jump - jump to the user defined chain specified by the value of jump-target parameter.fasttrack-connection - process packets from a connection using FastPath by enabling FastTrack for the connection.add-src-to-address-list - add source address to address list specified by address-list parameter.add-dst-to-address-list - add destination address to address list specified by address-list parameter.Packet is not passed to next firewall rule. If a packet has not matched any rule within the built-in chain, then it is accepted.Īction to take if packet is matched by the rule: If a packet matches the criteria of the rule, then the specified action is performed on it, and no more rules are processed in that chain (the exception is the passthrough action). When processing a chain, rules are taken from the chain in the order they are listed there from top to bottom. Packet flow diagrams illustrate how packets are processed in RouterOS. Packets passing through the router are not processed against the rules of the output chain output - used to process packets originated from the router and leaving it through one of the interfaces.forward - used to process packets passing through the router.Packets passing through the router are not processed against the rules of the input chain input - used to process packets entering the router through one of the interfaces with the destination IP address which is one of the router's addresses.There are three predefined chains, which cannot be deleted:
Then rules that perform matching against separate ports can be added to mychain chain without specifying the IP addresses. Of course, it could be achieved by adding as many rules with IP address:port match as required to the forward chain, but a better way could be to add one rule that matches traffic from a particular IP address, e.g.: /ip firewall filter add src-address=1.1.1.2/32 jump-target="mychain" and in case of successfull match passes control over the IP packet to some other chain, id est mychain in this example. For example a packet should be matched against the IP address:port pair. It allows a packet to be matched against one common criterion in one chain, and then passed over for processing against some other common criteria to another chain.
Each rule consists of two parts - the matcher which matches traffic flow against given conditions and the action which defines what to do with the matched packet.įirewall filtering rules are grouped together in chains. The firewall operates by means of firewall rules.
protocol options (ICMP type and code fields, TCP flags, IP options and MSS).IP addresses (network or list) and address types (broadcast, local, multicast, unicast).
MikroTik RouterOS has very powerful firewall implementation with features including: Properly configured firewall plays a key role in efficient and secure network infrastrure deployment.
Firewalls are used as a means of preventing or minimizing the security risks inherent in connecting to other networks. Such break-ins may result in private data being stolen and distributed, valuable data being altered or destroyed, or entire hard drives being erased. Whenever different networks are joined together, there is always a threat that someone from outside of your network will break into your LAN. Network firewalls keep outside threats away from sensitive data available inside the network. Along with the Network Address Translation it serves as a tool for preventing unauthorized access to directly attached networks and the router itself as well as a filter for outgoing traffic. The firewall implements packet filtering and thereby provides security functions that are used to manage data flow to, from and through the router.