Skip to main content

Iptables - Firewall for Linux



Let's briefly look at some virtual firewalls in Linux. This is Iptables, running in my Ubuntu Server. Remember that?




What is CHAIN in this context? My best guess is 'the route a packet takes'. Think "At this point in the process, what should happen to this packet?" [1] Here, it's saying "Forward everything!". At which point, you may as well not have a firewall at all.



So let's set some rules on this bad boy;






The command is going 'super user within iptables, append the INPUT chain regarding the protocol tcp'


Let's try it with the example at the second link;



lo = Loopback
j = target, which must be set with each new rule. After all, how will iptables know to ACCEPT or DROP, RETURN?
So, that first rule isn't 'set' without it. Let's try it again;




Today I was reminded that Cases Matter.

Now we're looking good! Let's save them with sudo /sbin/iptables-save. I added a few more rules to this, namely DROP this CERTAIN connection, without saving.

There is plenty more information at the above links, so check them out, and I'll be revisiting more Linux and open source firewalls in the future.




Educate others -

Comments

Popular posts from this blog

What Do You Need? [AKA; List of Offered Services / My Next Role] (2020)

I am a trusted outsourced remote consultant for your company.   I enjoy having the flexibility to take on temporary projects from time to time! I start at part-time, temp work for now. If we like each other, we can renegotiate. If anything sounds weird, out there, or unusual - Feel free to e-mail me .  3 Services Offered Writing :      You want to pay me to write more of *waves hand* this blog? I am game .     I write B2C e-mails going out to over 280 people weekly. [ Example Job Description ]        Auditing :        Something doesn't work on your page. I can find it, or you can lose business. [ Here ] [ Example Job Description ]   Technical: Still as-needed, always remote, contract, or temporary. IT Operations Tech [ Example Job Description ]     Hardware and SaaS support.     Cisco routing and switching (Networking). CCNA, A+, Sec+, Azure certified WORKING ON: Junos Networking Cloud Technician     Azure [ See tag ]  Support [Web: Example Job Description ] [Text : Example

Portfolio of UX/Product Feedback [Vol. 1]

Have You Looked at Your Webpage From the Customer's View Lately? You have probably been linked here from a form or my resume. If you have any questions about what I'm looking for in a role, click here .   This post is not to shame, but to point out errors and hopefully make my talent for finding and documenting such mistakes clear to someone hiring. Contents: Instances where I offer constructive feedback on someone's website, logo, or app. Actions that were taken by the developers or artists.  I'm glad you want your webpages to be the best they can be with my help; If you need your sites audited, e-mail me . Latest Update -  November 20th, 2020.   Vol. 2 is here .

Wireless Diagnostics on Mac OS; Packet Sniffing on a WLAN

There's a post sitting in my drafts about Wireshark and how to sniff packets out of the air that was going to be about sniffing for authentication packets for Wi-Fi hotspots that aren't broadcasting SSID (Which you shouldn't do apparently! It's still not safe). I was watching this video to find a little more information about how to properly use Monitoring mode on my Macbook to sniff for WLAN packets on the network. So when he said "Just open up Wireless Diagnostics and sniff your network (check your width and channel)." It was shocking to me.