RSA in 5 lines of perl

#!/usr/local/bin/perl -s do 'bigint.pl';

($_,$n)=@ARGV;s/^.(..)*$/0$&/;

($k=unpack('B*',pack('H*',$_)))=~ s/^0*//;

$x=0;$z=$n=~s/./$x=&badd(&bmul($x,16),hex$&)/ge;

while(read(STDIN,$_,$w =((2*$d-1+$z)&~1)/2)){$r=1;$_=substr($_."\0"x$w,$c=0,$w);

s/.|\n/$c=&badd(&bmul ($c,256),ord$&)/ge;$_=$k;s/./$r=&bmod(&bmul($r,$r),$x),$&?$r=&bmod(&bmul($r,$c ),$x):0,""/ge;($r,$t)=&bdiv($r,256),$_=pack(C,$t).$_ while$w--+1-2*$d;print}

Source: RSA in 5 lines of perl

A DIY Internet Network Has Drastically Expanded Its Coverage in NYC

Initially, the mesh network was powered by a single “Supernode” antenna and hardware array located at 375 Pearl Street in Manhattan. This gigabit fiber-fed antenna connects 300 buildings, where members have mounted routers on a rooftop or near a window. These local “nodes” in turn connect to an internet exchange point—without the need for a traditional ISP.

Source: A DIY Internet Network Has Drastically Expanded Its Coverage in NYC – VICE

Raspberry Pi 4 on sale now from $35

Raspberry Pi 4 Model B

Here are the highlights:

  • A 1.5GHz quad-core 64-bit ARM Cortex-A72 CPU (~3× performance)
  • 1GB, 2GB, or 4GB of LPDDR4 SDRAM
  • Full-throughput Gigabit Ethernet
  • Dual-band 802.11ac wireless networking
  • Bluetooth 5.0
  • Two USB 3.0 and two USB 2.0 ports
  • Dual monitor support, at resolutions up to 4K
  • VideoCore VI graphics, supporting OpenGL ES 3.x
  • 4Kp60 hardware decode of HEVC video
  • Complete compatibility with earlier Raspberry Pi products

Source: Raspberry Pi 4 on sale now from $35 – Raspberry Pi

Linux PCs, servers, gadgets can be crashed by ‘Ping of Death’ network packets

With CVE-2019-11477, a string of TCP SACK responses will cause the Linux kernel to unexpectedly hit an internal data structure limit, triggering a fatal panic. The others affecting Linux will force the system to consume resources, thus slowing it down, as Red Hat explained in its technical summary today.

Source: Sad SACK: Linux PCs, servers, gadgets can be crashed by ‘Ping of Death’ network packets • The Register

How to Free up Unused Memory in Ubuntu/Linux Mint

In this tutorial, we will see how to use the terminal to clean up unused memory that was not released properly after being used by your system. No need to use any third-party software, just a few commands will do the job pretty easily.

Source: How to Free up Unused Memory in Ubuntu/Linux Mint

Have a little problem with a server freezing which might be memory related.  This simple tutorial was very helpful.

You can free up unused memory under Ubuntu/Linux Mint using this command:

sudo sysctl -w vm.drop_caches=3

SpaceX launches first batch of 60 internet satellites in landmark mission

SpaceX ultimately wants Starlink to grow to include potentially thousands of satellites over the next few years. The company says it could make available low-cost internet for a significant portion of the world’s population that isn’t yet online and offer a competitive alternative for people who aren’t happy with their broadband provider.

Source: SpaceX launches first batch of 60 internet satellites in landmark mission – CNN

AI predicts PUBG player placement from stats and rankings

“In this paper specifically, we have tried to predict the [ranking] of the player in the ultimate survival test,” the project’s contributors wrote in a preprint paper (“Survival of the Fittest in PlayerUnknown’s BattleGrounds“) published on Arxiv.org. “We have applied multiple machine learning models to find the optimum prediction.”

Source: AI predicts PUBG player placement from stats and rankings | VentureBeat