Nmap

Tudo (ou quase tudo) sobre nmap

Nmap (“Network Mapper”) é uma ferramenta open source para exploração de rede e útil para auditar a segurança do ambiente. Foi concebido para rapidamente scanear hosts e serviços em grandes redes ou para um host específico.

Ele é capaz de descobrir portas abertas, serviços rodando, versão de sistema operacional, quais tipos de filtros e firewall estão sendo usados no host, etc.

Especificando o alvo

Opção	Exemplo	Descrição
	nmap 192.168.1.1	Varre um único IP
	nmap 192.168.1.1 192.168.2.1	Varre IPs específicos
	nmap 192.168.1.1-254	Varre um range de IPs
	nmap scanme.nmap.org	Varre um domínio
	nmap 192.168.1.0/24	Varre rede inteira
-iL	nmap -iL targets.txt	Varre alvos de um arquivo
-iR	nmap -iR 100	Varre 100 random hosts
--exclude	nmap --exclude 192.168.1.1	Excluir o host da varredura

Técnicas básicas de Scan

Opção	Exemplo	Descrição
-sS	nmap 192.168.1.1 -sS	TCP SYN port scan (Default)
-sT	nmap 192.168.1.1 -sT	TCP connect port scan (Default without root privilege)
-sU	nmap 192.168.1.1 -sU	UDP port scan
-sA	nmap 192.168.1.1 -sA	TCP ACK port scan
-sW	nmap 192.168.1.1 -sW	TCP Window port scan
-sM	nmap 192.168.1.1 -sM	TCP Maimon port scan

Descoberta de hosts na rede

Opção	Exemplo	Descrição
-sL	nmap 192.168.1.1-3 -sL	Não varre nada. Apenas listas alvos
-sn	nmap 192.168.1.1/24 -sn	Sem varredura. Apenas descobre hosts
-Pn	nmap 192.168.1.1-5 -Pn	Sem descoberta de hosts. Apenas varre portas
-PS	nmap 192.168.1.1-5 -PS22-25,80	TCP SYN discovery on port x. Port 80 by default
-PA	nmap 192.168.1.1-5 -PA22-25,80	TCP ACK discovery on port x. Port 80 by default
-PU	nmap 192.168.1.1-5 -PU53	UDP discovery on port x. Port 40125 by default
-PR	nmap 192.168.1.1-1/24 -PR	ARP discovery on local network
-n	nmap 192.168.1.1 -n	Nunca executa descoberta de DNS

Enumerar portas específicas

Opção	Exemplo	Descrição
-p	nmap 192.168.1.1 -p 21	Port scan na porta 21
-p	nmap 192.168.1.1 -p 21-100	Varre portas 21 até 100
-p	nmap 192.168.1.1 -p U:53,T:21-25,80	Varre portas UDP e TCP específicas
-p-	nmap 192.168.1.1 -p-	Varre todas as portas possíveis
-p	nmap 192.168.1.1 -p http,https	Varre portas de um serviço específico
-F	nmap 192.168.1.1 -F	Varredura rápida de portas (100 portas)
--top-ports	nmap 192.168.1.1 --top-ports 2000	Varre as 2 mil portas principais

Detecção de Serviço e Versão

Opção	Exemplo	Descrição
-sV	nmap 192.168.1.1 -sV	Tenta descobrir versão dos serviços
-sV --version-intensity	nmap 192.168.1.1 -sV --version-intensity 8	Nível de intensidade de 0 a 9. Número alto aumenta chance de assertividade
-sV --version-light	nmap 192.168.1.1 -sV --version-light	Habilita light mode. Menos assertivo. Mais rápido
-sV --version-all	nmap 192.168.1.1 -sV --version-all	Habilita nível de intensidade 9. Mais assertivo. Mais lento.
-A	nmap 192.168.1.1 -A	Habilita todas as opções de descoberta de versões e SO

Detecção de Sistema Operacional

Opção	Exemplo	Descrição
-O	nmap 192.168.1.1 -O	Remote OS detection using TCP/IP stack fingerprinting
-O --osscan-limit	nmap 192.168.1.1 -O --osscan-limit	If at least one open and one closed TCP port are not found it will not try OS detection against host
-O --osscan-guess	nmap 192.168.1.1 -O --osscan-guess	Makes Nmap guess more aggressively
-O --max-os-tries	nmap 192.168.1.1 -O --max-os-tries 1	Set the maximum number x of OS detection tries against a target
-A	nmap 192.168.1.1 -A	Enables OS detection, version detection, script scanning, and traceroute

Tempo, performance e ocultação

Opção	Exemplo	Descrição
-T0	nmap 192.168.1.1 -T0	Paranoid (0) Intrusion Detection System evasion
-T1	nmap 192.168.1.1 -T1	Sneaky (1) Intrusion Detection System evasion
-T2	nmap 192.168.1.1 -T2	Polite (2) slows down the scan to use less bandwidth and use less target machine resources
-T3	nmap 192.168.1.1 -T3	Normal (3) which is default speed
-T4	nmap 192.168.1.1 -T4	Aggressive (4) speeds scans; assumes you are on a reasonably fast and reliable network
-T5	nmap 192.168.1.1 -T5	Insane (5) speeds scan; assumes you are on an extraordinarily fast network

Opção	Exemplo	Descrição
--host-timeout <time>	1s; 4m; 2h	Give up on target after this long
--min-rtt-timeout/max-rtt-timeout/initial-rtt-timeout <time>	1s; 4m; 2h	Specifies probe round trip time
--min-hostgroup/max-hostgroup <size<size>	50; 1024	Parallel host scan group sizes
--min-parallelism/max-parallelism <numprobes>	10; 1	Probe parallelization
--scan-delay/--max-scan-delay <time>	20ms; 2s; 4m; 5h	Adjust delay between probes
--max-retries <tries>	3	Specify the maximum number of port scan probe retransmissions
--min-rate <number>	100	Send packets no slower than <numberr> per second
--max-rate <number>	100	Send packets no faster than <number> per second

Trabalhando com Scripts NSE

Opção	Exemplo	Descrição
-sC	nmap 192.168.1.1 -sC	Scan with default NSE scripts. Considered useful for discovery and safe
--script default	nmap 192.168.1.1 --script default	Scan with default NSE scripts. Considered useful for discovery and safe
--script	nmap 192.168.1.1 --script=banner	Scan with a single script. Example banner
--script	nmap 192.168.1.1 --script=http*	Scan with a wildcard. Example http
--script	nmap 192.168.1.1 --script=http,banner	Scan with two scripts. Example http and banner
--script	nmap 192.168.1.1 --script "not intrusive"	Scan default, but remove intrusive scripts
--script-args	nmap --script snmp-sysdescr --script-args snmpcommunity=admin 192.168.1.1	NSE script with arguments

Exemplo úteis de scripts

Comando	Descrição
nmap -Pn --script=http-sitemap-generator scanme.nmap.org	http site map generator
nmap -n -Pn -p 80 --open -sV -vvv --script banner,http-title -iR 1000	Fast search for random web servers
nmap -Pn --script=dns-brute domain.com	Brute forces DNS hostnames guessing subdomains
nmap -n -Pn -vv -O -sV --script smb-enum*,smb-ls,smb-mbenum,smb-os-discovery,smb-s*,smb-vuln*,smbv2* -vv 192.168.1.1	Safe SMB scripts to run
nmap --script whois* domain.com	Whois query
nmap -p80 --script http-unsafe-output-escaping scanme.nmap.org	Detect cross site scripting vulnerabilities
nmap -p80 --script http-sql-injection scanme.nmap.org	Check for SQL injections

Firewall / IDS Evasion and Spoofing

Opção	Exemplo	Descrição
-f	nmap 192.168.1.1 -f	Requested scan (including ping scans) use tiny fragmented IP packets. Harder for packet filters
--mtu	nmap 192.168.1.1 --mtu 32	Set your own offset size
-D	nmap -D 192.168.1.101,192.168.1.102, 192.168.1.103,192.168.1.23 192.168.1.1	Send scans from spoofed IPs
-D	nmap -D decoy-ip1,decoy-ip2,your-own-ip,decoy-ip3,decoy-ip4 remote-host-ip	Above example explained
-S	nmap -S www.microsoft.com www.facebook.com	Scan Facebook from Microsoft (-e eth0 -Pn may be required)
-g	nmap -g 53 192.168.1.1	Use given source port number
--proxies	nmap --proxies http://192.168.1.1:8080, http://192.168.1.2:8080 192.168.1.1	Relay connections through HTTP/SOCKS4 proxies
--data-length	nmap --data-length 200 192.168.1.1	Appends random data to sent packets

Exemplo de IDS Evasion:

nmap -f -t 0 -n -Pn –data-length 200 -D 192.168.1.101,192.168.1.102,192.168.1.103,192.168.1.23 192.168.1.1

Saída do comando

Opção	Exemplo	Descrição
-oN	nmap 192.168.1.1 -oN normal.file	Normal output to the file normal.file
-oX	nmap 192.168.1.1 -oX xml.file	XML output to the file xml.file
-oG	nmap 192.168.1.1 -oG grep.file	Grepable output to the file grep.file
-oA	nmap 192.168.1.1 -oA results	Output in the three major formats at once
-oG -	nmap 192.168.1.1 -oG -	Grepable output to screen. -oN -, -oX - also usable
--append-output	nmap 192.168.1.1 -oN file.file --append-output	Append a scan to a previous scan file
-v	nmap 192.168.1.1 -v	Increase the verbosity level (use -vv or more for greater effect)
-d	nmap 192.168.1.1 -d	Increase debugging level (use -dd or more for greater effect)
--reason	nmap 192.168.1.1 --reason	Display the reason a port is in a particular state, same output as -vv
--open	nmap 192.168.1.1 --open	Only show open (or possibly open) ports
--packet-trace	nmap 192.168.1.1 -T4 --packet-trace	Show all packets sent and received
--iflist	nmap --iflist	Shows the host interfaces and routes
--resume	nmap --resume results.file	Resume a scan

Exemplos úteis de saída dos comandos:

Comando	Descrição
nmap -p80 -sV -oG - --open 192.168.1.1/24 | grep open	Scan for web servers and grep to show which IPs are running web servers
nmap -iR 10 -n -oX out.xml | grep "Nmap" | cut -d " " -f5 > live-hosts.txt	Generate a list of the IPs of live hosts
nmap -iR 10 -n -oX out2.xml | grep "Nmap" | cut -d " " -f5 >> live-hosts.txt	Append IP to the list of live hosts
ndiff scanl.xml scan2.xml	Compare output from nmap using the ndif
xsltproc nmap.xml -o nmap.html	Convert nmap xml files to html files
grep " open " results.nmap | sed -r 's/ +/ /g' | sort | uniq -c | sort -rn | less	Reverse sorted list of how often ports turn up

Opções diversas

Opção	Exemplo	Descrição
-6	nmap -6 2607:f0d0:1002:51::4	Habilita IPv6 scan
-h	nmap -h	Tela de ajuda do nmap

Outros comandos úteis

Comando	Descrição
nmap -iR 10 -PS22-25,80,113,1050,35000 -v -sn	Discovery only on ports x, no port scan
nmap 192.168.1.1-1/24 -PR -sn -vv	Arp discovery only on local network, no port scan
nmap -iR 10 -sn -traceroute	Traceroute to random targets, no port scan
nmap 192.168.1.1-50 -sL --dns-server 192.168.1.1	Query the Internal DNS for hosts, list targets only