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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

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Create the directory for the new instance

$ sudo install -o redis -g redis -d /var/lib/redis2

Create a new configuration file

$ sudo cp -p /etc/redis/redis.conf /etc/redis/redis2.conf

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Create Root CA (Done once)

Create Root Key

Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!

openssl genrsa -des3 -out rootCA.key 4096

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To limit a CPU to a certain C-state, you can pass the processor.max_cstate=X option in the kernel line of /boot/grub/grub.conf.

Here we limit the system to only C-State 1:

    kernel /vmlinuz-2.6.18-371.1.2.el5 ... processor.max_cstate=1

On some systems, the kernel can override the BIOS setting, and the parameter intel_idle.max_cstate=0 may be required to ensure sleep states are not entered:

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The shadowsocks protocol is very similar to SOCKS5 but encrypted and simpler.

Below is the structure of a shadowsocks request (sent from client-side), which is identical for both TCP and UDP connections before encrypted (or after decrypted).

+--------------+---------------------+------------------+----------+
| Address Type | Destination Address | Destination Port |   Data   |
+--------------+---------------------+------------------+----------+
|      1       |       Variable      |         2        | Variable |
+--------------+---------------------+------------------+----------+

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#!/usr/bin/env bash

# Step 1: Fill in EMAIL, TOKEN, DOMAIN and SUBDOMAIN. Your API token is here: https://www.cloudflare.com/a/account/my-account
#         Make sure the token is the Global token, or has these permissions: #zone:read, #dns_record:read, #dns_records:edit
# Step 2: Create an A record on Cloudflare with the subdomain you chose
# Step 3: Run "./ddns.sh -l" to get the zone_id and rec_id of the record you created.
#         Fill in ZONE_ID and REC_ID below
#         This step is optional, but will save you 2 requests every time you this script
# Step 4: Run "./ddns.sh". It should tell you that record was updated or that it didn't need updating.
# Step 5: Run it every hour with cron. Use the '-s' flag to silence normal output

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import sys

# choose() is the same as computing the number of combinations. Normally this is
# equal to:
#
#   factorial(N) / (factorial(m) * factorial(N - m))
#
# but this is very slow to run and requires a deep stack (without tail
# recursion).
#

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Author: David Manouchehri <manouchehri@protonmail.com>
# This script will always echo back data on the UDP port of your choice.
# Useful if you want nmap to report a UDP port as "open" instead of "open|filtered" on a standard scan.
# Works with both Python 2 & 3.

import socket