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Old 06-30-2019, 12:16 AM   #1
Registered: Mar 2019
Posts: 188

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router, tor, i2p and iptables

Hello all, in an effort to help work on my security of my machine I am learning about IPtables and have a few questions. I have wrote a rules list for my setup (I got some from a guide and others from docs) which can be found here: (it's just big and I feel like it'd take too much space on the post). I have added rules for eth0 and iwn0 (my wifi, but I actually may need to script around this for portability. Like write this so that I can pass in my wifi interface), and I am feeling pretty good about it. Just one thing, I like to use tor and i2p for privacy reasons and wanted to ask how do I allow those? Along with that I know for DNS I need to accommodate my router (such as):

-A INPUT -i ens3 -s -p udp --sport 53 -m state --state ESTABLISHED,RELATED -j ACCEPT
-A OUTPUT -o ens3 -d -p udp --dport 53 -m udp -j ACCEPT
what if I don't know my router ip? I ask because A) I don't and I am not allowed to access that info (I am a teenager and that is a whole big thing for some reason) and B) this is on my laptop and if I travel I need to accommodate. If I leave this out does DNS work? IE if I don't disallow it it works? The issue is I have

and really would like to keep it (so no it wouldn't work if I left it out). How would I work with this?

My second question is in relation to SSH. I, being on a laptop, don't want or need to be able to ssh into this machine what would be the proper configuration for this? All I can find are things like this:

# Input
-A INPUT -i ens3 -p tcp -m state --state NEW,ESTABLISHED --dport 22 -j ACCEPT
-A OUTPUT -o ens3 -p tcp -m state --state ESTABLISHED --sport 22 -j ACCEPT
# Output
-A OUTPUT -o ens3 -p tcp -m state --state NEW,ESTABLISHED --dport 22 -j ACCEPT
-A INPUT -i ens3 -p tcp -m state --state ESTABLISHED --sport 22 -j ACCEPT
now to me I imagine I just disallow (remove) rules for input, is this right? Also does ens3 get replaced with Eth0/wifi card? I have never seen that before (pulled off an example a few hours ago).

Also any good recommendations for running iptables automatically?
Old 06-30-2019, 03:18 AM   #2
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Registered: Jun 2019
Posts: 16

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IDK but you should know that Iptables is getting phased out by Nftables and BPF.. With the latter being the best, cause BSD uses it and so does Pfsense (and it just recently got implemented into the Linux kernel). BPF has a much cleaner syntax..

Last edited by battlestationX; 06-30-2019 at 03:20 AM.
Old 07-13-2019, 07:13 PM   #3
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Registered: Feb 2003
Location: CT
Distribution: Debian 6+, CentOS 5+
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Well as far as not needing to ssh into the laptop just make sure you don't have the ssh server package installed. If it's not installed and not running blocked or not it's not a threat. Also it is easiest to use your chain and block everything then only open what you need.


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