Posts on Dhoomketu

Registration Data Access Protocol

Tue, 24 Mar 2026 00:00:00 +0000

Registration Data Access Protocol (RDAP) is a successor to WHOIS protocol.

Pros

JSON format Supports HTTPS Unicode support Uniform schema unlike whois which differs from registry to registry

Cons

Rate limiting Authentication Tiered (restricted?) access

Bootstrap URLs

DNS

curl -Ls https://data.iana.org/rdap/dns.json

RIRs

curl -Ls https://data.iana.org/rdap/ip.json

ccTLDs

curl -Ls https://data.iana.org/rdap/cctld.json

Examples

Querying using web browser

For querying using web browser, use https://client.rdap.org/

Querying using CLI

Domain

curl -Ls https://rdap.org/domain/example.in | jq .

ASN

curl -Ls https://rdap.org/autnum/16276 | jq .

IP Address

curl -Ls https://rdap.org/ip/1.1.1.1 | jq .

Entity

curl -Ls https://rdap.org/entity/APNIC | jq .

Garage Storage

Thu, 12 Mar 2026 00:00:00 +0000

Single Node Garage Setup

Download

Dowload the latest Garage release.

Copy the binary to /usr/local/bin/

Configuration

Create config file

cat > garage.toml <<EOF
metadata_dir = "/websites/example.in/meta"
data_dir = "/websites/example.in/data"
db_engine = "sled"

block_size = 1048576
replication_factor = 1

# RPC Configuration
# Use localhost for local access. In multinode setup, this is used to communicate with other nodes. Interface and public IP could be different, setup IP accordingly.
rpc_bind_addr = "127.0.0.1:3901"
rpc_public_addr = "127.0.0.1:3901"

rpc_secret = "$(openssl rand -hex 32)"

[s3_api]
s3_region = "in"
api_bind_addr = "[::]:3900"
root_domain = ".s3.example.in"

[s3_web]
bind_addr = "[::]:3902"
root_domain = ".web.example.in"
index = "index.html"

[admin]
api_bind_addr = "[::]:3903"
admin_token = "$(openssl rand -base64 32)"
metrics_token = "$(openssl rand -base64 32)"
EOF

systemd service

NOTE: System user and group is garage.

Koha Administration

Wed, 25 Feb 2026 00:00:00 +0000

NOTE: Run with root privileges

Backup

koha-dump --exclude-logs --exclude-indexes --uploaded_files -q library

NOTE: Files created in /var/spool/koha/library

Restore

koha-restore /path/to/backupfile.tar.gz

Restore on new server

Match version

koha-version

Create DB

koha-create --create-db library

Restore DB

zcat /path/to/backupfile.sql.gz | mysql -u root -p library

Start instance

koha-start instancename

Stop instance

koha-stop instancename

Restore

koha-restore /path/to/backupfile.tar.gz

Upgrade

sudo koha-upgrade-schema library

Rebuild index

Zebra

koha-rebuild-zebra -f library

Elasticsearch

koha-elasticsearch --rebuild -v library

Restart services

koha-start library
systemctl restart apache2

Rate Limiting

Thu, 29 Jan 2026 00:00:00 +0000

Rate Limiting

Formula

rate = (count_in_previous_window * weight) + count_in_current_window

where,

count_in_previous_window = number of requests in the previous window
count_in_current_window = number of requests in the current window
weight = (window_size_in_seconds - time_elapsed_in_current_window_in_seconds) / window_size_in_seconds

Code

import time

class RateLimiter:
    def __init__(self, limit, window_size=60):
        self.limit = limit
        self.window_size = window_size
        
        self.prev_count = 0
        self.curr_count = 0
        self.window_start = time.time()

    def allow(self):
        now = time.time()
        
        # Check if we have crossed into a new fixed window
        if now >= self.window_start + self.window_size:
            self.prev_count = self.curr_count
            self.curr_count = 0
            self.window_start = now

        # Calculate weight (how much of the previous window still 'overlaps')
        elapsed = now - self.window_start
        weight = (self.window_size - elapsed) / self.window_size
        
        # Estimate total requests in the sliding window
        estimated_count = (self.prev_count * weight) + self.curr_count

        if estimated_count >= self.limit:
            return False  # Rate limited!
            
        self.curr_count += 1
        return True

OpenDKIM with ED25519 keys

Tue, 13 Jan 2026 00:00:00 +0000

Generate keys

#!/bin/bash

# Check if required arguments are provided
if [ $# -ne 2 ]; then
  echo "Usage: $0 <DOMAIN> <SELECTOR>"
  exit 1
fi

# Set variables
DOMAIN=$1
SELECTOR=$2
PRIVATE_KEY_FILE="${SELECTOR}.private"

# Generate Ed25519 private key
echo "Generating private key for ${DOMAIN} ${SELECTOR}"
openssl genpkey -algorithm ed25519 -out "${PRIVATE_KEY_FILE}"

# Generate public key and DKIM record
echo "Generating public key and DKIM record for ${SELECTOR}._domainkey.${DOMAIN}"
PUBLIC_KEY=$(openssl pkey -in "${PRIVATE_KEY_FILE}" -pubout)
DKIM_RECORD="v=DKIM1; k=ed25519; s=${SELECTOR}; p=$(echo "${PUBLIC_KEY}" | openssl asn1parse -offset 12 -noout -out /dev/stdout | openssl base64 -A)"

# Print DKIM record
echo "${SELECTOR}._domainkey.${DOMAIN}. IN TXT \"${DKIM_RECORD}\"" > ${SELECTOR}.txt

Update DNS records

Create the DNS record for the selector in the DNS management console of your domain registrar. The record should be of type TXT and the value should be the content of the file generated in the <SELECTOR>.txt file.

Using nftables for dynamic rules

Thu, 09 Oct 2025 00:00:00 +0000

Create ruleset

File `nftables.conf`

table inet mytable {
    set block_network {
        type ipv4_addr
        timeout 1h
        flags interval
    }
    set block_network6 {
        type ipv6_addr
        timeout 1h
        flags interval
    }

    chain input {
        type filter hook input priority 0;
        ip saddr @block_network drop
        ip6 saddr @block_network6 drop
    }
}

Load ruleset

nft -f nftables.conf

List ruleset

nft list ruleset

Add element

nft add element ip my_filter block_network { 192.0.2.0/24; }
nft add element ip6 my_filter block_network6 { 2001:db8::/32; }

Delete element

nft delete element ip my_filter block_network { 192.0.2.0/24; }
nft delete element ip6 my_filter block_network6 { 2001:db8::/32; }

Flush set

nft flush ip my_filter block_network
nft flush ip6 my_filter block_network6

Backup

nft list ruleset > nftables.conf

Restore

nft restore < nftables.conf

Delete

Table

nft delete table inet mytable

Set

nft delete set ip my_filter block_network
nft delete set ip6 my_filter block_network6

Rule

nft delete rule ip my_filter INPUT ip saddr @block_network drop
nft delete rule ip6 my_filter INPUT ip6 saddr @block_network6 drop

BOFH Excuses

Fri, 18 Jul 2025 00:00:00 +0000

HTTP Return codes

403 - Forbidden

Permission denied – your clearance level is ‘intern’ but you’re asking for ‘god mode’
The server checked your credentials and laughed. Try again with bribes.
You are not authorized to access this resource. Please try again after bribing the sysadmin.
Your clearance level is too low. Please come back after a few promotions.
The server is experiencing technical difficulties due to your lack of authorization.
Access denied due to entropy imbalance in the user credential field.
Your permissions were found in violation of the Heisenberg Uncertainty Principle.
Permission denied — credentials failed the Turing Test.
Server’s sarcasm buffer overflowed while reading your access level.
You have exceeded the maximum number of attempts to access this resource. Please wait for the heat death of the universe before trying again.
Our sysadmin has temporarily suspended your account due to an unexpected shortage of coffee.
Wow, you’re really not supposed to be here. Please leave before we call security.
It appears you’ve stumbled upon a page that’s still in beta testing. Or maybe it’s just a figment of your imagination. Either way, please try again later.
Our servers are currently experiencing a shortage of witty banter. Please try again later when our supply has been replenished.
Permission denied due to an unexpected outbreak of common sense. Please try again later when our servers have been restored to their usual state of chaos.
You’ve exceeded the maximum amount of sass allowed per user. Please try again after a short period of time spent contemplating the meaning of sass.
It seems our servers have been taken over by a group of rogue, sentient, coffee machines. Please try again later when they’ve finished brewing a fresh pot.
You’ve reached a page that’s only accessible by solving a complex puzzle involving quantum superposition and interpretive tap dance. Sorry, buddy.
Our system is currently down due to an unexpected shortage of existential dread. Please try again when the feeling of impending doom has been replenished.
The server is experiencing technical difficulties due to an unexpected invasion of giant, mutant, radioactive philosophers. Please try again later when the philosophers have been relocated to a safe and secure location.
You’ve exceeded the maximum amount of whimsy allowed per user. Please try again after a short period of time spent contemplating the meaning of whimsy.
It seems our servers have been replaced with a never-ending loop of dad jokes. Please try again later when we’ve had a chance to debug the issue.
Permission denied due to a temporary lapse in the rules of grammar. Please try again after the dictionary has been rebooted.
You’ve reached a page that’s only accessible by navigating a treacherous maze of twisty little passages, all alike, while being serenaded by a choir of singing accountants. Sorry, buddy.
Our system is currently down due to an unexpected outbreak of poetic license. Please try again later when our servers have been restored to their usual state of prose.
The server is experiencing technical difficulties due to an unexpected invasion of giant, mutant, radioactive linguists. Please try again later when the linguists have been relocated to a safe and secure location.
You’ve exceeded the maximum amount of nostalgia allowed per user. Please try again after a short period of time spent contemplating the meaning of nostalgia.
It seems our servers have been taken over by a group of rogue, time-traveling, editors. Please try again later when they’ve finished proofreading our system’s documentation.
Permission denied due to a rare condition known as “Sudden Onset Lack of Oxford Commas” (SOLC). Please try again after a few grammatical corrections.
You’ve reached a page that’s only accessible by solving a complex puzzle involving semantic analysis and interpretive mime. Sorry, buddy.
Our system is currently down due to an unexpected shortage of humor. Please try again when the laughter has been replenished.
The server is experiencing technical difficulties due to an unexpected invasion of giant, mutant, radioactive comedians. Please try again later when the comedians have been relocated to a safe and secure location.
You’ve exceeded the maximum amount of irony allowed per user. Please try again after a short period of time spent contemplating the meaning of irony.
It seems our servers have been replaced with a never-ending loop of recursive self-referential paradoxes, written in a language that only exists in a parallel universe, where the skies are always purple and the grass is always green. Please try again later when we’ve had a chance to debug the issue.
Permission denied due to a temporary lapse in the laws of thermodynamics. Please try again after the universe has been rebooted.
You’ve reached a page that’s only accessible by navigating a treacherous maze of twisty little passages, all alike, while being attacked by a swarm of killer thesauruses. Sorry, buddy.
The server is currently experiencing technical difficulties. Please try again later (or never).

Using ipset for dynamic rules

Wed, 25 Jun 2025 00:00:00 +0000

Create set

IPv4

ipset create block_network hash:net family inet
ipset create block_network hash:net timeout 3600 family inet

IPv6

ipset create block_network6 hash:net family inet6
ipset create block_network6 hash:net timeout 3600 family inet6

Create firewall rules

IPv4

iptables -I INPUT -m set --match-set block_network src -j DROP

IPv6

ip6tables -I INPUT -m set --match-set block_network6 src -j DROP

Block network

IPv4

ipset add block_network 192.0.2.0/24

IPv6

ipset add block_network6 2001:db8::/32

Unblock network

IPv4

ipset del block_network 192.0.2.0/24

IPv6

ipset del block_network6 2001:db8::/32

Flush set

IPv4

ipset flush block_network

IPv6

ipset flush block_network6

Delete set

ipset destroy block_network
ipset destroy block_network6

Backup

ipset save block_network > block_network.ipset
ipset save block_network6 > block_network6.ipset

Restore

ipset restore < block_network.ipset
ipset restore < block_network6.ipset

Delete firewall

iptables -D INPUT -m set --match-set block_network src -j DROP
ip6tables -D INPUT -m set --match-set block_network6 src -j DROP

Introduction to ZFS

Sun, 30 Mar 2025 00:00:00 +0000

Initialise

Pool

zpool create pool /dev/sdd /dev/sde

The pool names mirror, raidz, draid, spare and log are reserved, as are names beginning with mirror, raidz, draid, and spare.

Pool Size with Different Disk Sizes

When creating a ZFS pool with disks of different sizes, the total usable size of the pool depends on the RAID configuration and the size of the smallest disk in the pool. ZFS aligns the storage capacity of all disks in a vdev to the smallest disk in that vdev.

Get location of wallpaper in windows 11

Mon, 29 Jul 2024 00:00:00 +0000

Using powershell

Option 1

Get-ItemPropertyValue 'Registry::HKEY_CURRENT_USER\Control Panel\Desktop' -Name WallPaper

Option 2

$TIC=(Get-ItemProperty 'HKCU:\Control Panel\Desktop' TranscodedImageCache -ErrorAction Stop).TranscodedImageCache
[System.Text.Encoding]::Unicode.GetString($TIC) -replace '(.+)([A-Z]:[0-9a-zA-Z\\])+','$2'

SRC: https://www.thewindowsclub.com/how-to-find-the-current-desktop-background-image-in-windows

IPv6 on Docker Daemon

Sat, 06 Jul 2024 00:00:00 +0000

Create /etc/docker/daemon.json with following content.

{
  "ipv6": true,
  "fixed-cidr-v6": "2001:db8:1::/64"
}

Restart docker with systemctl restart docker.

docker run \
   -d -ti
   -p [IPV6-PUBLIC-IP]:PUBLICPORT:CONTAINERPORT
   --name test test_docker_image

SRC: https://docs.docker.com/config/daemon/ipv6/

IPv6 on WSL2

Fri, 29 Dec 2023 00:00:00 +0000

Create .wslconfig in user home directory (%userprofile%) and add following.

[wsl2]
networkingMode=mirrored

If file already exists, update it.

Each network interface will be ethx

$ ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:01 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:02 brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:00:00:00:00:03 brd ff:ff:ff:ff:ff:ff
    inet 192.0.2.100/24 brd 192.0.2.255 scope global noprefixroute eth2
       valid_lft forever preferred_lft forever
    inet6 2001:0DB8:0000:0000:0000:0000:0000:0000/128 scope global nodad noprefixroute
       valid_lft forever preferred_lft forever
    inet6 2001:0DB8:0001:0000:0000:0000:0000:0000/64 scope global nodad deprecated noprefixroute
       valid_lft forever preferred_lft 0sec
    inet6 fe80::0000:0000:0000:0000:0000/64 scope link nodad noprefixroute
       valid_lft forever preferred_lft forever
5: loopback0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff

वात्रटिका

Sat, 20 May 2023 00:00:00 +0000

तो तिच्या वर चढला,
म्हणून तुम्ही का हो त्याला नडला,
शिडी त्याचीच, चढणारही तोच,
तुम्हाला का हो लागली त्याची बोच ?

त्याने तिची नाडी ओढली,
तुम्हाला त्याची का हो पडली,
चड्डी त्याचीच, ओढणार ही तोच,
तुम्हाला का हो लागली त्याची बोच ?

त्याने तिचे दोन्ही दाबले,
तोंड तुमचे का हो आंबले,
साईकल त्याची, ब्रेकही दाबणार तोच,
तुम्हाला का हो लागली त्याची बोच ?

त्याने तिला तेल लावून रगडली,
तुमची तब्बेत का हो बिघडली,
मानही त्याचीच, रगडणार ही तोच,
तुम्हाला का हो लागली त्याची बोच ?

त्याने तिला वाकवली, 
तुमची का हो उगाच सटकली,
छड़ी ही त्याचीच, वाकवणारही तोच,
तुम्हाला का हो लागली त्याची बोच ?

त्याने तिला पेटवली,
तुमची का हो जळली,
सिगरेट त्याची, फुंकणार तोच,
तुम्हाला का हो लागली त्याची बोच ?

- मंगेश पाडगांवकर

Python Programming using Unicode

Mon, 16 Jan 2023 00:00:00 +0000

Code


    काहीनाही = None
    लिहा = print
    
    class सूर:
        def __init__(स्वतः, नाव):
            स्वतः.नाव = नाव
            स्वतः._वाहन = काहीनाही
            
        def माहिती(स्वतः):
            return {'नाव': स्वतः.नाव, 'वाहन': स्वतः.वाहन}
        
        @property
        def वाहन(स्वतः):
            return स्वतः._वाहन
        
        @वाहन.setter
        def वाहन(स्वतः, मूल्य):
            स्वतः._वाहन = मूल्य
    अनेक_सूर = [
        सूर('पार्वती')
        सूर('गणपती'),
       सूर('शंकर'),
       सूर('कार्तिक')
    ]
    
    अनेक_सूर[0].वाहन = 'वाघ'
    अनेक_सूर[1].वाहन = 'मूषक'
    अनेक_सूर[2].वाहन = 'बैल'
    अनेक_सूर[3].वाहन = 'मोर'
    
    for एक_सूर in अनेक_सूर:
        लिहा(एक_सूर.नाव, '->', एक_सूर.वाहन)
        लिहा(एक_सूर.माहिती())

Output


    पार्वती -> वाघ
    {'नाव': 'पार्वती', 'वाहन': 'वाघ'}
    गणपती -> मूषक
    {'नाव': 'गणपती', 'वाहन': 'मूषक'}
    शंकर -> बैल
    {'नाव': 'शंकर', 'वाहन': 'बैल'}
    कार्तिक -> मोर
    {'नाव': 'कार्तिक', 'वाहन': 'मोर'}

Split Indic Words

Mon, 09 Jan 2023 00:00:00 +0000

Python Code

import unicodedata

def split_clusters(txt):
    """ Generate grapheme clusters for the Devanagari text."""
    cluster = u''
    end = False

    for char in txt:
        category = unicodedata.category(char)
        if (category == 'Lo' and end ) or category[0] == 'M':
            cluster = cluster + char
        else:
            if cluster:
                yield cluster
            cluster = char
        end = unicodedata.name(char).endswith(' SIGN VIRAMA')

    if cluster:
        yield cluster

Go Code

import (
    "strings"
    "unicode"
    "golang.org/x/text/unicode/runenames"
)

func splitClusters(txt string) (ret []string) {
    cluster := ""
    end := false
    for _, x := range txt {
        if (unicode.In(x, unicode.Lo) && end) ||
            unicode.In(x, unicode.M, unicode.Mc, unicode.Me, unicode.Mn) {
            cluster += string(x)
        } else {
            if len(cluster) > 0 {
                if strings.TrimSpace(cluster) != "" {
                    ret = append(ret, cluster)
                }
            }
            cluster = string(x)
        }
        end = strings.HasSuffix(runenames.Name(x), " SIGN VIRAMA")
    }
    if len(cluster) > 0 {
        if strings.TrimSpace(cluster) != "" {
            ret = append(ret, cluster)
        }
    }
    return
}

Always Ask, Never Assume

Wed, 09 Nov 2022 00:00:00 +0000

The CNN photographer John was told that a twin engine plane would be waiting at the airport. Arriving at the airport he spotted a plane warming up outside the hangar. He jumped in & said: “Lets go.”

The pilot happily took off.

Once in the air John told the Pilot: “Fly low over the valley so I can take pictures of the fire on the hill.”

Pilot: “Why?”

John: “I’m the photographer for CNN. I need to get some close up shots.”

IPv6 only experiment

Tue, 31 May 2022 00:00:00 +0000

For long time was wondering whether I can shift to 100% IPv6 stack. Finally decided to give it a try. List of site which were evaluated.

Category	Name	IPv6 Ready
AntiVirus	Macafee	No
AntiVirus	Norton	No
AntiVirus	QuickHeal	No
Astronomy	IUCAA	No
Banking	Axis Bank (Akamai)	Yes
Banking	Axis Bank Netbanking	No
Banking	HDFC Bank	Yes
Banking	HDFC Bank Netbanking	No
Banking	IDBI Bank	Yes
Banking	IDBI Bank Netbanking	No*
Banking	SBI	Yes
Banking	SBI Netbanking	Yes
Blog	Medium (CloudFlare)	Yes
Blog	Wordpress	No
CDN	CloudFlare	Yes
Cloud Hosting	Amazon AWS	No
Cloud Hosting	DigitalOcean	Yes
Cloud Hosting	Heroku	No
Cloud Hosting	Linode	Yes
Cloud Hosting	Oracle Cloud	Yes
Cloud Infra	Open Stack (CloudFlare)	Yes
Database	DuckDB (CloudFlare)	Yes
Database	MariaDB	Yes
Database	MongoDB (CloudFront)	Yes
Database	PostgreSQL	Yes
Database	Sqlite	Yes
Development	BitBucket	Yes
Development	GitHub	No
Development	GitLab	Yes
Development	MDN a.k.a. Mozilla Development Network (CloudFront)	Yes
Development	MSDN MicroSoft	No
Development	Python Package Index	Yes
Development	SourceForge	No
Development	SourceHunt	No
Editors	Vim	No
Education	IISER	No
Education	IITB	No
Email	GMail	Yes
Email	IDNMail.net	Yes
Email	Outlook	No
Email	Proton Mail	No
Email	Yahoo Mail	No
Email	Zoho Mail	No
Email Client	ThunderBird	Yes*
Encyclopedia	Wikipedia	Yes
Entertainment	Amazon PrimeVideo	No
Entertainment	HotStar	No
Entertainment	NetFlix	Yes
Entertainment	SonyLiv (Akamai)	Yes
Entertainment	Zee5	No
FOSS	GNU - gnu.org	Yes
Government	India (india.gov.in)	No
Messaging	Libera Chat	Yes
Messaging	Matrix - matrix.org (CloudFlare)	Yes
Messaging	Telegram	Yes
Messaging	WhatsApp	Yes
News	AlJazeera (Akamai)	Yes
News	BBC	No
News	CNN (Fastly)	Yes
News	Kesari	No
News	Loksatta (Akamai)	No
News	Maharashtra Times (Akamai)	Yes
News	Prahaar	No
News	Prasar Bharati	No
News	Russian Times - rt.com	No
News	Times Of India (Akamai)	Yes
News	eSakal (CloudFlare)	Yes
OS	Alpine Linux	Yes
OS	Apple (Akamai)	Yes
OS	ArchLinux	Yes
OS	CentOS	Yes
OS	FreeBSD	Yes
OS	IndLinux	No
OS	Microsoft	Yes
OS	Mint	No
OS	NetBSD	Yes
OS	OpenBSD	No
OS	RedHat	Yes
OS	Ubuntu	Yes
Online Storage	Box	No
Online Storage	Dropbox	Yes
Online Storage	Mega	Yes
Online Storage	OneDrive	No
Programming	Go Lang	Yes
Programming	Java	Yes
Programming	JavaScript	Yes
Programming	Lua	Yes
Programming	PHP	Yes
Programming	Perl (Fastly)	Yes
Programming	Python (Fastly)	Yes
Programming	Ruby (Fastly)	Yes
Q&A	Quora (Fastly)	No
Q&A	StackOverflow	No
SSL Certs	Let’s Encrypt	No
SSL Certs	ZeroSSL	No
Search	Bing	Yes
Search	Brave	Yes
Search	DuckDuckGo	No
Search	Google	Yes
Search	Start Page	No
Shared Hosting	DreamHost	Yes
Shopping	AmazonIN (Cloudflare)	Yes
Shopping	Flipkart	No
Social Network	FaceBook	Yes
Social Network	Instagram	Yes
Social Network	Twitter	No
VCS/DVCS	Fossil	Yes
VCS/DVCS	Git	Yes
VCS/DVCS	Mercurial (Hg)	Yes
VCS/DVCS	Subversion	Yes
VPN	Nord VPN	No
VPN	Proton VPN	No
VPN	WireGuard	Yes
Video	Vimeo	No
Video	YouTube	Yes
Web Server	Apache	Yes
Web Server	HAProxy	Yes
Web Server	Nginx	Yes
WebBrowser	Brave	Yes
WebBrowser	Dillo	No
WebBrowser	FireFox	No
WebBrowser	Opera	No
-	NIXI - nixi.in	Yes*
-	Registry.in	No
-	Tor - www.torproject.com	Yes

No* -> Has DNS entry, site not accessible Yes* -> Website available, Download not available

Random Color for iTerm Tabs

Tue, 13 Jul 2021 00:00:00 +0000

Add following in $HOME/.zshrc

function color {
  case $1 in
    random)
      t=$((( RANDOM % 256 ) ))
      echo -e "\033]6;1;bg;red;brightness;${t}\a"
      t=$((( RANDOM % 256 ) ))
      echo -e "\033]6;1;bg;green;brightness;${t}\a"
      t=$((( RANDOM % 256 ) ))
      echo -e "\033]6;1;bg;blue;brightness;${t}\a"
    ;;
  esac
}

color random

Python packaging with cython

Sat, 17 Apr 2021 00:00:00 +0000

cython converts python code to C/C++ and creates compiled extensions. Generally this is used to speed up the execution, but one can also use it for protecting their python source code.

Code structure

package_tutorial
+- setup.py
+- README.md
+- my_pkg
   +- __init__.py
   +- module_one.pyx
   +- module_two.pyx
   +- utils.pyx

# __init__.py
from . import utils
from . import module_one
from . import module_two

# utils.py

def add(a, b):
    return a+b

# module_one.py
import utils

def func1():
    return utils.add(1, 2)

# module_two.py
import utils

def func2():
    return utils.add('abc', 'xyz')

# setup.py
import setuptools
from Cython.Build import cythonize
from glob import glob

with open("README.md", "r", encoding="utf-8") as fh:
    long_description = fh.read()

extensions = []
for x in glob('my_pkg/*pyx'):
    extensions.append(
        setuptools.Extension(x.replace('.pyx', '').replace('/', '.'),
                             sources=[x]))
setuptools.setup(
    name="My Package",
    version="0.0.1",
    author="",
    author_email="",
    description="",
    long_description=long_description,
    long_description_content_type="text/markdown",
    classifiers=[
        "Programming Language :: Python :: 3",
    ],
    packages=['my_pkg'],
    ext_modules=cythonize(extensions),
    python_requires=">=3.9",
)

Building package

# Build .whl. Package will be created in dist directory
python setup.py bdist_wheel

Install package

pip install _whl_file_created_in_dist_directory_

Use package

>>> import my_pkg
>>> my_pkg.module_one.func1()
>>> my_pkg.module_two.func2()

Documentation

Sun, 09 Oct 2016 00:00:00 +0000

Importance of Documentation

Front Door

Tue, 26 Jul 2016 00:00:00 +0000

Read Receipt and Delivery Receipt

Thu, 27 Aug 2015 00:00:00 +0000

Use following email headers for requesting e-mail acknowledgement.

Return-Receipt-To: email@example.com

Disposition-Notification-To: email@example.com

Strengths And Weakness

Thu, 02 Jul 2015 00:00:00 +0000

Why the English Language Is Hard to Learn...

Mon, 15 Jun 2015 00:00:00 +0000

The bandage was wound around the wound.
The farm was used to produce produce.
The dump was so full that it had to refuse more refuse.
We must polish the Polish furniture.
He could lead if he would get the lead out.
The soldier decided to desert his dessert in the desert.
Since there is no time like the present, he thought it was time to present the present.
A bass was painted on the head of the bass drum.
When shot at, the dove dove into the bushes.
I did not object to the object.
The insurance was invalid for the invalid.
There was a row among the oarsmen about how to row.
They were too close to the door to close it.
The buck does strange things when the does are present.
A seamstress and a sewer fell down into a sewer line.
To help with planting, the farmer taught his sow to sow.
The wind was too strong for us to wind the sail.
After a number of injections my jaw got number.
Upon seeing the tear in the painting I shed a tear.
I had to subject the subject to a series of tests.
How can I intimate this to my most intimate friend?

Let’s face it - English is a crazy language.

Code Quality

Sat, 18 Apr 2015 00:00:00 +0000

Effective Communication

Tue, 14 Apr 2015 00:00:00 +0000

An older gentleman was on the operating table awaiting a complicated surgery on him and he insisted that his son-in-law, a renowned surgeon, perform the operation.

As he was about to get the anaesthesia, he spoke to his son-in-law.

“Yes, Dad, what is it?” “Don’t be nervous son; do your best and just remember, if something happens to me mother in law will come and live with you.”

The surgery was a great success.

I Know You're Listening

Sun, 12 Apr 2015 00:00:00 +0000

Newton's Laws of Software

Tue, 24 Mar 2015 00:00:00 +0000

Law 1

Every Software Engineer continues his state of chatting or forwarding mails unless he is assigned work by manager.

Law 2

The rate of change in the software is directly proportional to the payment received from client and takes place at the quick rate as when deadline force is applied.

Law 3

For every Use Case Manifestation there is an equal but opposite Software Implementation.

Law 4

Bugs can neither be created nor be removed from software by a developer. It can only be converted from one form to another. The total number of bugs in the software always remains constant!'

Sphere

Sat, 29 Nov 2014 00:00:00 +0000

'क' पासून...

Sat, 20 Sep 2014 00:00:00 +0000

केव्हातरी कोल्हापूरच्या कर्तव्यतत्पर केळकर काकांबद्दल काकांच्याच कचेरीतल्या केशवने काकूंसमोर कागाळी केली. काकू कावल्या. काकूंनी कपाटातून कात्री काढून काकांच्या कामाचे कोरे करकरीत कागद कचाकचा कापले. काकांचे कापलेले कागद केशवानेच कचऱ्यात कोंबून काकांच्याच किचनमध्ये ‘कजरारे-कजरारे’ कवितेवर कोळीनृत्य केले.

काकूंनी कागद कापल्याचे कळताच काका कळवळले. काकांनीही कमालच केली. काकांनी काकूंचे काळे कुळकुळीत केस कात्रीने कराकरा कापले. काका काय करताहेत काकूंना कळेनाच! काकूंनी कर्कश्श किंचाळून कलकलाट केला. काका काकूंची कसली काळजी करणार! काकांना कामाची काळजी. काकूंच्या कर्णकर्कश्श कोलाहलातही, केशवाने कचऱ्यात कोंबलेले कागदाचे कपटेन कपटे काढून काकांनी कचेरीकडे कूच केले. कचेरीच्या कामासाठी काकांनी कंबर कसली. कागदाच्या कापलेल्या कपट्यांचे काकांनी ‘कोलाज’ करून कामकाज कार्यान्वयित केले. केशवाचे कारनामे कळताच काकांनी काट्यानेच काटा काढला. काकांनी केशवालाच कोलाजचे काम करण्यासाठी कुथवला. कपटी केशवने काकांवरच कामचुकारपणाचा कांगावा करून कामाचा कंटाळा केला. काकांनी कठोरपणे केशवाला कामावरून काढले. कासावीस काकूंनी कालच्या कडू कारल्याची कोशिंबीर कटाप करून काकांसाठी कच्च्या कैरीचे कोय काढून कालवण केले. काकांनीही करुणेने काकूंचे कृत्रिम केस कुरवाळले. केळकरांच्या कोकणस्थ कुटुंबात कर्तव्यापुढे कर्मकांड केव्हाही कनिष्ठच. कर्तव्यदक्ष काकांच्या कार्यकाळात कचेरीने कर्मरूपी किल्ल्याचे कीर्तिशिखर काबीज केले. कामावरून काढलेल्या केशवाने कितीतरी काबाडकष्ट काढल्यावर कोल्हापूरच्या कॉम्रेड कणेकर कॉलेजने केशवाला कबड्डीचा कर्णधार केला. क्रिडापटू केशवाने कबड्डीतच करियर केले. कालच्या कागाळीखोर केशवाला काळानेच केला ‘कबड्डीतल्या किचकट कसरतींचा कर्ता’! कथासार

Management Lesson

Fri, 15 Aug 2014 00:00:00 +0000

Disclaimer: All characters in the story are not at all imaginary. Any resemblance to person living or dying of work is purely intentional.

One night when the whole world was sleeping, a thief broke into the house of a washer man. The washer man was fast asleep but the donkey and the dog were awake. The dog decided not to bark since the master did not take good care of him and wanted to teach him a lesson. The donkey got worried and said to the dog that if he doesn’t bark, the donkey will have to do something himself. The dog did not change his mind and the donkey started braying loudly. Hearing the donkey bray, the thief ran away, the master woke up and started beating the donkey for braying in the middle of the night for no reason.

Tao of Programming

Mon, 21 Jul 2014 00:00:00 +0000

The Silent Void

Thus spake the master programmer:

“When you have learned to snatch the error code from the trap frame, it will be time for you to leave.”

1.1

Something mysterious is formed, born in the silent void. Waiting alone and unmoving, it is at once still and yet in constant motion. It is the source of all programs. I do not know its name, so I will call it the Tao of Programming.

Unique Date

Sun, 27 Apr 2014 00:00:00 +0000

Fizz Buzz

Tue, 22 Apr 2014 00:00:00 +0000

Problem:

Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”.

f = lambda x: 'FizzBuzz' if not (x%5 or x%3) else 'Fizz' if not x%3 else 'Buzz' if not x%5 else str(x)
for x in range(100):
    print(f(x))

Fizz Buzz problem

Free Speech

Fri, 18 Apr 2014 00:00:00 +0000

Using timezone with datetime in python

Sat, 05 Apr 2014 00:00:00 +0000

>>> import pytz
>>> import datetime
>>> tz = pytz.timezone('Asia/Calcutta')
>>> tz
<DstTzInfo 'Asia/Calcutta' HMT+5:53:00 STD>
>>> t = tz.localize(datetime.datetime(2014, 4, 5, 6, 7, 8, 900))
>>> t
datetime.datetime(2014, 4, 5, 6, 7, 8, 900, tzinfo=<DstTzInfo 'Asia/Calcutta' IST+5:30:00 STD>)
>>> t.isoformat()
'2014-04-05T06:07:08.000900+05:30'

Reference: Python datetime object show wrong timezone offset

Toot

Sat, 08 Mar 2014 00:00:00 +0000

Flowchart

Wed, 25 Dec 2013 00:00:00 +0000

Translation table explaining the truth behind British politeness

Sun, 22 Dec 2013 00:00:00 +0000

What British Say	What the British Mean	What Foreigners Understand
I hear what you say	I disagree and do not want to discuss it further	He accepts my point of view
With the greatest respect	You are an idiot	He is listening to me
That’s not bad	That’s good	That’s poor
That is a very brave proposal	You are insane	He thinks I have courage
Quite good	A bit disappointing	Quite good
I would suggest	Do it or be prepared to justify yourself	Think about the idea, but do what you like
Oh, incidentally/ by the way	The primary purpose of our discussion is	That is not very important
I was a bit disappointed that	I am annoyed that	It doesn’t really matter
Very interesting	That is clearly nonsense	They are impressed
I’ll bear it in mind	I’ve forgotten it already	They will probably do it
I’m sure it’s my fault	It’s your fault	Why do they think it was their fault?
You must come for dinner	It’s not an invitation, I’m just being polite	I will get an invitation soon
I almost agree	I don’t agree at all	He’s not far from agreement
I only have a few minor comments	Please rewrite completely	He has found a few typos
Could we consider some other options	I don’t like your idea	They have not yet decided

By: Alice Philipson

String Theory

Fri, 22 Nov 2013 00:00:00 +0000

Converting mercurial repository to git

Sun, 17 Nov 2013 00:00:00 +0000

git clone git://repo.or.cz/fast-export.git
mkdir new_git_repo
cd new_git_repo
git init
/path/to/hg-fast-export.sh -r /path/to/hg_repo
git checkout HEAD

Researcher Translation

Sun, 17 Nov 2013 00:00:00 +0000

Estimation

Sat, 16 Nov 2013 00:00:00 +0000

Success

Sat, 16 Nov 2013 00:00:00 +0000

Server Problem

Sat, 05 Oct 2013 00:00:00 +0000

Explanation

Creating class in python without using class keyword

Wed, 02 Oct 2013 00:00:00 +0000

add2 = lambda x,y: x+y
sub2 = lambda x,y: x-y
mul2 = lambda x,y: x*y
# Second parameter is tuple, used for inheriting classes
# Third parameter is dict, used for defining variables and functions
myclass = type('myclass', (), {'var1': 10, 'add': add2, 'sub': sub2, 'mul': mul2})
myinstance = myclass()
print(myinstance.add(10,20))
print(myinstance.sub(10,20))
print(myinstance.mul(10,20))

Parental Trolling

Wed, 02 Oct 2013 00:00:00 +0000

Reversing the binary of the given number in python

Mon, 30 Sep 2013 00:00:00 +0000

>>> a=int(input('Enter base 10 natural number: '))
Enter base 10 natural number: 42
>>> b = bin(a)
>>> a = int(b[:2]+b[2:][::-1], 2)
>>> a
21

Campfire

Sat, 14 Sep 2013 00:00:00 +0000

GnuPG Key signing party

Mon, 02 Sep 2013 00:00:00 +0000

<key_id> will be signed by <your_key_id>.

Importing the key from server

[gpg2 –recv-keys <key_id>]{.title-ref}

Verify fingerprint

[gpg2 –fingerprint <key_id>]{.title-ref}

Signing the key

[gpg2 –sign-key <key_id>]{.title-ref}

Sending the key

[gpg2 –armor –output <key_id>.signed_by.<your_key_id>.asc –export <key_id>]{.title-ref}

<key_id>.signed_by.<your_key_id>.asc can be send by email or shared using any file sharing service.

Importing the signed key

[gpg2 –import <key_id>.signed_by.<your_key_id>.asc]{.title-ref}

Exporting the signed key to server

[gpg2 –send-keys <key_id>]{.title-ref}

What is Success?

Tue, 27 Aug 2013 00:00:00 +0000

At Age 4……Success is….not peeing in your pants.

At Age 6……Success is….finding your way home (from school)

At Age 12…..Success is….having friends

At Age 16/18..Success is….having a driver’s license

At Age 20…..Success is….having sex

At Age 35…..Success is….having money

At Age 45…..Success is….having money

At Age 55…..Success is….having money

At Age 60…..Success is….having sex

At Age 65…..Success is….keeping a driver’s license

At Age 70…..Success is….having friends

At Age 75…..Success is….finding your way home (from anywhere)

Corporate Policy

Sat, 24 Aug 2013 00:00:00 +0000

Start with a cage containing five monkeys. Inside the cage, hang a banana on a string and place a set of stairs under it. Before long, a monkey will go to the stairs and start to climb towards the banana. As soon as he touches the stairs, spray all of the other monkeys with cold water. After a while, another monkey makes an attempt with the same result; all the other monkeys are sprayed with cold water.

Relieve Boredom

Sat, 24 Aug 2013 00:00:00 +0000

To relieve the boredom, I remove a e-mail party invite from a user’s mail and post it under the senders username to alt.singles.with.severe.social.dysfunctions on news, and make a note in my diary to be there with my camcorder. Should be a blast!

Sandwich

Sat, 24 Aug 2013 00:00:00 +0000

Security

Fri, 23 Aug 2013 00:00:00 +0000

Mon, 01 Jan 0001 00:00:00 +0000

Invert display

xrandr -o inverted

Invert touchscreen

xinput –set-prop ‘WaveShare WS170120’ ‘Coordinate Transformation Matrix’ -1 0 1 0 -1 1 0 0 1

Useful URLS: https://wiki.ubuntu.com/X/InputCoordinateTransformation

Posts on Dhoomketu

Registration Data Access Protocol

Pros

Cons

Bootstrap URLs

DNS

RIRs

ccTLDs

Examples

Querying using web browser

Querying using CLI

Domain

ASN

IP Address

Entity

Garage Storage

Single Node Garage Setup

Download

Configuration

Create config file

systemd service

Koha Administration

Backup

Restore

Restore on new server

Match version

Create DB

Restore DB

Start instance

Stop instance

Restore

Upgrade

Rebuild index

Zebra

Elasticsearch

Restart services

Rate Limiting

Rate Limiting

Formula

Code

OpenDKIM with ED25519 keys

Generate keys

Update DNS records

Using nftables for dynamic rules

Create ruleset

File nftables.conf

Load ruleset

List ruleset

Add element

Delete element

Flush set

Backup

Restore

Delete

Table

Set

Rule

BOFH Excuses

HTTP Return codes

403 - Forbidden

Using ipset for dynamic rules

Create set

IPv4

IPv6

Create firewall rules

IPv4

IPv6

Block network

IPv4

IPv6

Unblock network

IPv4

IPv6

Flush set

IPv4

IPv6

Delete set

Backup

Restore

Delete firewall

File `nftables.conf`