iptables Linux . Firewall, . !
, . . , , - .
Firewall Chains
() . , (), : , , , . Mikrotik : Input, Output Forward.
Input Chain
Input . IP - . , WAN, , . , (, Winbox SSH VLAN ).
VLAN , .
Output Chain
, . , : , DNS ICMP .
Forward Chain
Mikrotik . : , LAN . , WAN.
Firewall Actions
, : accept (), drop () (reject).
Accept
. .
Reject
( reject) , . , .
: , REJECT . , , DROP.
Drop
. Mikrotik .
Firewall Rules
Firewall , , . IP (/ ), (chains), (actions), . , . , DENY ALL ( ).
Chains
(chain). , ( ).
! , .
Actions
: (accept), (reject) (drop). .
, : , IP ( /32 , /24, ). , (eth/GRE).
. , .

Firewall:
- - , . , .
- - , IP VPN . .
- deny all - , , , ( L7, ) . , : , - .
- ! - , , . , :) . , Nmap.