Network Discovery



  • Ping sweep (No port scan, No DNS resolution)
nmap -sn -n --disable-arp-ping | grep -v "host down"
-sn : Disable port scanning. Host discovery only.
-n : Never do DNS resolution
  • Basic NMAP
sudo nmap -sSV -p- -oA OUTPUTFILE -T4
sudo nmap -sSV -oA OUTPUTFILE -T4 -iL INPUTFILE.csv

• the flag -sSV defines the type of packet to send to the server and tells Nmap to try and determine any service on open ports
• the -p- tells Nmap to check all 65,535 ports (by default it will only check the most popular 1,000)
• is the IP address to scan
• -oA OUTPUTFILE tells Nmap to output the findings in its three major formats at once using the filename "OUTPUTFILE"
• -iL INPUTFILE tells Nmap to use the provided file as inputs

This configuration is enough to do a basic check for a CTF VM

nmap -sV -sC -oA ~/nmap-initial

-sV : Probe open ports to determine service/version info
-sC : to enable the script
-oA : to save the results

After this quick command you can add "-p-" to run a full scan while you work with the previous result
  • Aggressive NMAP
nmap -A -T4
• -A: Enable OS detection, version detection, script scanning, and traceroute
• -T4: Defines the timing for the task (options are 0-5 and higher is faster)
  • Using searchsploit to detect vulnerable services
nmap -p- -sV -oX a.xml IP_ADDRESS; searchsploit --nmap a.xml
  • Generating nice scan report
nmap -sV IP_ADDRESS -oX scan.xml && xsltproc scan.xml -o "`date +%m%d%y`_report.html"
  • NMAP Scripts
nmap -sC : equivalent to --script=default

nmap --script 'http-enum' -v -p80 -oN http-enum.nmap
80/tcp open  http
| http-enum:
|   /phpmyadmin/: phpMyAdmin
|   /.git/HEAD: Git folder
|   /css/: Potentially interesting directory w/ listing on 'apache/2.4.10 (debian)'
|_  /image/: Potentially interesting directory w/ listing on 'apache/2.4.10 (debian)'

nmap --script smb-enum-users.nse -p 445 [target host]
Host script results:
| smb-enum-users:
|   METASPLOITABLEbackup (RID: 1068)
|     Full name:   backup
|     Flags:       Account disabled, Normal user account
|     Full name:   bin
|     Flags:       Account disabled, Normal user account
|   METASPLOITABLEmsfadmin (RID: 3000)
|     Full name:   msfadmin,,,
|     Flags:       Normal user account

List Nmap scripts : ls /usr/share/nmap/scripts/

Network Scan with nc and ping

Sometimes we want to perform network scan without any tools like nmap. So we can use the commands ping and nc to check if a host is up and which port is open.
To check if hosts are up on a /24 range

for i in `seq 1 255`; do ping -c 1 -w 1 192.168.1.$i > /dev/null 2>&1; if [ $? -eq 0 ]; then echo "192.168.1.$i is UP"; fi ; done

To check which ports are open on a specific host

for i in {21,22,80,139,443,445,3306,3389,8080,8443}; do nc -z -w 1 $i > /dev/null 2>&1; if [ $? -eq 0 ]; then echo " has port $i open"; fi ; done

Both at the same time on a /24 range

for i in `seq 1 255`; do ping -c 1 -w 1 192.168.1.$i > /dev/null 2>&1; if [ $? -eq 0 ]; then echo "192.168.1.$i is UP:"; for j in {21,22,80,139,443,445,3306,3389,8080,8443}; do nc -z -w 1 192.168.1.$i $j > /dev/null 2>&1; if [ $? -eq 0 ]; then echo "t192.168.1.$i has port $j open"; fi ; done ; fi ; done

Not in one-liner version:

for i in `seq 1 255`; 
    ping -c 1 -w 1 192.168.1.$i > /dev/null 2>&1; 
    if [ $? -eq 0 ]; 
        echo "192.168.1.$i is UP:"; 
        for j in {21,22,80,139,443,445,3306,3389,8080,8443}; 
            nc -z -w 1 192.168.1.$i $j > /dev/null 2>&1; 
            if [ $? -eq 0 ]; 
                echo "t192.168.1.$i has port $j open"; 
            fi ; 
        done ; 
    fi ; 


Searching for subdomains

spyse -target --subdomains

Reverse IP Lookup

spyse -target --domains-on-ip

Searching for SSL certificates

spyse -target --ssl-certificates
spyse -target "org: Microsoft" --ssl-certificates

Getting all DNS records

spyse -target --dns-all


masscan -iL ips-online.txt --rate 10000 -p1-65535 --only-open -oL masscan.out
masscan -e tun0 -p1-65535,U:1-65535 --rate 1000

# find machines on the network
sudo masscan --rate 500 --interface tap0 --router-ip $ROUTER_IP --top-ports 100 $NETWORK -oL masscan_machines.tmp
cat masscan_machines.tmp | grep open | cut -d " " -f4 | sort -u > masscan_machines.lst

# find open ports for one machine
sudo masscan --rate 1000 --interface tap0 --router-ip $ROUTER_IP -p1-65535,U:1-65535 $MACHINE_IP --banners -oL $MACHINE_IP/scans/masscan-ports.lst

# TCP grab banners and services information
TCP_PORTS=$(cat $MACHINE_IP/scans/masscan-ports.lst| grep open | grep tcp | cut -d " " -f3 | tr 'n' ',' | head -c -1)
[ "$TCP_PORTS" ] && sudo nmap -sT -sC -sV -v -Pn -n -T4 -p$TCP_PORTS --reason --version-intensity=5 -oA $MACHINE_IP/scans/nmap_tcp $MACHINE_IP

# UDP grab banners and services information
UDP_PORTS=$(cat $MACHINE_IP/scans/masscan-ports.lst| grep open | grep udp | cut -d " " -f3 | tr 'n' ',' | head -c -1)
[ "$UDP_PORTS" ] && sudo nmap -sU -sC -sV -v -Pn -n -T4 -p$UDP_PORTS --reason --version-intensity=5 -oA $MACHINE_IP/scans/nmap_udp $MACHINE_IP



  • nbtscan
  • nmap
python2.7 ./ -t -o ./results/ --pingsweep --hostnames --services --quick

If you have a segfault with nbtscan, read the following quote.

Permission is denied on the broadcast address (.0) and it segfaults on the gateway (.1) – all other addresses seem fine here.So to mitigate the problem: nbtscan


netdiscover -i eth0 -r
Currently scanning: Finished!   |   Screen View: Unique Hosts

20 Captured ARP Req/Rep packets, from 4 hosts.   Total size: 876
IP            At MAC Address     Count     Len  MAC Vendor / Hostname
192.168.1.AA    68:AA:AA:AA:AA:AA     15     630  Sagemcom
192.168.1.XX    52:XX:XX:XX:XX:XX      1      60  Unknown vendor
192.168.1.YY    24:YY:YY:YY:YY:YY      1      60  QNAP Systems, Inc.
192.168.1.ZZ    b8:ZZ:ZZ:ZZ:ZZ:ZZ      3     126  HUAWEI TECHNOLOGIES CO.,LTD  


responder -I eth0 -A # see NBT-NS, BROWSER, LLMNR requests without responding. -I eth0 -wrf

Alternatively you can use the Windows version


bettercap -X --proxy --proxy-https -T <target IP>
# better cap in spoofing, discovery, sniffer
# intercepting http and https requests,
# targetting specific IP only


This code snippet allows you to sniff/modify SSL traffic if there is a MITM vulnerability using only openssl.
If you can modify /etc/hosts of the client:

sudo echo "[OPENSSL SERVER ADDRESS] []" >> /etc/hosts  # On client host

On our MITM server, if the client accepts self signed certificates (you can use a legit certificate if you have the private key of the legit server):

openssl req -subj '/CN=[]' -batch -new -x509 -days 365 -nodes -out server.pem -keyout server.pem

On our MITM server, we setup our infra:

mkfifo response
sudo openssl s_server -cert server.pem -accept [INTERFACE TO LISTEN TO]:[PORT] -quiet < response | tee | openssl s_client -quiet -servername [] -connect[IP of server to MITM]:[PORT] | tee | cat > response

In this example, traffic is only displayed with tee but we could modify it using sed for example.


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