VIN VIN Technologies › Labs › Routing and security
Firewall rules
Routing and security · free online experiment, runs in your browser with no install or sign-up.
Open this experiment in the network simulator
Objective
A firewall allows ping and web traffic (port 80) from the LAN to the server but blocks port 23 (telnet).
Procedure
- Run: ping and the port-80 transfer work, the telnet (port 23) transfer never connects.
- Edit the firewall rules (select FW) and swap 'deny … 23' for 'allow … 23': telnet works.
Theory
Rules are checked top to bottom, first match wins; unmatched packets follow the default policy. A TCP connection whose SYN is dropped never opens.
Network blocks used
Firewall, Host / PC, Server (DNS + DHCP)
Open this experiment in the network simulator