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today I was just doing regular maintenance on my computer and while checking that iptables was working properly I decided to run the list command,I was expecting to find my regular configuration dropping input and forward by default and accepting all outgoing traffic with some rules for input in order to allow browsing etc, however this is what the command listed iptables -L output, I am no expert so I am not sure of what all of these rules are doing, I recently updated to a newer version of ubuntu, is my computer compromised or this some change that was made by canonical.

Any help is appreciated thank you in advance!.

Edit: Currently I am using Ubuntu 18.04 64-bit, the desktop version, and I am not using virtualization, iptables v1.6.1, and the Kernel version is 5.5.7 hope this helps

Edit 2: Ok so I feel pretty dumb right now, after the upgrade it seems that the installer flushed my iptables configuration and activated UFW aka the regular firewall, since the firewall has multiple set ups it creates a bunch of rules that are listed under iptables regardless of which one is being used, I just needed to turn of the firewall and set my normal rules, Thanks to the guy who commented.

Miguel Garcia
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  • To start with, which version of Linux have you installed  (Ubuntu server, Ubuntu desktop, Kubuntu, Lubuntu, Xubuntu, Ubuntu MATE, et al.) , and which release number? Are you using virtualization, and if so, which package? Different releases have different tools for us to recommend. Please click [edit] and add that vital information to your question so all the facts we need are in the question. Please don't use Add Comment, since that's our channel to you. All facts about your system should go in the Question with [edit] – K7AAY Apr 06 '20 at 22:29

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Since you haven't listed the verbose output, I can't be certain, but it looks like it is not accepting input traffic as a default.

Your settings are being applied by the ufw service, you can see more info with ufw status, or full iptables output of the filter table with iptables -vnL --line-numbers.

There is also ip6tables for ipv6 related rules.

You can see what ports your computing is listening on with ss -nlptu

You can use nmap from another computer to test your firewall rules, for example nmap -Pn -A <ip_address>

ThankYee
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  • Also see this answer about getting your firewall rules to work like the good old days: https://askubuntu.com/a/1072948/853283 – ThankYee Apr 13 '20 at 05:25