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So let's get back to the original state and use Firewall-D on CentOS.

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First I need systemctl unmask Firewall-D and then I can use systemctl enable –now Firewall-D.

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Then we need to do what? Well, we need Firewall-CMD –listall, which is a good start to figure out what is allowed.

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And we can see that SSH is already there. We don't have HTTP and NTP.

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So Firewall-CMD –get-services –pipe-grab-ntp.

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There you can see the name is just NTP, that makes it easy, and HTTP.

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We have different HTTPS, but the question is specifically about HTTP, right?

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So Firewall-CMD –add-service-ntp –permanent.

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As you can see, you may, but you don't have to, put an equal sign between the add-service and the NTP.

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And then same for HTTP and Firewall-CMD –reload.

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But then the incoming traffic from address 20.00.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.6 and is blocked.

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That is what you need to do using RIDS rules.

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Now, if you ever want to work with the RIDS rules, there are two components.

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First, Firewall-CMD. – minus –help-pipe-grab-RIDS

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will show you that there is add RIDS rule –equals and then you have the lugar rule.

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Man-K-RIDS is telling you Firewall-D.RIDS-language.

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And I'm going to have a look at Firewall-D.RIDS-language.

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That has language examples.

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Go all the way down and there you can find examples.

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And here we can see an example and I like this example,

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which is going to drop all connections from a specific IP address.

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I can work with that.

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So based on that, I'm going to use Firewall-CMD. – minus –add-RIDS-rule-is

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and then between single quotes, we put the rule.

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And of course, I need to modify the rule, but rule family is IPv4.

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That sounds good. Source address is, well, you should guess that 10.0.20.0

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is what was asked for. 20.0.0 slash 16.

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It should be acceptable and, yay, that is a success.

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Let's not forget to add that to permanent as well,

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because otherwise, it won't survive a restart of your firewall.

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Now Firewall-CMD– reload and Firewall-CMD–list

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all should show you all your current configuration,

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including the rich rule that was just added.

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And that is what was needed for this lab.