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ProWebTools v2.0
Free Online Developer Utilities
DevOps & System Admin

Common Network Ports & Firewall Rules

Standard TCP/UDP port references, vulnerability warnings, and instant UFW/iptables commands for Linux server administrators.

21 TCP
Legacy / Insecure

FTP (File Transfer Protocol)

File Transfer

Used for transferring computer files between a client and server. Credentials are sent in cleartext.

Security Note: Deprecated in favor of SFTP (SSH Port 22) or FTPS (FTP over TLS). Should never be exposed publicly.
Allow in UFW: 
sudo ufw allow 21/tcp
22 TCP
Standard

SSH (Secure Shell) / SFTP

Remote Administration

Encrypted network protocol for operating network services securely over an unsecured network.

Security Note: Frequently targeted by automated brute-force attacks. Recommended: disable root login and use public key authentication.
Allow in UFW: 
sudo ufw allow 22/tcp
25 TCP
Standard

SMTP (Simple Mail Transfer Protocol)

Email Routing

Default port for mail routing between email servers (MTA to MTA).

Security Note: Many cloud providers (AWS, DigitalOcean, Hetzner) block outbound port 25 to prevent spam.
Allow in UFW: 
sudo ufw allow 25/tcp
53 TCP/UDP
Core

DNS (Domain Name System)

Network Infrastructure

Translates human-readable domain names (e.g. prowebtools.online) into IP addresses.

Security Note: Vulnerable to DNS Amplification DDoS attacks if running an open recursive resolver.
Allow in UFW: 
sudo ufw allow 53
80 TCP
Standard

HTTP (Hypertext Transfer Protocol)

Web Services

Standard unencrypted web traffic port. Now primarily used to redirect visitors to HTTPS (443).

Security Note: Always redirect HTTP to HTTPS (Port 443) to prevent eavesdropping and session hijacking.
Allow in UFW: 
sudo ufw allow 80/tcp
110 TCP
Legacy

POP3 (Post Office Protocol v3)

Email Retrieval

Used by local email clients to retrieve emails from a remote server over an unencrypted connection.

Security Note: Use POP3S (Port 995) or IMAPS (Port 993) instead.
Allow in UFW: 
sudo ufw allow 110/tcp
123 UDP
Core

NTP (Network Time Protocol)

Time Sync

Synchronizes computer clock times over packet-switched, variable-latency data networks.

Security Note: Ensure NTP monlist is disabled to avoid NTP amplification attack exploitation.
Allow in UFW: 
sudo ufw allow 123/udp
143 TCP
Standard

IMAP (Internet Message Access Protocol)

Email Retrieval

Retrieves email messages without downloading the entire inbox to the local device.

Security Note: Always use IMAPS (Port 993) with TLS encryption.
Allow in UFW: 
sudo ufw allow 143/tcp
443 TCP/UDP
Essential

HTTPS (HTTP Secure) / HTTP/3 QUIC

Web Services

Secure, TLS/SSL-encrypted web traffic. HTTP/3 also uses UDP port 443 via QUIC protocol.

Security Note: Enforce modern TLS 1.3/1.2 protocols and disable weak ciphers (SSLv3, TLS 1.0, 1.1).
Allow in UFW: 
sudo ufw allow 443/tcp && sudo ufw allow 443/udp
465 TCP
Standard

SMTPS (SMTP over SSL/TLS)

Email Submission

Secure submission of email messages by end-user email clients (MUAs) to mail servers.

Security Note: Recommended default for email client outbound sending with SSL wrapper.
Allow in UFW: 
sudo ufw allow 465/tcp
587 TCP
Standard

SMTP Submission (STARTTLS)

Email Submission

Email message submission port specified by RFC 6409, utilizing STARTTLS upgrade.

Security Note: Standard port for WordPress, web forms, and SaaS apps sending transactional email.
Allow in UFW: 
sudo ufw allow 587/tcp
993 TCP
Standard

IMAPS (IMAP over SSL/TLS)

Email Retrieval

Encrypted IMAP protocol for securely retrieving and synchronizing email folders across devices.

Security Note: Industry standard for secure mobile and desktop mail apps.
Allow in UFW: 
sudo ufw allow 993/tcp
995 TCP
Standard

POP3S (POP3 over SSL/TLS)

Email Retrieval

Encrypted POP3 protocol for downloading inbox emails securely.

Security Note: Secure alternative to plaintext port 110.
Allow in UFW: 
sudo ufw allow 995/tcp
1433 TCP
Internal Only

Microsoft SQL Server (MS SQL)

Databases

Default listener port for Microsoft SQL Server database engine.

Security Note: CRITICAL: Never expose to 0.0.0.0/0. Bind to 127.0.0.1 or access only over VPN/private VPC.
Allow in UFW: 
sudo ufw allow from 10.0.0.0/8 to any port 1433 proto tcp
3306 TCP
Internal Only

MySQL / MariaDB

Databases

Standard connection port for MySQL and MariaDB relational database management systems.

Security Note: CRITICAL: Bind to localhost (bind-address = 127.0.0.1). Automated ransomware bots scan this port 24/7.
Allow in UFW: 
sudo ufw allow from 10.0.0.5 to any port 3306 proto tcp
3389 TCP/UDP
High Risk

RDP (Remote Desktop Protocol)

Remote Administration

Proprietary Microsoft protocol providing graphical interface to connect to Windows servers.

Security Note: High risk when internet-facing. Always place behind VPN or Cloudflare Zero Trust Access.
Allow in UFW: 
sudo ufw allow from 192.168.1.0/24 to any port 3389 proto tcp
5432 TCP
Internal Only

PostgreSQL Database

Databases

Default port for PostgreSQL open-source object-relational database system.

Security Note: Configure `pg_hba.conf` carefully and never allow open trust connections on public IPs.
Allow in UFW: 
sudo ufw allow from 10.0.0.0/16 to any port 5432 proto tcp
6379 TCP
Internal Only

Redis In-Memory Cache

Databases & Caching

In-memory key-value data structure store used as a database, cache, and message broker.

Security Note: EXTREME RISK: Redis defaults have no password. If exposed to the internet, servers can be compromised in seconds.
Allow in UFW: 
sudo ufw allow from 127.0.0.1 to any port 6379 proto tcp
8080 TCP
Common Dev Port

HTTP Alternate / Tomcat / Proxy

Web Services & Dev

Common alternative port for web servers (Apache Tomcat, Spring Boot, Jenkins, Node.js staging).

Security Note: Ensure admin consoles (Jenkins, Tomcat Manager) require strong authentication.
Allow in UFW: 
sudo ufw allow 8080/tcp
27017 TCP
Internal Only

MongoDB NoSQL Database

Databases

Default connection port for MongoDB document database instances.

Security Note: Always enable authentication (auth = true) and bind to internal interfaces only.
Allow in UFW: 
sudo ufw allow from 10.0.0.0/8 to any port 27017 proto tcp