[CentOS] Stupid C7 firewall question

Thu Oct 25 15:04:10 UTC 2018
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On 10/25/18 2:41 AM, Warren Young wrote:
> On Oct 24, 2018, at 8:06 PM, Joel Freeman <joel at joelazot.xyz> wrote:
>> Is there any reason to use Firewalld over IPTables?
> Lots: https://firewalld.org/
>> I'm incredibly new to Linux administration
> Given that, which would you rather type:
>      $ sudo firewall-cmd --add-service=ftp
> or whatever that does under the hood, which probably resembles the 7 commands given here:
>      https://unix.stackexchange.com/a/93555/138
> The commands given will only take effect while the system runs, so to make them permanent, you have to edit `/etc/sysconfig/iptables` with a somewhat different syntax.
> Contrast FirewallD, where you just re-issue the command above with a single additional flag:
>      $ sudo firewall-cmd --add-service=ftp --permanent
> FTP is an uncommonly difficult case, but direct iptables manipulation remains more difficult even in the single-port case.
> FirewallD doesn’t require that you use predefined services, either.  It works just fine with raw port numbers:
>      $ sudo firewall-cmd --add-port=50000/tcp
> Contrast the equivalent iptables command:
>      $ sudo iptables -A INPUT -p tcp --dport 50000 -j ACCEPT
> …and that only works if inserting into the INPUT chain is what you actually want to do, which it might not be on a system managed by FirewallD, which probably set up some more complicated chain scheme you’d have to understand in order to get the expected behavior.
> Why not let FirewallD handle all of that for you?
> I don’t miss direct iptables manipulation.

Thanks Warren for nice quick start covering everything one needs to 
configure firewalld. There is one thing I am related to "direct iptables 
manipulation" which is: suppose I made configuration of some machine, 
which then I am going to replicate just by using kickstart when building 
new machines. What should I add to kickstart configuration file to make 
my configured firewalld part reproduced on all newly built machines?

Thanks again!


PS Your quick startup reminds me how we were introducing UNIX (shell) to 
new users: basically we were showing them a handful of commands (5-10) 
with which person can start, and knowing which person can start doing 
what one needs. Bottom line: it takes 5-10 minutes to start using UNIX, 
no need to read 1000 page book before starting. I have exactly the same 
feeling after your introduction into firewalld - (except kickstart 
missing for me).

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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247