   != b) being true.

    • It is possible to use the syntax “a ~= b” or “a any_ne b” to
   recover the previous (inconsistent with "==") logic for not
   equal.

    • Literal strings can now be specified using raw string syntax,
   identical to raw strings in the Python programming language. This
   can be used to avoid the complexity of using two levels of
   character escapes with regular expressions.

    • Set elements must now be separated using a comma. A filter
   such as http.request.method in {"GET" "HEAD"} must be written as
   …​ in {"GET", "HEAD"}. Whitespace is not significant. The
   previous use of whitespace as separator is deprecated and will be
   removed in a future version.

    • Support for the syntax "a not in b" with the same meaning as
   "not a in b" has been added.

 • Packaging updates:

    • A macOS Arm 64 (Apple Silicon) package is now available.

    • The macOS Intel packages now ship with Qt 5.15.3 and require
   macOS 10.13 or later.

    • The Windows installers now ship with Npcap 1.55.

    • A 64-bit Windows PortableApps package is now available.

 • TCP conversations now support a completeness criteria, which
   facilitates the identification of TCP streams having any of
   opening or closing handshakes, a payload, in any combination. It
   can be accessed with the new tcp.completeness filter.

 • Protobuf fields that are not serialized on the wire or otherwise
   missing in capture files can now be displayed with default values
   by setting the new “add_default_value” preference. The default
   values might be explicitly declared in “proto2” files, or false
   for bools, first value for enums, zero for numeric types.

 • Wireshark now supports reading Event Tracing for Windows (ETW). A
   new extcap named ETW reader is created that now can open an etl
   file, convert all events in the file to DLT_ETW packets and write
   to a specified FIFO destination. Also, a new packet_etw dissector
   is created to dissect DLT_ETW packets so Wireshark can display
   the DLT_ETW packet header, its message and packet_etw dissector
   calls packet_mbim sub_dissector if its provider matches the MBIM
   provider GUID.

 • “Follow DCCP stream” feature to filter for and extract the
   contents of DCCP streams.

 • Wireshark now supports dissecting RTP packets with OPUS payloads.

 • Importing captures from text files based on regular expressions
   is now possible. By specifying a regex capturing a single packet
   including capturing groups for relevant fields a textfile can be
   converted to a libpcap capture file. Supported data encodings are
   plain-hexadecimal, -octal, -binary and base64. Also the timestamp
   format now allows the second-fractions to be placed anywhere in
   the timestamp and it will be stored with nanosecond instead of
   microsecond precision.

 • The RTP Player has been significatnly redesigned and improved.
   See Playing VoIP Calls[1] and RTP Player Window[2] in the User’s
   Guide for more details.

    • The RTP Player can play many streams in row.

    • The UI is more responsive.

    • The RTP Player maintains playlist and other tools can add and
   remove streams to and from it.

    • Every stream can be muted or routed to the left or right
   channel for replay.

    • The option to save audio has been moved from the RTP Analysis
   dialog to the RTP Player. The RTP Player also saves what was
   played, and it can save in multichannel .au or .wav.

    • The RTP Player is now accessible from the Telephony › RTP ›
   RTP Player menu.

 • The VoIP dialogs (VoIP Calls, RTP Streams, RTP Analysis, RTP
   Player, SIP Flows) are non-modal and can stay opened on
   background.

    • The same tools are provided across all dialogs (Prepare
   Filter, Analyse, RTP Player …​)

 • The “Follow Stream” dialog is now able to follow SIP calls based
   on their Call-ID value.

 • The “Follow Stream” dialog’s YAML output format has been updated
   to add timestamps and peers information For more details see
   Following Protocol Streams[3] in the User’s Guide.

 • IP fragments between public IPv4 addresses are now reassembled
   even if they have different VLAN IDs. Reassembly of IP fragments
   where one endpoint is a private (RFC 1918 section 3) or
   link-local (RFC 3927) IPv4 address continues to take the VLAN ID
   into account, as those addresses can be reused. To revert to the
   previous behavior and not reassemble fragments with different
   VLAN IDs, turn on the “Enable stricter conversation tracking
   heuristics” top level protocol preference.

 • USB Link Layer reassembly has been added, which allows hardware
   captures to be analyzed at the same level as software captures.

 • TShark can now export TLS session keys with the
   --export-tls-session-keys option.

 • Wireshark participated in the Google Season of Docs 2020 and the
   User’s Guide has been extensively updated.

 • The “RTP Stream Analysis” dialog CSV export format was slightly
   changed. The first line of the export contains column titles as
   in other CSV exports.

 • Wireshark now supports the Turkish language.

 • The settings in the “Import from Hex Dump” dialog is now stored
   in a profile import_hexdump.json file.

 • Analyze › Reload Lua Plugins has been improved to properly
   support FileHandler.

 • The “RTP Stream Analysis” and “IAX2 Stream Analysis” dialogs now
   show correct calculation mean jitter calculations.

 • RTP streams are now created based on Skinny protocol messages in
   addition to other types of messages.

 • The “VoIP Calls Flow Sequence” window shows more information
   about various Skinny messages.

 • Initial support for building Wireshark on Windows using GCC and
   MinGW-w64 has been added. See README.msys2 in the sources for
   more information.

New File Format Decoding Support

Vector Informatik Binary Log File (BLF)

New Protocol Support

5G Lawful Interception (5GLI), Bluetooth Link Manager Protocol (BT
LMP), Bundle Protocol version 7 (BPv7), Bundle Protocol version 7
Security (BPSec), CBOR Object Signing and Encryption (COSE), E2
Application Protocol (E2AP), Event Tracing for Windows (ETW), EXtreme
extra Eth Header (EXEH), High-Performance Connectivity Tracer
(HiPerConTracer), ISO 10681, Kerberos SPAKE, Linux psample protocol,
Local Interconnect Network (LIN), Microsoft Task Scheduler Service,
O-RAN E2AP, O-RAN fronthaul UC-plane (O-RAN), Opus Interactive Audio
Codec (OPUS), PDU Transport Protocol, R09.x (R09), RDP Dynamic
Channel Protocol (DRDYNVC), RDP Graphic pipeline channel Protocol
(EGFX), RDP Multi-transport (RDPMT), Real-Time Publish-Subscribe
Virtual Transport (RTPS-VT), Real-Time Publish-Subscribe Wire
Protocol (processed) (RTPS-PROC), Shared Memory Communications (SMC),
Signal PDU, SparkplugB, State Synchronization Protocol (SSyncP),
Tagged Image File Format (TIFF), TP-Link Smart Home Protocol, UAVCAN
DSDL, UAVCAN/CAN, UDP Remote Desktop Protocol (RDPUDP), Van Jacobson
PPP compression (VJC), World of Warcraft World (WOWW), and X2 xIRI
payload (xIRI)

Updated Protocol Support

Too many protocols have been updated to list here.

New and Updated Capture File Support

Vector Informatik Binary Log File (BLF)

Getting Wireshark

Wireshark source code and installation packages are available from
https://www.wireshark.org/download.html.

Vendor-supplied Packages

Most Linux and Unix vendors supply their own Wireshark packages. You
can usually install or upgrade Wireshark using the package management
system specific to that platform. A list of third-party packages can
be found on the download page[4] on the Wireshark web site.

File Locations

Wireshark and TShark look in several different locations for
preference files, plugins, SNMP MIBS, and RADIUS dictionaries. These
locations vary from platform to platform. You can use Help › About
Wireshark › Folders or tshark -G folders to find the default locations
on your system.

Getting Help

The User’s Guide, manual pages and various other documentation can be
found at https://www.wireshark.org/docs/

Community support is available on Wireshark’s Q&A site[5] and on the
wireshark-users mailing list. Subscription information and archives
for all of Wireshark’s mailing lists can be found on the web site[6].

Bugs and feature requests can be reported on the issue tracker[7].

Frequently Asked Questions

A complete FAQ is available on the Wireshark web site[8].

Last updated 2021-11-22 18:33:14 UTC

References

  1. https://www.wireshark.org/docs/wsug_html_chunked/ChTelPlayingCalls
    .html
  2. https://www.wireshark.org/docs/wsug_html_chunked/_rtp.html#ChTelRt
    pPlayer
  3. https://www.wireshark.org/docs/wsug_html_chunked/ChAdvFollowStream
    Section.html
  4. https://www.wireshark.org/download.html
  5. https://ask.wireshark.org/
  6. https://www.wireshark.org/lists/
  7. https://gitlab.com/wireshark/wireshark/-/issues
  8. https://www.wireshark.org/faq.html

User Generated Content

User Generated Content

User-generated content (UGC) is content that users contribute to an app, and which is visible to or accessible by at least a subset of the app’s users.

Apps that contain or feature UGC must:

  • require that users accept the app’s terms of use and/or user policy before users can create or upload UGC;
  • define objectionable content and behaviors (in a way that complies with Play’s Developer Program Policies), and prohibit them in the app’s terms of use or user policies;
  • implement robust, effective and ongoing UGC moderation, as is reasonable and consistent with the type of UGC hosted by the app
    • In the case of live-streaming apps, objectionable UGC must be removed as close to real-time as reasonably possible;
    • In the case of augmented reality (AR) apps, UGC moderation (including the in-app reporting system) must account for both objectionable AR UGC (e.g. a sexually explicit AR image) and sensitive AR anchoring location (e.g. AR content anchored to a restricted area, such as a military base, or a private property where AR anchoring may cause issues for the property owner);
  • provide a user-friendly, in-app system for reporting objectionable UGC and take action against that UGC where appropriate;
  • remove or block abusive users who violate the app’s terms of use and/or user policy;
  • provide safeguards to prevent in-app monetization from encouraging objectionable user behavior.

Apps whose primary purpose is featuring objectionable UGC will be removed from Google Play. Similarly, apps that end up being used primarily for hosting objectionable UGC, or that develop a reputation among users of being a place where such content thrives, will also be removed from Google Play.

follow link for detail

Invoke-customs are only supported starting with Android O (–min-api 26)

It is also necessary to set the minSdkVersion and targetSdkVersion according to the min api reported in the error message. build.gradle : defaultConfig { applicationId “com.mypack.myapp” minSdkVersion 26 targetSdkVersion 29 versionCode 1 versionName “2.0”

After hours of struggling, I solved it by including the following within app/build.gradle:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}