iptables Confusion

Applications IP Networking
1

Hi all,

I am looking to get a few questions answered but I am having trouble finding an answer to these specific questions online.

  1. Order of operations: THere are plenty of fancy diagrams online that illustrate the order of operations for IPTables (Raw before Mangle for example) but what I cannot find an answer to is if for example, The MANGLE PREROUTING chain had a rule to ACCEPT packets destined to 4.2.2.2, would the packet still be subject to the remaining tables? IE, would that packet then be examined by the NAT table, then the filter table, and their set of chains and rules? Or once an accept/permit is determined, is the packet good to go and no longer subject to further processing?

  2. I am used to Vendor-based Firewall solutions such as Cisco, FortiGate, Palo Alto and such. All of these Firewalls have an IMPLICIT deny, but as far as I can tell, IPTables does not - is this correct? It looks as though an Implicit ACCEPT is the norm.

Thank you for your time!

Kyle

2

I would use ufw - Uncomplicated Firewall on ubuntu. its very easy to use.

As far as i understand it is still a IMPLICIT deny