August 14, 2019

7791 words 37 mins read

trimstray/the-book-of-secret-knowledge

trimstray/the-book-of-secret-knowledge

A collection of inspiring lists, manuals, cheatsheets, blogs, hacks, one-liners, cli/web tools and more.
repo name trimstray/the-book-of-secret-knowledge
repo link https://github.com/trimstray/the-book-of-secret-knowledge
homepage
language
size (curr.) 1517 kB
stars (curr.) 31264
created 2018-06-23
license MIT License

:notebook_with_decorative_cover:  What is it?

This repository is a collection of various materials and tools that I use every day in my work. It contains a lot of useful information gathered in one piece. It is an invaluable source of knowledge for me that I often look back on.

:restroom:  For whom?

For everyone, really. Here everyone can find their favourite tastes. But to be perfectly honest, it is aimed towards System and Network administrators, DevOps, Pentesters, and Security Researchers.

:information_source:  Contributing

If you find something which doesn’t make sense, or something doesn’t seem right, please make a pull request and please add valid and well-reasoned explanations about your changes or comments.

A few simple rules for this project:

  • inviting and clear
  • not tiring
  • useful

These below rules may be better:

  • easy to contribute to (Markdown + HTML …)
  • easy to find (simple TOC, maybe it’s worth extending them?)

Url marked * is temporary unavailable. Please don’t delete it without confirming that it has permanently expired.

Before adding a pull request, please see the contributing guidelines. You should also remember about this:

+ This repository is not meant to contain everything but only good quality stuff.

All suggestions/PR are welcome!

Code Contributors

This project exists thanks to all the people who contribute.

Financial Contributors

Individuals

Become a financial contributor and help us sustain our community » contribute.

Organizations

Support this project with your organization. Your logo will show up here with a link to your website » contribute.

:gift_heart:  Support

If this project is useful and important for you or if you really like the-book-of-secret-knowledge, you can bring positive energy by giving some good words or supporting this project. Thank you!

:newspaper:  RSS Feed & Updates

GitHub exposes an RSS/Atom feed of the commits, which may also be useful if you want to be kept informed about all changes.

:ballot_box_with_check:  ToDo

  • Add new stuff…
  • Add useful shell functions
  • Add one-liners for collection tools (eg. CLI Tools)
  • Sort order in lists

New items are also added on a regular basis.

:anger:  Table of Contents

Only main chapters:

:trident:  The Book of Secret Knowledge (Chapters)

CLI Tools  [TOC]

:black_small_square: Shells
:black_small_square: Shell plugins
:black_small_square: Managers
:black_small_square: Text editors
:black_small_square: Files and directories
:black_small_square: Network
:black_small_square: Network (DNS)
:black_small_square: Network (HTTP)
:black_small_square: SSL
:black_small_square: Security
:black_small_square: Auditing Tools
:black_small_square: System Diagnostics/Debuggers
:black_small_square: Log Analyzers
:black_small_square: Databases
:black_small_square: TOR
:black_small_square: Messengers/IRC Clients
:black_small_square: Other

GUI Tools  [TOC]

:black_small_square: Terminal emulators
:black_small_square: Network
:black_small_square: Browsers
:black_small_square: Password Managers
:black_small_square: Messengers/IRC Clients
:black_small_square: Messengers (end-to-end encryption)
:black_small_square: Text editors

Web Tools  [TOC]

:black_small_square: Browsers
:black_small_square: SSL/Security
:black_small_square: HTTP Headers & Web Linters
:black_small_square: DNS
:black_small_square: Mail
:black_small_square: Encoders/Decoders and Regex testing
:black_small_square: Net-tools
:black_small_square: Privacy
:black_small_square: Code parsers/playgrounds
:black_small_square: Performance
:black_small_square: Mass scanners (search engines)
:black_small_square: Generators
:black_small_square: Passwords
:black_small_square: CVE/Exploits databases
:black_small_square: Mobile apps scanners
:black_small_square: Private Search Engines
:black_small_square: Secure Webmail Providers
:black_small_square: Crypto
:black_small_square: PGP Keyservers

Systems/Services  [TOC]

:black_small_square: Operating Systems
:black_small_square: HTTP(s) Services
:black_small_square: DNS Services
:black_small_square: Other Services
:black_small_square: Security/hardening

Networks  [TOC]

:black_small_square: Tools
:black_small_square: Labs
:black_small_square: Other

Containers/Orchestration  [TOC]

:black_small_square: CLI Tools
:black_small_square: Web Tools
:black_small_square: Manuals/Tutorials/Best Practices

Manuals/Howtos/Tutorials  [TOC]

:black_small_square: Shell/Command line
:black_small_square: Text Editors
:black_small_square: Python
:black_small_square: Sed & Awk & Other
:black_small_square: *nix & Network
:black_small_square: Microsoft
:black_small_square: Large-scale systems
:black_small_square: System hardening
:black_small_square: Security & Privacy
:black_small_square: Web Apps
:black_small_square: All-in-one
:black_small_square: Other

Inspiring Lists  [TOC]

:black_small_square: SysOps/DevOps
:black_small_square: Developers
:black_small_square: Security/Pentesting
:black_small_square: Other

Blogs/Podcasts/Videos  [TOC]

:black_small_square: SysOps/DevOps
:black_small_square: Developers
:black_small_square: Geeky Persons
:black_small_square: Geeky Blogs
:black_small_square: Geeky Vendor Blogs
:black_small_square: Geeky Cybersecurity Podcasts
:black_small_square: Geeky Cybersecurity Video Blogs
:black_small_square: Best Personal Twitter Accounts
:black_small_square: Best Commercial Twitter Accounts
:black_small_square: A piece of history
:black_small_square: Other

Hacking/Penetration Testing  [TOC]

:black_small_square: Pentesters arsenal tools
:black_small_square: Pentests bookmarks collection
:black_small_square: Backdoors/exploits
:black_small_square: Wordlists and Weak passwords
:black_small_square: Bounty platforms
:black_small_square: Web Training Apps (local installation)
:black_small_square: Labs (ethical hacking platforms/trainings/CTFs)
:black_small_square: CTF platforms
:black_small_square: Other resources

Your daily knowledge and news  [TOC]

:black_small_square: RSS Readers
:black_small_square: IRC Channels
:black_small_square: Security
:black_small_square: Other/All-in-one

Other Cheat Sheets  [TOC]

Build your own DNS Servers
Build your own Certificate Authority
Build your own System/Virtual Machine
DNS Servers list (privacy)
IP URL
84.200.69.80 dns.watch
94.247.43.254 opennic.org
64.6.64.6 verisign.com
89.233.43.71 censurfridns.dk
1.1.1.1 cloudflare.com
94.130.110.185 dnsprivacy.at
TOP Browser extensions
Extension name Description
IPvFoo Display the server IP address and HTTPS information across all page elements.
FoxyProxy Simplifies configuring browsers to access proxy-servers.
HTTPS Everywhere Automatically use HTTPS security on many sites.
uMatrix Point & click to forbid/allow any class of requests made by your browser.
uBlock Origin An efficient blocker: easy on memory and CPU footprint.
Session Buddy Manage browser tabs and bookmarks with ease.
SuperSorter Sort bookmarks recursively, delete duplicates, merge folders and more.
Clear Cache Clear your cache and browsing data.
d3coder Encoding/Decoding plugin for various types of encoding.
Web Developer Adds a toolbar button with various web developer tools.
ThreatPinch Lookup Add threat intelligence hover tool tips.
TOP Burp extensions
Extension name Description
Autorize Automatically detects authorization enforcement.
Reflection An efficient blocker: easy on memory and CPU footprint.
Logger++ Logs requests and responses for all Burp tools in a sortable table.
Bypass WAF Adds headers useful for bypassing some WAF devices.
JSON Beautifier Beautifies JSON content in the HTTP message viewer.
JSON Web Tokens Enables Burp to decode and manipulate JSON web tokens.
CSP Auditor Displays CSP headers for responses, and passively reports CSP weaknesses.
CSP-Bypass Passively scans for CSP headers that contain known bypasses.
Hackvertor Converts data using a tag-based configuration to apply various encoding.
Active Scan++ Extends Burp’s active and passive scanning capabilities.
HTML5 Auditor Scans for usage of risky HTML5 features.
Software Vulnerability Scanner Software vulnerability scanner based on Vulners.com audit API.
Hack Mozilla Firefox addressbar

In Firefox’s addressbar, you can limit results by typing special characters before or after your term:

  • ^ - for matches in your browsing history
  • * - for matches in your bookmarks.
  • % - for matches in your currently open tabs.
  • # - for matches in page titles.
  • @ - for matches in web addresses.
Bypass WAFs by Shortening IP Address (by 0xInfection)

IP addresses can be shortened by dropping the zeroes:

http://1.0.0.1 → http://1.1
http://127.0.0.1 → http://127.1
http://192.168.0.1 → http://192.168.1

http://0xC0A80001 or http://3232235521 → 192.168.0.1
http://192.168.257 → 192.168.1.1
http://192.168.516 → 192.168.2.4

This bypasses WAF filters for SSRF, open-redirect, etc where any IP as input gets blacklisted.

For more information please see How to Obscure Any URL and Magic IP Address Shortcuts.

One-liners  [TOC]

Table of Contents
Tool: terminal
Reload shell without exit
exec $SHELL -l
Close shell keeping all subprocess running
disown -a && exit
Exit without saving shell history
kill -9 $$
unset HISTFILE && exit
Perform a branching conditional
true && echo success
false || echo failed
Pipe stdout and stderr to separate commands
some_command > >(/bin/cmd_for_stdout) 2> >(/bin/cmd_for_stderr)
Redirect stdout and stderr each to separate files and print both to the screen
(some_command 2>&1 1>&3 | tee errorlog ) 3>&1 1>&2 | tee stdoutlog
List of commands you use most often
history | \
awk '{CMD[$2]++;count++;}END { for (a in CMD)print CMD[a] " " CMD[a]/count*100 "% " a;}' | \
grep -v "./" | \
column -c3 -s " " -t | \
sort -nr | nl |  head -n 20
Sterilize bash history
function sterile() {

  history | awk '$2 != "history" { $1=""; print $0 }' | egrep -vi "\
curl\b+.*(-E|--cert)\b+.*\b*|\
curl\b+.*--pass\b+.*\b*|\
curl\b+.*(-U|--proxy-user).*:.*\b*|\
curl\b+.*(-u|--user).*:.*\b*
.*(-H|--header).*(token|auth.*)\b+.*|\
wget\b+.*--.*password\b+.*\b*|\
http.?://.+:.+@.*\
" > $HOME/histbuff; history -r $HOME/histbuff;

}

export PROMPT_COMMAND="sterile"

Look also: A naive utility to censor credentials in command history.

Quickly backup a file
cp filename{,.orig}
Empty a file (truncate to 0 size)
>filename
Delete all files in a folder that don’t match a certain file extension
rm !(*.foo|*.bar|*.baz)
Pass multi-line string to a file
# cat  >filename ... - overwrite the file
# cat >>filename ... - append to a file
cat > filename << __EOF__
data data data
__EOF__
Edit a file on a remote host using vim
vim scp://user@host//etc/fstab
Create a directory and change into it at the same time
mkd() { mkdir -p "$@" && cd "$@"; }
Convert uppercase files to lowercase files
rename 'y/A-Z/a-z/' *

printf "%`tput cols`s" | tr ' ' '#'
Show shell history without line numbers
history | cut -c 8-
fc -l -n 1 | sed 's/^\s*//'
Run command(s) after exit session
cat > /etc/profile << __EOF__
_after_logout() {

  username=$(whoami)

  for _pid in $(ps afx | grep sshd | grep "$username" | awk '{print $1}') ; do

    kill -9 $_pid

  done

}
trap _after_logout EXIT
__EOF__
Generate a sequence of numbers
for ((i=1; i<=10; i+=2)) ; do echo $i ; done
# alternative: seq 1 2 10

for ((i=5; i<=10; ++i)) ; do printf '%02d\n' $i ; done
# alternative: seq -w 5 10

for i in {1..10} ; do echo $i ; done
Simple Bash filewatching
unset MAIL; export MAILCHECK=1; export MAILPATH='$FILE_TO_WATCH?$MESSAGE'
Tool: busybox
Static HTTP web server
busybox httpd -p $PORT -h $HOME [-c httpd.conf]
Tool: mount
Mount a temporary ram partition
mount -t tmpfs tmpfs /mnt -o size=64M
  • -t - filesystem type
  • -o - mount options
Remount a filesystem as read/write
mount -o remount,rw /
Tool: fuser
Show which processes use the files/directories
fuser /var/log/daemon.log
fuser -v /home/supervisor
Kills a process that is locking a file
fuser -ki filename
  • -i - interactive option
Kills a process that is locking a file with specific signal
fuser -k -HUP filename
  • --list-signals - list available signal names
Show what PID is listening on specific port
fuser -v 53/udp
Show all processes using the named filesystems or block device
fuser -mv /var/www
Tool: lsof
Show process that use internet connection at the moment
lsof -P -i -n
Show process that use specific port number
lsof -i tcp:443
Lists all listening ports together with the PID of the associated process
lsof -Pan -i tcp -i udp
List all open ports and their owning executables
lsof -i -P | grep -i "listen"
Show all open ports
lsof -Pnl -i
Show open ports (LISTEN)
lsof -Pni4 | grep LISTEN | column -t
List all files opened by a particular command
lsof -c "process"
View user activity per directory
lsof -u username -a +D /etc
Show 10 largest open files
lsof / | \
awk '{ if($7 > 1048576) print $7/1048576 "MB" " " $9 " " $1 }' | \
sort -n -u | tail | column -t
Show current working directory of a process
lsof -p <PID> | grep cwd
Tool: ps
Show a 4-way scrollable process tree with full details
ps awwfux | less -S
Processes per user counter
ps hax -o user | sort | uniq -c | sort -r
Show all processes by name with main header
ps -lfC nginx
Tool: find
Find files that have been modified on your system in the past 60 minutes
find / -mmin 60 -type f
Find all files larger than 20M
find / -type f -size +20M
Find duplicate files (based on MD5 hash)
find -type f -exec md5sum '{}' ';' | sort | uniq --all-repeated=separate -w 33
Change permission only for files
cd /var/www/site && find . -type f -exec chmod 766 {} \;
cd /var/www/site && find . -type f -exec chmod 664 {} +
Change permission only for directories
cd /var/www/site && find . -type d -exec chmod g+x {} \;
cd /var/www/site && find . -type d -exec chmod g+rwx {} +
Find files and directories for specific user/group
# User:
find . -user <username> -print
find /etc -type f -user <username> -name "*.conf"

# Group:
find /opt -group <group>
find /etc -type f -group <group> -iname "*.conf"
Find files and directories for all without specific user/group
# User:
find . \! -user <username> -print

# Group:
find . \! -group <group>
Looking for files/directories that only have certain permission
# User
find . -user <username> -perm -u+rw # -rw-r--r--
find /home -user $(whoami) -perm 777 # -rwxrwxrwx

# Group:
find /home -type d -group <group> -perm 755 # -rwxr-xr-x
Delete older files than 60 days
find . -type f -mtime +60 -delete
Recursively remove all empty sub-directories from a directory
find . -depth  -type d  -empty -exec rmdir {} \;

find </path/to/dir> -xdev -samefile filename
Recursively find the latest modified files
find . -type f -exec stat --format '%Y :%y %n' "{}" \; | sort -nr | cut -d: -f2- | head
Recursively find/replace of a string with sed
find . -not -path '*/\.git*' -type f -print0 | xargs -0 sed -i 's/foo/bar/g'
Recursively find/replace of a string in directories and file names
find . -depth -name '*test*' -execdir bash -c 'mv -v "$1" "${1//foo/bar}"' _ {} \;
Recursively find suid executables
find / \( -perm -4000 -o -perm -2000 \) -type f -exec ls -la {} \;
Tool: top
Use top to monitor only all processes with the specific string
top -p $(pgrep -d , <str>)
  • <str> - process containing string (eg. nginx, worker)
Tool: vmstat
Show current system utilization (fields in kilobytes)
vmstat 2 20 -t -w
  • 2 - number of times with a defined time interval (delay)
  • 20 - each execution of the command (count)
  • -t - show timestamp
  • -w - wide output
  • -S M - output of the fields in megabytes instead of kilobytes
Show current system utilization will get refreshed every 5 seconds
vmstat 5 -w
Display report a summary of disk operations
vmstat -D
Display report of event counters and memory stats
vmstat -s
Display report about kernel objects stored in slab layer cache
vmstat -m
Tool: iostat
Show information about the CPU usage, and I/O statistics about all the partitions
iostat 2 10 -t -m
  • 2 - number of times with a defined time interval (delay)
  • 10 - each execution of the command (count)
  • -t - show timestamp
  • -m - fields in megabytes (-k - in kilobytes, default)
Show information only about the CPU utilization
iostat 2 10 -t -m -c
Show information only about the disk utilization
iostat 2 10 -t -m -d
Show information only about the LVM utilization
iostat -N
Tool: strace
Track with child processes
# 1)
strace -f -p $(pidof glusterfsd)

# 2)
strace -f $(pidof php-fpm | sed 's/\([0-9]*\)/\-p \1/g')
Track process with 30 seconds limit
timeout 30 strace $(< /var/run/zabbix/zabbix_agentd.pid)
Track processes and redirect output to a file
ps auxw | grep '[a]pache' | awk '{print " -p " $2}' | \
xargs strace -o /tmp/strace-apache-proc.out
Track with print time spent in each syscall and limit length of print strings
ps auxw | grep '[i]init_policy' | awk '{print " -p " $2}' | \
xargs strace -f -e trace=network -T -s 10000
Track the open request of a network port
strace -f -e trace=bind nc -l 80
Track the open request of a network port (show TCP/UDP)
strace -f -e trace=network nc -lu 80
Tool: kill
Kill a process running on port
kill -9 $(lsof -i :<port> | awk '{l=$2} END {print l}')
Tool: diff
Compare two directory trees
diff <(cd directory1 && find | sort) <(cd directory2 && find | sort)
Compare output of two commands
diff <(cat /etc/passwd) <(cut -f2 /etc/passwd)
Tool: vimdiff
Highlight the exact differences, based on characters and words
vimdiff file1 file2
Compare two JSON files
vimdiff <(jq -S . A.json) <(jq -S . B.json)
Compare Hex dump
d(){ vimdiff <(f $1) <(f $2);};f(){ hexdump -C $1|cut -d' ' -f3-|tr -s ' ';}; d ~/bin1 ~/bin2
diffchar

Save diffchar @ ~/.vim/plugins

Click F7 to switch between diff modes

Usefull vimdiff commands:

  • qa to exit all windows
  • :vertical resize 70 to resize window
  • set window width Ctrl+W [N columns]+(Shift+)<\>
Tool: tail
Annotate tail -f with timestamps
tail -f file | while read ; do echo "$(date +%T.%N) $REPLY" ; done
Analyse an Apache access log for the most common IP addresses
tail -10000 access_log | awk '{print $1}' | sort | uniq -c | sort -n | tail
Analyse web server log and show only 5xx http codes
tail -n 100 -f /path/to/logfile | grep "HTTP/[1-2].[0-1]\" [5]"
Tool: tar
System backup with exclude specific directories
cd /
tar -czvpf /mnt/system$(date +%d%m%Y%s).tgz --directory=/ \
--exclude=proc/* --exclude=sys/* --exclude=dev/* --exclude=mnt/* .
System backup with exclude specific directories (pigz)
cd /
tar cvpf /backup/snapshot-$(date +%d%m%Y%s).tgz --directory=/ \
--exclude=proc/* --exclude=sys/* --exclude=dev/* \
--exclude=mnt/* --exclude=tmp/* --use-compress-program=pigz .
Tool: dump
System backup to file
dump -y -u -f /backup/system$(date +%d%m%Y%s).lzo /
Restore system from lzo file
cd /
restore -rf /backup/system$(date +%d%m%Y%s).lzo
Tool: cpulimit
Limit the cpu usage of a process
cpulimit -p pid -l 50
Tool: pwdx
Show current working directory of a process
pwdx <pid>
Tool: taskset
Start a command on only one CPU core
taskset -c 0 <command>
Tool: tr
Show directories in the PATH, one per line
tr : '\n' <<<$PATH
Tool: chmod
Remove executable bit from all files in the current directory
chmod -R -x+X *
Restore permission for /bin/chmod
# 1:
cp /bin/ls chmod.01
cp /bin/chmod chmod.01
./chmod.01 700 file

# 2:
/bin/busybox chmod 0700 /bin/chmod

# 3:
setfacl --set u::rwx,g::---,o::--- /bin/chmod
Tool: who
Find last reboot time
who -b
Detect a user sudo-su’d into the current shell
[[ $(who -m | awk '{ print $1 }') == $(whoami) ]] || echo "You are su-ed to $(whoami)"
Tool: last
Was the last reboot a panic?
(last -x -f $(ls -1t /var/log/wtmp* | head -2 | tail -1); last -x -f /var/log/wtmp) | \
grep -A1 reboot | head -2 | grep -q shutdown && echo "Expected reboot" || echo "Panic reboot"
Tool: screen
Start screen in detached mode
screen -d -m <command>
Attach to an existing screen session
screen -r -d <pid>
Tool: script
Record and replay terminal session
### Record session
# 1)
script -t 2>~/session.time -a ~/session.log

# 2)
script --timing=session.time session.log

### Replay session
scriptreplay --timing=session.time session.log
Tool: du
Show 20 biggest directories with ‘K M G’
du | \
sort -r -n | \
awk '{split("K M G",v); s=1; while($1>1024){$1/=1024; s++} print int($1)" "v[s]"\t"$2}' | \
head -n 20
Tool: inotifywait
Init tool everytime a file in a directory is modified
while true ; do inotifywait -r -e MODIFY dir/ && ls dir/ ; done;
Tool: openssl
Testing connection to the remote host
echo | openssl s_client -connect google.com:443 -showcerts
Testing connection to the remote host (debug mode)
echo | openssl s_client -connect google.com:443 -showcerts -tlsextdebug -status
Testing connection to the remote host (with SNI support)
echo | openssl s_client -showcerts -servername google.com -connect google.com:443
Testing connection to the remote host with specific ssl version
openssl s_client -tls1_2 -connect google.com:443
Testing connection to the remote host with specific ssl cipher
openssl s_client -cipher 'AES128-SHA' -connect google.com:443
Verify 0-RTT
_host="example.com"

cat > req.in << __EOF__
HEAD / HTTP/1.1
Host: $_host
Connection: close
__EOF__

openssl s_client -connect ${_host}:443 -tls1_3 -sess_out session.pem -ign_eof < req.in
openssl s_client -connect ${_host}:443 -tls1_3 -sess_in session.pem -early_data req.in
Generate private key without passphrase
# _len: 2048, 4096
( _fd="private.key" ; _len="4096" ; \
openssl genrsa -out ${_fd} ${_len} )
Generate private key with passphrase
# _ciph: des3, aes128, aes256
# _len: 2048, 4096
( _ciph="aes128" ; _fd="private.key" ; _len="4096" ; \
openssl genrsa -${_ciph} -out ${_fd} ${_len} )
Remove passphrase from private key
( _fd="private.key" ; _fd_unp="private_unp.key" ; \
openssl rsa -in ${_fd} -out ${_fd_unp} )
Encrypt existing private key with a passphrase
# _ciph: des3, aes128, aes256
( _ciph="aes128" ; _fd="private.key" ; _fd_pass="private_pass.key" ; \
openssl rsa -${_ciph} -in ${_fd} -out ${_fd_pass}
Check private key
( _fd="private.key" ; \
openssl rsa -check -in ${_fd} )
Get public key from private key
( _fd="private.key" ; _fd_pub="public.key" ; \
openssl rsa -pubout -in ${_fd} -out ${_fd_pub} )
Generate private key and CSR
( _fd="private.key" ; _fd_csr="request.csr" ; _len="4096" ; \
openssl req -out ${_fd_csr} -new -newkey rsa:${_len} -nodes -keyout ${_fd} )
Generate CSR
( _fd="private.key" ; _fd_csr="request.csr" ; \
openssl req -out ${_fd_csr} -new -key ${_fd} )
Generate CSR (metadata from existing certificate)

Where private.key is the existing private key. As you can see you do not generate this CSR from your certificate (public key). Also you do not generate the “same” CSR, just a new one to request a new certificate.

( _fd="private.key" ; _fd_csr="request.csr" ; _fd_crt="cert.crt" ; \
openssl x509 -x509toreq -in ${_fd_crt} -out ${_fd_csr} -signkey ${_fd} )
Generate CSR with -config param
( _fd="private.key" ; _fd_csr="request.csr" ; \
openssl req -new -sha256 -key ${_fd} -out ${_fd_csr} \
-config <(
cat << __EOF__
[req]
default_bits        = 2048
default_md          = sha256
prompt              = no
distinguished_name  = dn
req_extensions      = req_ext

[ dn ]
C   = "<two-letter ISO abbreviation for your country>"
ST  = "<state or province where your organisation is legally located>"
L   = "<city where your organisation is legally located>"
O   = "<legal name of your organisation>"
OU  = "<section of the organisation>"
CN  = "<fully qualified domain name>"

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = <fully qualified domain name>
DNS.2 = <next domain>
DNS.3 = <next domain>
__EOF__
))

Other values in [ dn ]:

Look at this great explanation: How to create multidomain certificates using config files

countryName            = "DE"                     # C=
stateOrProvinceName    = "Hessen"                 # ST=
localityName           = "Keller"                 # L=
postalCode             = "424242"                 # L/postalcode=
streetAddress          = "Crater 1621"            # L/street=
organizationName       = "apfelboymschule"        # O=
organizationalUnitName = "IT Department"          # OU=
commonName             = "example.com"            # CN=
emailAddress           = "webmaster@example.com"  # CN/emailAddress=
List available EC curves
openssl ecparam -list_curves
Generate ECDSA private key
# _curve: prime256v1, secp521r1, secp384r1
( _fd="private.key" ; _curve="prime256v1" ; \
openssl ecparam -out ${_fd} -name ${_curve} -genkey )

# _curve: X25519
( _fd="private.key" ; _curve="x25519" ; \
openssl genpkey -algorithm ${_curve} -out ${_fd} )

( _fd="private.key" ; \
openssl ec -in ${_fd} -noout -text )

# For x25519 only extracting public key
( _fd="private.key" ; _fd_pub="public.key" ; \
openssl pkey -in ${_fd} -pubout -out ${_fd_pub} )
Generate private key with CSR (ECC)
# _curve: prime256v1, secp521r1, secp384r1
( _fd="domain.com.key" ; _fd_csr="domain.com.csr" ; _curve="prime256v1" ; \
openssl ecparam -out ${_fd} -name ${_curve} -genkey ; \
openssl req -new -key ${_fd} -out ${_fd_csr} -sha256 )
Generate self-signed certificate
# _len: 2048, 4096
( _fd="domain.key" ; _fd_out="domain.crt" ; _len="4096" ; _days="365" ; \
openssl req -newkey rsa:${_len} -nodes \
-keyout ${_fd} -x509 -days ${_days} -out ${_fd_out} )
Generate self-signed certificate from existing private key
# _len: 2048, 4096
( _fd="domain.key" ; _fd_out="domain.crt" ; _days="365" ; \
openssl req -key ${_fd} -nodes \
-x509 -days ${_days} -out ${_fd_out} )
Generate self-signed certificate from existing private key and csr
# _len: 2048, 4096
( _fd="domain.key" ; _fd_csr="domain.csr" ; _fd_out="domain.crt" ; _days="365" ; \
openssl x509 -signkey ${_fd} -nodes \
-in ${_fd_csr} -req -days ${_days} -out ${_fd_out} )
Generate DH public parameters
( _dh_size="2048" ; \
openssl dhparam -out /etc/nginx/ssl/dhparam_${_dh_size}.pem "$_dh_size" )
Display DH public parameters
openssl pkeyparam -in dhparam.pem -text
Extract private key from pfx
( _fd_pfx="cert.pfx" ; _fd_key="key.pem" ; \
openssl pkcs12 -in ${_fd_pfx} -nocerts -nodes -out ${_fd_key} )
Extract private key and certs from pfx
( _fd_pfx="cert.pfx" ; _fd_pem="key_certs.pem" ; \
openssl pkcs12 -in ${_fd_pfx} -nodes -out ${_fd_pem} )
Convert DER to PEM
( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
openssl x509 -in ${_fd_der} -inform der -outform pem -out ${_fd_pem} )
Convert PEM to DER
( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
openssl x509 -in ${_fd_pem} -outform der -out ${_fd_der} )
Verification of the private key
( _fd="private.key" ; \
openssl rsa -noout -text -in ${_fd} )
Verification of the public key
# 1)
( _fd="public.key" ; \
openssl pkey -noout -text -pubin -in ${_fd} )

# 2)
( _fd="private.key" ; \
openssl rsa -inform PEM -noout -in ${_fd} &> /dev/null ; \
if [ $? = 0 ] ; then echo -en "OK\n" ; fi )
Verification of the certificate
( _fd="certificate.crt" ; # format: pem, cer, crt \
openssl x509 -noout -text -in ${_fd} )
Verification of the CSR
( _fd_csr="request.csr" ; \
openssl req -text -noout -in ${_fd_csr} )
Check whether the private key and the certificate match
(openssl rsa -noout -modulus -in private.key | openssl md5 ; \
openssl x509 -noout -modulus -in certificate.crt | openssl md5) | uniq
Check whether the private key and the CSR match
(openssl rsa -noout -modulus -in private.key | openssl md5 ; \
openssl req -noout -modulus -in request.csr | openssl md5) | uniq
Tool: secure-delete
Secure delete with shred
shred -vfuz -n 10 file
shred --verbose --random-source=/dev/urandom -n 1 /dev/sda
Secure delete with scrub
scrub -p dod /dev/sda
scrub -p dod -r file
Secure delete with badblocks
badblocks -s -w -t random -v /dev/sda
badblocks -c 10240 -s -w -t random -v /dev/sda
Secure delete with secure-delete
srm -vz /tmp/file
sfill -vz /local
sdmem -v
swapoff /dev/sda5 && sswap -vz /dev/sda5
Tool: dd
Show dd status every so often
dd <dd_params> status=progress
watch --interval 5 killall -USR1 dd
Redirect output to a file with dd
echo "string" | dd of=filename
Tool: gpg
Export public key
gpg --export --armor "<username>" > username.pkey
  • --export - export all keys from all keyrings or specific key
  • -a|--armor - create ASCII armored output
Encrypt file
gpg -e -r "<username>" dump.sql
  • -e|--encrypt - encrypt data
  • -r|--recipient - encrypt for specific
Decrypt file
gpg -o dump.sql -d dump.sql.gpg
  • -o|--output - use as output file
  • -d|--decrypt - decrypt data (default)
Search recipient
gpg --keyserver hkp://keyserver.ubuntu.com --search-keys "<username>"
  • --keyserver - set specific key server
  • --search-keys - search for keys on a key server
List all of the packets in an encrypted file
gpg --batch --list-packets archive.gpg
gpg2 --batch --list-packets archive.gpg
Tool: system-other
Reboot system from init
exec /sbin/init 6
Init system from single user mode
exec /sbin/init
Show current working directory of a process
readlink -f /proc/<PID>/cwd
Show actual pathname of the executed command
readlink -f /proc/<PID>/exe
Tool: curl
curl -Iks https://www.google.com
  • -I - show response headers only
  • -k - insecure connection when using ssl
  • -s - silent mode (not display body)
curl -Iks --location -X GET -A "x-agent" https://www.google.com
  • --location - follow redirects
  • -X - set method
  • -A - set user-agent
curl -Iks --location -X GET -A "x-agent" --proxy http://127.0.0.1:16379 https://www.google.com
  • --proxy [socks5://|http://] - set proxy server
curl -o file.pdf -C - https://example.com/Aiju2goo0Ja2.pdf
  • -o - write output to file
  • -C - resume the transfer
Find your external IP address (external services)
curl ipinfo.io
curl ipinfo.io/ip
curl icanhazip.com
curl ifconfig.me/ip ; echo
Repeat URL request
# URL sequence substitution with a dummy query string:
curl -ks https://example.com/?[1-20]

# With shell 'for' loop:
for i in {1..20} ; do curl -ks https://example.com/ ; done
Check DNS and HTTP trace with headers for specific domains
### Set domains and external dns servers.
_domain_list=(google.com) ; _dns_list=("8.8.8.8" "1.1.1.1")

for _domain in "${_domain_list[@]}" ; do

  printf '=%.0s' {1..48}

  echo

  printf "[\\e[1;32m+\\e[m] resolve: %s\\n" "$_domain"

  for _dns in "${_dns_list[@]}" ; do

    # Resolve domain.
    host "${_domain}" "${_dns}"

    echo

  done

  for _proto in http https ; do

    printf "[\\e[1;32m+\\e[m] trace + headers: %s://%s\\n" "$_proto" "$_domain"

    # Get trace and http headers.
    curl -Iks -A "x-agent" --location "${_proto}://${_domain}"

    echo

  done

done

unset _domain_list _dns_list
Tool: httpie
http -p Hh https://www.google.com
  • -p - print request and response headers
    • H - request headers
    • B - request body
    • h - response headers
    • b - response body
http -p Hh https://www.google.com --follow --verify no
  • -F, --follow - follow redirects
  • --verify no - skip SSL verification
http -p Hh https://www.google.com --follow --verify no \
--proxy http:http://127.0.0.1:16379
  • --proxy [http:] - set proxy server
Tool: ssh
Escape Sequence
# Supported escape sequences:
~.  - terminate connection (and any multiplexed sessions)
~B  - send a BREAK to the remote system
~C  - open a command line
~R  - Request rekey (SSH protocol 2 only)
~^Z - suspend ssh
~#  - list forwarded connections
~&  - background ssh (when waiting for connections to terminate)
~?  - this message
~~  - send the escape character by typing it twice
Compare a remote file with a local file
ssh user@host cat /path/to/remotefile | diff /path/to/localfile -
SSH connection through host in the middle
ssh -t reachable_host ssh unreachable_host
Run command over SSH on remote host
cat > cmd.txt << __EOF__
cat /etc/hosts
__EOF__

ssh host -l user $(<cmd.txt)
Get public key from private key
ssh-keygen -y -f ~/.ssh/id_rsa
Get all fingerprints
ssh-keygen -l -f .ssh/known_hosts
SSH authentication with user password
ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no user@remote_host
SSH authentication with publickey
ssh -o PreferredAuthentications=publickey -o PubkeyAuthentication=yes -i id_rsa user@remote_host
Simple recording SSH session
function _ssh_sesslog() {

  _sesdir="<path/to/session/logs>"

  mkdir -p "${_sesdir}" && \
  ssh $@ 2>&1 | tee -a "${_sesdir}/$(date +%Y%m%d).log"

}

# Alias:
alias ssh='_ssh_sesslog'
Using Keychain for SSH logins
### Delete all of ssh-agent's keys.
function _scl() {

  /usr/bin/keychain --clear

}

### Add key to keychain.
function _scg() {

  /usr/bin/keychain /path/to/private-key
  source "$HOME/.keychain/$HOSTNAME-sh"

}
SSH login without processing any login scripts
ssh -tt user@host bash
SSH local port forwarding

Example 1:

# Forwarding our local 2250 port to nmap.org:443 from localhost through localhost
host1> ssh -L 2250:nmap.org:443 localhost

# Connect to the service:
host1> curl -Iks --location -X GET https://localhost:2250

Example 2:

# Forwarding our local 9051 port to db.d.x:5432 from localhost through node.d.y
host1> ssh -nNT -L 9051:db.d.x:5432 node.d.y

# Connect to the service:
host1> psql -U db_user -d db_dev -p 9051 -h localhost
  • -n - redirects stdin from /dev/null
  • -N - do not execute a remote command
  • -T - disable pseudo-terminal allocation
SSH remote port forwarding
# Forwarding our local 9051 port to db.d.x:5432 from host2 through node.d.y
host1> ssh -nNT -R 9051:db.d.x:5432 node.d.y

# Connect to the service:
host2> psql -U postgres -d postgres -p 8000 -h localhost
Tool: linux-dev
Testing remote connection to port
timeout 1 bash -c "</dev/<proto>/<host>/<port>" >/dev/null 2>&1 ; echo $?
  • <proto - set protocol (tcp/udp)
  • <host> - set remote host
  • <port> - set destination port
Read and write to TCP or UDP sockets with common bash tools
exec 5<>/dev/tcp/<host>/<port>; cat <&5 & cat >&5; exec 5>&-
Tool: tcpdump
Filter incoming (on interface) traffic (specific ip:port)
tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443
  • -n - don’t convert addresses (-nn will not resolve hostnames or ports)
  • -e - print the link-level headers
  • -i [iface|any] - set interface
  • -Q|-D [in|out|inout] - choose send/receive direction (-D - for old tcpdump versions)
  • host [ip|hostname] - set host, also [host not]
  • [and|or] - set logic
  • port [1-65535] - set port number, also [port not]
Filter incoming (on interface) traffic (specific ip:port) and write to a file
tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443 -c 5 -w tcpdump.pcap
  • -c [num] - capture only num number of packets
  • -w [filename] - write packets to file, -r [filename] - reading from file
Capture all ICMP packets
tcpdump -nei eth0 icmp
Check protocol used (TCP or UDP) for service
tcpdump -nei eth0 tcp port 22 -vv -X | egrep "TCP|UDP"
Display ASCII text (to parse the output using grep or other)
tcpdump -i eth0 -A -s0 port 443
Grab everything between two keywords
tcpdump -i eth0 port 80 -X | sed -n -e '/username/,/=ldap/ p'
Grab user and pass ever plain http
tcpdump -i eth0  port http -l -A | egrep -i \
'pass=|pwd=|log=|login=|user=|username=|pw=|passw=|passwd=|password=|pass:|user:|username:|password:|login:|pass |user ' \
--color=auto --line-buffered -B20
Extract HTTP User Agent from HTTP request header
tcpdump -ei eth0 -nn -A -s1500 -l | grep "User-Agent:"
Capture only HTTP GET and POST packets
tcpdump -ei eth0 -s 0 -A -vv \
'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420' or 'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354'

or simply:

tcpdump -ei eth0 -s 0 -v -n -l | egrep -i "POST /|GET /|Host:"
Rotate capture files
tcpdump -ei eth0 -w /tmp/capture-%H.pcap -G 3600 -C 200
  • -G <num> - pcap will be created every <num> seconds
  • -C <size> - close the current pcap and open a new one if is larger than <size>
Top hosts by packets
tcpdump -ei enp0s25 -nnn -t -c 200 | cut -f 1,2,3,4 -d '.' | sort | uniq -c | sort -nr | head -n 20
Excludes any RFC 1918 private address
tcpdump -nei eth0 'not (src net (10 or 172.16/12 or 192.168/16) and dst net (10 or 172.16/12 or 192.168/16))'
Tool: tcpick
Analyse packets in real-time
while true ; do tcpick -a -C -r dump.pcap ; sleep 2 ; clear ; done
Tool: ngrep
ngrep -d eth0 "www.domain.com" port 443
  • -d [iface|any] - set interface
  • [domain] - set hostname
  • port [1-65535] - set port number
ngrep -d eth0 "www.domain.com" src host 10.240.20.2 and port 443
  • (host [ip|hostname]) - filter by ip or hostname
  • (port [1-65535]) - filter by port number
ngrep -d eth0 -qt -O ngrep.pcap "www.domain.com" port 443
  • -q - quiet mode (only payloads)
  • -t - added timestamps
  • -O [filename] - save output to file, -I [filename] - reading from file
ngrep -d eth0 -qt 'HTTP' 'tcp'
  • HTTP - show http headers
  • tcp|udp - set protocol
  • [src|dst] host [ip|hostname] - set direction for specific node
ngrep -l -q -d eth0 -i "User-Agent: curl*"
  • -l - stdout line buffered
  • -i - case-insensitive search
Tool: hping3
hping3 -V -p 80 -s 5050 <scan_type> www.google.com
  • -V|--verbose - verbose mode
  • -p|--destport - set destination port
  • -s|--baseport - set source port
  • <scan_type> - set scan type
    • -F|--fin - set FIN flag, port open if no reply
    • -S|--syn - set SYN flag
    • -P|--push - set PUSH flag
    • -A|--ack - set ACK flag (use when ping is blocked, RST response back if the port is open)
    • -U|--urg - set URG flag
    • -Y|--ymas - set Y unused flag (0x80 - nullscan), port open if no reply
    • -M 0 -UPF - set TCP sequence number and scan type (URG+PUSH+FIN), port open if no reply
hping3 -V -c 1 -1 -C 8 www.google.com
  • -c [num] - packet count
  • -1 - set ICMP mode
  • -C|--icmptype [icmp-num] - set icmp type (default icmp-echo = 8)
hping3 -V -c 1000000 -d 120 -S -w 64 -p 80 --flood --rand-source <remote_host>
  • --flood - sent packets as fast as possible (don’t show replies)
  • --rand-source - random source address mode
  • -d --data - data size
  • -w|--win - winsize (default 64)
Tool: nmap
Ping scans the network
nmap -sP 192.168.0.0/24
Show only open ports
nmap -F --open 192.168.0.0/24
Full TCP port scan using with service version detection
nmap -p 1-65535 -sV -sS -T4 192.168.0.0/24
Nmap scan and pass output to Nikto
nmap -p80,443 192.168.0.0/24 -oG - | nikto.pl -h -
Recon specific ip:service with Nmap NSE scripts stack
# Set variables:
_hosts="192.168.250.10"
_ports="80,443"

# Set Nmap NSE scripts stack:
_nmap_nse_scripts="+dns-brute,\
                   +http-auth-finder,\
                   +http-chrono,\
                   +http-cookie-flags,\
                   +http-cors,\
                   +http-cross-domain-policy,\
                   +http-csrf,\
                   +http-dombased-xss,\
                   +http-enum,\
                   +http-errors,\
                   +http-git,\
                   +http-grep,\
                   +http-internal-ip-disclosure,\
                   +http-jsonp-detection,\
                   +http-malware-host,\
                   +http-methods,\
                   +http-passwd,\
                   +http-phpself-xss,\
                   +http-php-version,\
                   +http-robots.txt,\
                   +http-sitemap-generator,\
                   +http-shellshock,\
                   +http-stored-xss,\
                   +http-title,\
                   +http-unsafe-output-escaping,\
                   +http-useragent-tester,\
                   +http-vhosts,\
                   +http-waf-detect,\
                   +http-waf-fingerprint,\
                   +http-xssed,\
                   +traceroute-geolocation.nse,\
                   +ssl-enum-ciphers,\
                   +whois-domain,\
                   +whois-ip"

# Set Nmap NSE script params:
_nmap_nse_scripts_args="dns-brute.domain=${_hosts},http-cross-domain-policy.domain-lookup=true,"
_nmap_nse_scripts_args+="http-waf-detect.aggro,http-waf-detect.detectBodyChanges,"
_nmap_nse_scripts_args+="http-waf-fingerprint.intensive=1"

# Perform scan:
nmap --script="$_nmap_nse_scripts" --script-args="$_nmap_nse_scripts_args" -p "$_ports" "$_hosts"
Tool: netcat
nc -kl 5000
  • -l - listen for an incoming connection
  • -k - listening after client has disconnected
  • >filename.out - save receive data to file (optional)
nc 192.168.0.1 5051 < filename.in
  • < filename.in - send data to remote host
nc -vz 10.240.30.3 5000
  • -v - verbose output
  • -z - scan for listening daemons
nc -vzu 10.240.30.3 1-65535
  • -u - scan only udp ports
Transfer data file (archive)
server> nc -l 5000 | tar xzvfp -
client> tar czvfp - /path/to/dir | nc 10.240.30.3 5000
Launch remote shell
# 1)
server> nc -l 5000 -e /bin/bash
client> nc 10.240.30.3 5000

# 2)
server> rm -f /tmp/f; mkfifo /tmp/f
server> cat /tmp/f | /bin/bash -i 2>&1 | nc -l 127.0.0.1 5000 > /tmp/f
client> nc 10.240.30.3 5000
Simple file server
while true ; do nc -l 5000 | tar -xvf - ; done
Simple minimal HTTP Server
while true ; do nc -l -p 1500 -c 'echo -e "HTTP/1.1 200 OK\n\n $(date)"' ; done
Simple HTTP Server

Restarts web server after each request - remove while condition for only single connection.

cat > index.html << __EOF__
<!doctype html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <title></title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
    </head>
    <body>

    <p>

      Hello! It's a site.

    </p>

    </body>
</html>
__EOF__

server> while : ; do \
(echo -ne "HTTP/1.1 200 OK\r\nContent-Length: $(wc -c <index.html)\r\n\r\n" ; cat index.html;) | \
nc -l -p 5000 \
; done
  • -p - port number
Simple HTTP Proxy (single connection)
#!/usr/bin/env bash

if [[ $# != 2 ]] ; then
  printf "%s\\n" \
         "usage: ./nc-proxy listen-port bk_host:bk_port"
fi

_listen_port="$1"
_bk_host=$(echo "$2" | cut -d ":" -f1)
_bk_port=$(echo "$2" | cut -d ":" -f2)

printf "  lport: %s\\nbk_host: %s\\nbk_port: %s\\n\\n" \
       "$_listen_port" "$_bk_host" "$_bk_port"

_tmp=$(mktemp -d)
_back="$_tmp/pipe.back"
_sent="$_tmp/pipe.sent"
_recv="$_tmp/pipe.recv"

trap 'rm -rf "$_tmp"' EXIT

mkfifo -m 0600 "$_back" "$_sent" "$_recv"

sed "s/^/=> /" <"$_sent" &
sed "s/^/<=  /" <"$_recv" &

nc -l -p "$_listen_port" <"$_back" | \
tee "$_sent" | \
nc "$_bk_host" "$_bk_port" | \
tee "$_recv" >"$_back"

server> chmod +x nc-proxy && ./nc-proxy 8080 192.168.252.10:8000
  lport: 8080
bk_host: 192.168.252.10
bk_port: 8000

client> http -p h 10.240.30.3:8080
HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: max-age=31536000
Content-Length: 2748
Content-Type: text/html; charset=utf-8
Date: Sun, 01 Jul 2018 20:12:08 GMT
Last-Modified: Sun, 01 Apr 2018 21:53:37 GMT
Create a single-use TCP or UDP proxy
### TCP -> TCP
nc -l -p 2000 -c "nc [ip|hostname] 3000"

### TCP -> UDP
nc -l -p 2000 -c "nc -u [ip|hostname] 3000"

### UDP -> UDP
nc -l -u -p 2000 -c "nc -u [ip|hostname] 3000"

### UDP -> TCP
nc -l -u -p 2000 -c "nc [ip|hostname] 3000"
Tool: gnutls-cli
Testing connection to remote host (with SNI support)
gnutls-cli -p 443 google.com
Testing connection to remote host (without SNI support)
gnutls-cli --disable-sni -p 443 google.com
Tool: socat
Testing remote connection to port
socat - TCP4:10.240.30.3:22
  • - - standard input (STDIO)
  • TCP4:<params> - set tcp4 connection with specific params
    • [hostname|ip] - set hostname/ip
    • [1-65535] - set port number
Redirecting TCP-traffic to a UNIX domain socket under Linux
socat TCP-LISTEN:1234,bind=127.0.0.1,reuseaddr,fork,su=nobody,range=127.0.0.0/8 UNIX-CLIENT:/tmp/foo
  • TCP-LISTEN:<params> - set tcp listen with specific params
    • [1-65535] - set port number
    • bind=[hostname|ip] - set bind hostname/ip
    • reuseaddr - allows other sockets to bind to an address
    • fork - keeps the parent process attempting to produce more connections
    • su=nobody - set user
    • range=[ip-range] - ip range
  • UNIX-CLIENT:<params> - communicates with the specified peer socket
    • filename - define socket
Tool: p0f
Set iface in promiscuous mode and dump traffic to the log file
p0f -i enp0s25 -p -d -o /dump/enp0s25.log
  • -i - listen on the specified interface
  • -p - set interface in promiscuous mode
  • -d - fork into background
  • -o - output file
Tool: netstat
Graph # of connections for each hosts
netstat -an | awk '/ESTABLISHED/ { split($5,ip,":"); if (ip[1] !~ /^$/) print ip[1] }' | \
sort | uniq -c | awk '{ printf("%s\t%s\t",$2,$1) ; for (i = 0; i < $1; i++) {printf("*")}; print "" }'
Monitor open connections for specific port including listen, count and sort it per IP
watch "netstat -plan | grep :443 | awk {'print \$5'} | cut -d: -f 1 | sort | uniq -c | sort -nk 1"
Grab banners from local IPv4 listening ports
netstat -nlt | grep 'tcp ' | grep -Eo "[1-9][0-9]*" | xargs -I {} sh -c "echo "" | nc -v -n -w1 127.0.0.1 {}"
Tool: rsync
Rsync remote data as root using sudo
rsync --rsync-path 'sudo rsync' username@hostname:/path/to/dir/ /local/
Tool: host
Resolves the domain name (using external dns server)
host google.com 9.9.9.9
Checks the domain administrator (SOA record)
host -t soa google.com 9.9.9.9
Tool: dig
Resolves the domain name (short output)
dig google.com +short
Lookup NS record for specific domain
dig @9.9.9.9 google.com NS
Query only answer section
dig google.com +nocomments +noquestion +noauthority +noadditional +nostats
Query ALL DNS Records
dig google.com ANY +noall +answer
DNS Reverse Look-up
dig -x 172.217.16.14 +short
Tool: certbot
Generate multidomain certificate
certbot certonly -d example.com -d www.example.com
Generate wildcard certificate
certbot certonly --manual --preferred-challenges=dns -d example.com -d *.example.com
Generate certificate with 4096 bit private key
certbot certonly -d example.com -d www.example.com --rsa-key-size 4096
Tool: network-other
Get all subnets for specific AS (Autonomous system)
AS="AS32934"
whois -h whois.radb.net -- "-i origin ${AS}" | \
grep "^route:" | \
cut -d ":" -f2 | \
sed -e 's/^[ \t]//' | \
sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4 | \
cut -d ":" -f2 | \
sed -e 's/^[ \t]/allow /' | \
sed 's/$/;/' | \
sed 's/allow  */subnet -> /g'
Resolves domain name from dns.google.com with curl and jq
_dname="google.com" ; curl -s "https://dns.google.com/resolve?name=${_dname}&type=A" | jq .
Tool: git
Log alias for a decent view of your repo
# 1)
git log --oneline --decorate --graph --all

# 2)
git log --graph \
--pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' \
--abbrev-commit
Tool: python
Static HTTP web server
# Python 3.x
python3 -m http.server 8000 --bind 127.0.0.1

# Python 2.x
python -m SimpleHTTPServer 8000
Static HTTP web server with SSL support
# Python 3.x
from http.server import HTTPServer, BaseHTTPRequestHandler
import ssl

httpd = HTTPServer(('localhost', 4443), BaseHTTPRequestHandler)

httpd.socket = ssl.wrap_socket (httpd.socket,
        keyfile="path/to/key.pem",
        certfile='path/to/cert.pem', server_side=True)

httpd.serve_forever()

# Python 2.x
import BaseHTTPServer, SimpleHTTPServer
import ssl

httpd = BaseHTTPServer.HTTPServer(('localhost', 4443),
        SimpleHTTPServer.SimpleHTTPRequestHandler)

httpd.socket = ssl.wrap_socket (httpd.socket,
        keyfile="path/tp/key.pem",
        certfile='path/to/cert.pem', server_side=True)

httpd.serve_forever()
Encode base64
python -m base64 -e <<< "sample string"
Decode base64
python -m base64 -d <<< "dGhpcyBpcyBlbmNvZGVkCg=="
Tool: awk
Search for matching lines
# egrep foo
awk '/foo/' filename
Search non matching lines
# egrep -v foo
awk '!/foo/' filename

# egrep -n foo
awk '/foo/{print FNR,$0}' filename

awk '{print $NF}' filename
Find all the lines longer than 80 characters
awk 'length($0)>80{print FNR,$0}' filename

awk 'length < 80 filename

awk '1; { print "" }' filename

awk '{ print FNR "\t" $0 }' filename
awk '{ printf("%5d : %s\n", NR, $0) }' filename   # in a fancy manner

awk 'NF { $0=++a " :" $0 }; { print }' filename

awk '/foo/{i=5+1;}{if(i){i--; print;}}' filename
Print the lines starting at the line matching ‘server {’ until the line matching ‘}’
awk '/server {/,/}/' filename

awk -F' ' '{print "ip:\t" $2 "\n port:\t" $3' filename
Remove empty lines
awk 'NF > 0' filename

# alternative:
awk NF filename
Delete trailing white space (spaces, tabs)
awk '{sub(/[ \t]*$/, "");print}' filename
Delete leading white space
awk '{sub(/^[ \t]+/, ""); print}' filename
Remove duplicate consecutive lines
# uniq
awk 'a !~ $0{print}; {a=$0}' filename
Remove duplicate entries in a file without sorting
awk '!x[$0]++' filename
Exclude multiple columns
awk '{$1=$3=""}1' filename
Substitute foo for bar on lines matching regexp
awk '/regexp/{gsub(/foo/, "bar")};{print}' filename
Add some characters at the beginning of matching lines
awk '/regexp/{sub(/^/, "++++"); print;next;}{print}' filename
Get the last hour of Apache logs
awk '/'$(date -d "1 hours ago" "+%d\\/%b\\/%Y:%H:%M")'/,/'$(date "+%d\\/%b\\/%Y:%H:%M")'/ { print $0 }' \
/var/log/httpd/access_log
Tool: sed
sed -n 10p /path/to/file
Remove a specific line from a file
sed -i 10d /path/to/file
# alternative (BSD): sed -i'' 10d /path/to/file
Remove a range of lines from a file
sed -i <file> -re '<start>,<end>d'
Replace newline(s) with a space
sed ':a;N;$!ba;s/\n/ /g' /path/to/file

# cross-platform compatible syntax:
sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/ /g' /path/to/file
  • :a create a label a
  • N append the next line to the pattern space
  • $! if not the last line, ba branch (go to) label a
  • s substitute, /\n/ regex for new line, / / by a space, /g global match (as many times as it can)

Alternatives:

# perl version (sed-like speed):
perl -p -e 's/\n/ /' /path/to/file

# bash version (slow):
while read line ; do printf "%s" "$line " ; done < file
Delete string +N next lines
sed '/start/,+4d' /path/to/file
Tool: grep
Search for a “pattern” inside all files in the current directory
grep -rn "pattern"
grep -RnisI "pattern" *
fgrep "pattern" * -R
Show only for multiple patterns
grep 'INFO*'\''WARN' filename
grep 'INFO\|WARN' filename
grep -e INFO -e WARN filename
grep -E '(INFO|WARN)' filename
egrep "INFO|WARN" filename
Except multiple patterns
grep -vE '(error|critical|warning)' filename
Show data from file without comments
grep -v ^[[:space:]]*# filename
Show data from file without comments and new lines
egrep -v '#|^$' filename
Show strings with a dash/hyphen
grep -e -- filename
grep -- -- filename
grep "\-\-" filename
Remove blank lines from a file and save output to new file
grep . filename > newfilename
Tool: perl
Search and replace (in place)
perl -i -pe's/SEARCH/REPLACE/' filename
Edit of *.conf files changing all foo to bar (and backup original)
perl -p -i.orig -e 's/\bfoo\b/bar/g' *.conf
Prints the first 20 lines from *.conf files
perl -pe 'exit if $. > 20' *.conf
Search lines 10 to 20
perl -ne 'print if 10 .. 20' filename
Delete first 10 lines (and backup original)
perl -i.orig -ne 'print unless 1 .. 10' filename
Delete all but lines between foo and bar (and backup original)
perl -i.orig -ne 'print unless /^foo$/ .. /^bar$/' filename
Reduce multiple blank lines to a single line
perl -p -i -00pe0 filename
Convert tabs to spaces (1t = 2sp)
perl -p -i -e 's/\t/  /g' filename
Read input from a file and report number of lines and characters
perl -lne '$i++; $in += length($_); END { print "$i lines, $in characters"; }' filename

Shell functions  [TOC]

Table of Contents
Domain resolve
# Dependencies:
#   - curl
#   - jq

function DomainResolve() {

  local _host="$1"

  local _curl_base="curl --request GET"
  local _timeout="15"

  _host_ip=$($_curl_base -ks -m "$_timeout" "https://dns.google.com/resolve?name=${_host}&type=A" | \
  jq '.Answer[0].data' | tr -d "\"" 2>/dev/null)

  if [[ -z "$_host_ip" ]] || [[ "$_host_ip" == "null" ]] ; then

    echo -en "Unsuccessful domain name resolution.\\n"

  else

    echo -en "$_host > $_host_ip\\n"

  fi

}

Example:

shell> DomainResolve nmap.org
nmap.org > 45.33.49.119

shell> DomainResolve nmap.org
Unsuccessful domain name resolution.
Get ASN
# Dependencies:
#   - curl

function GetASN() {

  local _ip="$1"

  local _curl_base="curl --request GET"
  local _timeout="15"

  _asn=$($_curl_base -ks -m "$_timeout" "http://ip-api.com/line/${_ip}?fields=as")

  _state=$(echo $?)

  if [[ -z "$_ip" ]] || [[ "$_ip" == "null" ]] || [[ "$_state" -ne 0 ]]; then

    echo -en "Unsuccessful ASN gathering.\\n"

  else

    echo -en "$_ip > $_asn\\n"

  fi

}

Example:

shell> GetASN 1.1.1.1
1.1.1.1 > AS13335 Cloudflare, Inc.

shell> GetASN 0.0.0.0
Unsuccessful ASN gathering.
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