Inbound Traffic Blocked, Check Firewall Settings May 2026

Chain INPUT (policy DROP)

Temporarily disable the firewall to confirm the issue (do not do this in production).

# Linux / macOS sudo netstat -tulpn | grep LISTEN # or ss -tuln netstat -an | findstr "LISTENING" inbound traffic blocked, check firewall settings

Issue: Users or services cannot connect to your server, application, or device from an external network (e.g., the internet or another subnet). Connection attempts time out or are actively rejected.

sudo ufw status verbose If inactive, enable it with sudo ufw enable . If active, check for rules like Deny from any or missing Allow rules for your port. Chain INPUT (policy DROP) Temporarily disable the firewall

sudo pfctl -s rules Disable temporarily:

# Test TCP port nc -zv <target-ip> <port> telnet <target-ip> <port> Test with curl (HTTP) curl -v http://<target-ip>:<port> sudo ufw status verbose If inactive, enable it

sudo iptables -L -n -v Look for a default policy of DROP or REJECT on the INPUT chain. Example blocking line: