25
SMTP
Simple Mail Transfer Protocol
TCP
Email
Port Information
Port Number
25
Protocol
TCP
Category
Common Usage
URL with Port
http://localhost:25 https://example.com:25
Node.js/Express Server
const express = require('express');
const app = express();
const PORT = 25;
app.listen(PORT, () => {
console.log(`Server running on port ${PORT}`);
});Docker Port Mapping
docker run -p 25:25 myapp # In docker-compose.yml ports: - "25:25"
Firewall Configuration
# Linux/Ubuntu firewall sudo ufw allow 25/tcp # Check if port is in use netstat -an | grep 25
Port 25 - SMTP
Simple Mail Transfer Protocol This is a TCP port commonly used in email applications. Port numbers range from 0-65535, with ports 0-1023 being well-known system ports, 1024-49151 being registered ports, and 49152-65535 being dynamic/private ports.