IPTABLES Guidance - Seeking confirmation of tidbits before rebuilding my firewall

[ericmarceau]

(EDIT: Highlight where conntrack module is “inserted”. Added note that NAT is unwarranted for outgoing packets destined for “localhost”. )

As mentioned before, I will be re-working or re-building my Desktop personal IPTABLES firewall.

I felt it to be a necessary first step to make sure the foundational facts, as I understand them, to be correct.

To that end, I have compiled the attached spreadsheet, as a vehicle to present some of IPTABLES fundamental concepts.

This fourth version ( v 0.4 ) fifth version ( v 0.5 ) is offered, with the request for simple confirmation on sheets 1 and 2, and a request for feedback and references to sources for any corrections applicable. I’ve tried the best I can to make sure I got this 3rd sheet correct, but it may have some errors, given that I have tried to consolidate the info from quite a range of PDFs out there.

Thank you in advance for feedback.

Snapshots of sheets:

Preview of Sheet 1

Preview of Sheet 2

Preview of Sheet 3

Preview of Sheet 4

Preview of Sheet 5

Preview of Sheet 6

Spreadsheet Original for the above
( LibreOffice Spreadsheet )

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Please note that I will be “re-formatting” these guidance tables as HTML + CSS + JavaScript. The post what that “hard pivot” was communicated is found here, along with a tool for preserving the “time investment” by converting such an *.ods file into multiple HTML pages for each Tab/Sheet.

[Brian_Masinick]

Thank you @ericmarceau ; you have been preparing and sharing some REALLY good stuff! Much appreciated!

[ericmarceau]

Offering an update on my efforts for this project …

Following the “hard-turn” outlined in this other post, I invite members to access the sample revised documentation index page for the Forwarding Packet Flow, available from my GitHub repository, along with the single sample of a documentation page for the DROP target as relevant to raw state within the PREROUTING chain:

• Packet Destination Flow - Forwarding

• PRE_raw_t3.html

I am still in the early stages of trying to finalize the interraction/styling of the documentation. I look forward to insights, feedback or input into the documentation’s preparation.

Each table header and target cell is clickable to open an iframe with the applicable “Guidance” page.

Thank you in advance.

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Preview of Revised Look:

Forwarding

Incoming

Outgoing

**Preview of DROP guidance for raw within PREROUTING context**