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@jboner
jboner / latency.txt
Last active May 3, 2024 15:17
Latency Numbers Every Programmer Should Know
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
@amitsaha
amitsaha / tail.py
Last active April 30, 2024 11:49
Simple implementation of the tail command in Python
'''
Basic tail command implementation
Usage:
tail.py filename numlines
'''
import sys
import linecache
@denji
denji / golang-tls.md
Last active April 29, 2024 03:39 — forked from spikebike/client.go
Simple Golang HTTPS/TLS Examples

Moved to git repository: https://github.com/denji/golang-tls

Generate private key (.key)
# Key considerations for algorithm "RSA" ≥ 2048-bit
openssl genrsa -out server.key 2048

# Key considerations for algorithm "ECDSA" ≥ secp384r1
# List ECDSA the supported curves (openssl ecparam -list_curves)
@taoyuan
taoyuan / npm-using-https-for-git.sh
Last active April 27, 2024 01:22
Force git to use https:// instead of git://
# npm using https for git
git config --global url."https://github.com/".insteadOf git@github.com:
git config --global url."https://".insteadOf git://
# npm using git for https
git config --global url."git@github.com:".insteadOf https://github.com/
git config --global url."git://".insteadOf https://
@so0k
so0k / kubectl.md
Last active April 25, 2024 12:40
Playing with kubectl output

Kubectl output options

Let's look at some basic kubectl output options.

Our intention is to list nodes (with their AWS InstanceId) and Pods (sorted by node).

We can start with:

kubectl get no
@asukakenji
asukakenji / 0-go-os-arch.md
Last active April 24, 2024 06:51
Go (Golang) GOOS and GOARCH

Go (Golang) GOOS and GOARCH

All of the following information is based on go version go1.17.1 darwin/amd64.

GOOS Values

GOOS Out of the Box
aix
android
@mpneuried
mpneuried / Makefile
Last active April 19, 2024 21:06
Simple Makefile to build, run, tag and publish a docker containier to AWS-ECR
# import config.
# You can change the default config with `make cnf="config_special.env" build`
cnf ?= config.env
include $(cnf)
export $(shell sed 's/=.*//' $(cnf))
# import deploy config
# You can change the default deploy config with `make cnf="deploy_special.env" release`
dpl ?= deploy.env
include $(dpl)
@ravibhure
ravibhure / git_rebase.md
Last active April 3, 2024 08:38
Git rebase from remote fork repo

In your local clone of your forked repository, you can add the original GitHub repository as a "remote". ("Remotes" are like nicknames for the URLs of repositories - origin is one, for example.) Then you can fetch all the branches from that upstream repository, and rebase your work to continue working on the upstream version. In terms of commands that might look like:

Add the remote, call it "upstream":

git remote add upstream https://github.com/whoever/whatever.git

Fetch all the branches of that remote into remote-tracking branches, such as upstream/master:

git fetch upstream

@hongster
hongster / tcp_timeout.go
Created October 2, 2015 11:30
Golang example on handling TCP connection and setting timeout.
package main
import (
"fmt"
"net"
"time"
"bufio"
)
func handleConnection(conn net.Conn) {

WannaCry|WannaDecrypt0r NSA-Cyberweapon-Powered Ransomware Worm

  • Virus Name: WannaCrypt, WannaCry, WanaCrypt0r, WCrypt, WCRY
  • Vector: All Windows versions before Windows 10 are vulnerable if not patched for MS-17-010. It uses EternalBlue MS17-010 to propagate.
  • Ransom: between $300 to $600. There is code to 'rm' (delete) files in the virus. Seems to reset if the virus crashes.
  • Backdooring: The worm loops through every RDP session on a system to run the ransomware as that user. It also installs the DOUBLEPULSAR backdoor. It corrupts shadow volumes to make recovery harder. (source: malwarebytes)
  • Kill switch: If the website www.iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com is up the virus exits instead of infecting the host. (source: malwarebytes). This domain has been sinkholed, stopping the spread of the worm. Will not work if proxied (source).

update: A minor variant of the viru