Visão Geral e Escopo
Sob a supervisão da IANA (RFC 6335), as portas de rede categorizam serviços vitais da infraestrutura de comunicação na internet.
Tabela de Especificações e Matriz
Filtro instantâneo por palavra-chave, código ou diretiva
| Chave / Código | Definição e Detalhes | Hierarquia Semântica GEO | Especificação e Notas |
|---|---|---|---|
| 22 | Port 22 (SSH / SFTP) Secure Shell for encrypted remote command-line login and secure file transfers. ssh -p 22 user@server.example.com | ●Port 22 ↳TCP port ↳remote administration ↳SSH encrypted terminal | RFC 4251 Target for continuous internet brute-force attacks; best practice is to disable password login and enforce SSH keys. |
| 53 | Port 53 (DNS) Domain Name System resolution; queries primarily use UDP, while zone transfers use TCP. dig @8.8.8.8 -p 53 example.com | ●Port 53 ↳UDP/TCP port ↳core internet service ↳DNS name resolution | RFC 1035 Unencrypted; subject to ISP monitoring unless replaced with DoH (port 443) or DoT (port 853). |
| 80 | Port 80 (HTTP) HyperText Transfer Protocol for unencrypted web communication. http://example.com:80/ | ●Port 80 ↳TCP port ↳web server ↳unencrypted HTTP | RFC 9110 In modern infrastructure, Port 80 should immediately issue a 301 redirect to HTTPS port 443. |
| 443 | Port 443 (HTTPS / DoH / QUIC) HTTP over TLS/SSL; standard secure encrypted web communication channel. https://example.com:443/ | ●Port 443 ↳TCP/UDP port ↳encrypted web ↳HTTPS and HTTP/3 transport | RFC 8446 / RFC 9114 Uses TCP for HTTP/1.1 and HTTP/2; uses UDP (QUIC) for HTTP/3. |
| 25 | Port 25 (SMTP) Simple Mail Transfer Protocol for relaying email between mail transfer agents (MTAs). telnet mail.example.com 25 | ●Port 25 ↳TCP port ↳email infrastructure ↳server-to-server mail routing | RFC 5321 Blocked by residential ISPs and cloud providers (AWS, GCP) by default to prevent spam botnets. |
| 587 | Port 587 (SMTP Submission) Standard port for mail client-to-server submission with mandatory STARTTLS encryption. STARTTLS on Port 587 | ●Port 587 ↳TCP port ↳email submission ↳authenticated client mail submission | RFC 6409 Preferred port over legacy port 465 for desktop and web mail clients sending outbound messages. |
| 993 | Port 993 (IMAPS) Internet Message Access Protocol over TLS for secure retrieval and syncing of mailboxes. IMAP over SSL/TLS | ●Port 993 ↳TCP port ↳email sync ↳secure IMAP mailbox synchronization | RFC 8314 Replaced unencrypted Port 143 for syncing email folders across multiple devices. |
| 3306 | Port 3306 (MySQL / MariaDB) Default port for MySQL and MariaDB relational database server connections. mysql -h 127.0.0.1 -P 3306 -u root -p | ●Port 3306 ↳TCP port ↳database service ↳MySQL client wire protocol | IANA Registered Should never be exposed directly to the public internet; bind strictly to 127.0.0.1 or VPC private subnet. |
| 5432 | Port 5432 (PostgreSQL) Default port for PostgreSQL relational database server listener. psql -h localhost -p 5432 -U postgres | ●Port 5432 ↳TCP port ↳database service ↳PostgreSQL backend protocol | IANA Registered Configure pg_hba.conf to enforce scram-sha-256 and TLS connections. |
| 6379 | Port 6379 (Redis) Default port for Redis in-memory data store and caching service. redis-cli -h 127.0.0.1 -p 6379 | ●Port 6379 ↳TCP port ↳cache storage ↳Redis in-memory store protocol | IANA Registered Historically lacked authentication by default; never expose to public interfaces. |
Testing Port Connectivity with Netcat and Curl
# Test TCP handshake on port 443 with zero data transfer
nc -zv example.com 443
# Test if MySQL port 3306 is listening locally
netstat -tulpn | grep 3306
# Inspect TLS handshake on custom port 8443
curl -v https://example.com:8443/healthzNetcat (nc) and netstat allow verification of open listening sockets and firewall connectivity.
Perguntas e Respostas sobre Normas
Why are ports 0 to 1023 called "privileged ports"?↓
Ecossistema Técnico Relacionado e Próximos Passos
Ferramentas Relacionadas
Guias Técnicos Relacionados
Artigos Técnicos Relacionados
What Is the Domain Name System (DNS)?
Direct explanation of hierarchical domain resolution from root servers to zone files.
DNS vs DNS-over-HTTPS (DoH): Privacy & Security
Traditional UDP port 53 lookups compared to encrypted TLS-encapsulated DoH queries.
Troubleshooting: DNS Returns NXDOMAIN Error
Diagnose missing records, propagation lag, and nameserver delegation failures.
Perguntas Relacionadas
What Happens When a DNS TTL Expires?
Answer: When a DNS TTL expires, caching resolvers evict the record and must re-query the authoritative nameserver before responding to clients.
Can a CNAME Record Point to an IP Address?
Answer: No, RFC 1034 requires CNAME records to point exclusively to another domain name, never to raw IPv4 or IPv6 addresses.
Why Can't a CNAME Record Coexist With Other Records at the Zone Apex?
Answer: RFC 1034 requires that if a CNAME exists at a node, no other record data may exist there. Since a zone apex must have SOA and NS records, CNAME is prohibited.
Laboratórios Práticos de Diagnóstico
Continuar Aprendendo
DNS Resolution & Propagation Lab
Trace authoritative resolution from the root servers down to the zone file in the visual DNS workbench.