Networking
Risk: High
Port 3128 — Squid HTTP Proxy / Caching
Port 3128 is the default listening port for Squid Web Proxy Cache, utilized in enterprise networks for content filtering, web acceleration, and internet access control.
PORT NUMBER
3128
PROTOCOL
TCP
DEFAULT PROCESS
squid
FIREWALL TARGET
3128/tcp
Instant Terminal Fixes for Port 3128
macOS & Linux Terminal
1. Check who is listening on port 3128:
sudo lsof -i :3128 || sudo ss -tulpn | grep ":3128 "2. Kill process occupying port 3128 (EADDRINUSE fix):
sudo systemctl stop squid || sudo killall squid3. UFW Firewall Allow rule:
sudo ufw allow 3128/tcpWindows PowerShell (Admin)
1. Check listening port:
Get-NetTCPConnection -LocalPort 31282. Force kill process on port 3128:
Stop-Service Squid -Force -ErrorAction SilentlyContinue3. Docker Port Forwarding Mapping:
docker run -d -p 3128:3128 ubuntu/squidCommon Error Encountered
Squid Proxy Error: Access Denied / Connection to localhost:3128 failed.
Security Advisory & Hardening
Open Squid proxies allow external threat actors to tunnel traffic through your IP, masking malicious actions and consuming bandwidth. Enforce strict ACLs in squid.conf.
Frequently Asked Questions
Port 3128 Questions & Answers
Common questions regarding default services, kill commands, and firewall configurations.
Port 3128 is commonly used for Squid HTTP Proxy / Caching. Port 3128 is the default listening port for Squid Web Proxy Cache, utilized in enterprise networks for content filtering, web acceleration, and internet access control.