Firewalld : IP Masquerade2023/02/20 |
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This is configration example of IP Masquerading on Firewalld.
This exmaple is based on the environment like follows.
Internet
-------------+-------------
Gateway|10.0.0.1
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External |
enp1s0|10.0.0.30
+------------+------------+
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| dlp.srv.world |
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+------------+------------+
enp7s0|192.168.0.30
Internal |
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| [1] | Change zones for interfaces. |
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# show current setting [root@dlp ~]# firewall-cmd --get-active-zone public interfaces: enp1s0 enp7s0 # change zone [root@dlp ~]# nmcli connection modify enp7s0 connection.zone internal [root@dlp ~]# nmcli connection modify enp1s0 connection.zone external
firewall-cmd --get-active-zone external interfaces: enp1s0 internal interfaces: enp7s0 |
| [2] | Set IP Masquerading on External zone. (if set permanently, add [--permanent] or [--runtime-to-permanent] option) |
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# set IP Masquerading [root@dlp ~]# firewall-cmd --zone=external --add-masquerade success # confirm setting [root@dlp ~]# firewall-cmd --zone=external --query-masquerade yes # [ip_forward] is enabled automatically if masquerading is enabled [root@dlp ~]# cat /proc/sys/net/ipv4/ip_forward 1 |
| [3] | For example, Configure that incoming packets come to 22 port of External zone are forwarded to local 1234 port. |
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[root@dlp ~]# firewall-cmd --zone=external --add-forward-port=port=22:proto=tcp:toport=1234 success [root@dlp ~]# firewall-cmd --list-all --zone=external
external (active)
target: default
icmp-block-inversion: no
interfaces: enp1s0
sources:
services: ssh
ports:
protocols:
forward: yes
masquerade: yes
forward-ports:
port=22:proto=tcp:toport=1234:toaddr=
source-ports:
icmp-blocks:
rich rules:
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| [4] | For example, Configure that incoming packets come to 22 port of External zone are forwarded to another Host [192.168.0.31] of 22 port. |
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[root@dlp ~]# firewall-cmd --zone=external --add-forward-port=port=22:proto=tcp:toport=22:toaddr=192.168.0.31 success [root@dlp ~]# firewall-cmd --list-all --zone=external
external (active)
target: default
icmp-block-inversion: no
interfaces: enp1s0
sources:
services: ssh
ports:
protocols:
forward: yes
masquerade: yes
forward-ports:
port=22:proto=tcp:toport=1234:toaddr=
port=22:proto=tcp:toport=22:toaddr=192.168.0.31
source-ports:
icmp-blocks:
rich rules:
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| [5] | For exmaple, Configure that outgoing packets through the Server from Internal network [192.168.0.0/24] are allowed and forwarded to the External side. |
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# set masquerading to internal zone [root@dlp ~]# firewall-cmd --zone=internal --add-masquerade success firewall-cmd --direct --add-rule ipv4 nat POSTROUTING 0 -o enp1s0 -j MASQUERADE [root@dlp ~]# firewall-cmd --direct --add-rule ipv4 filter FORWARD 0 -i enp7s0 -o enp1s0 -j ACCEPT [root@dlp ~]# firewall-cmd --direct --add-rule ipv4 filter FORWARD 0 -i enp1s0 -o enp7s0 -m state --state RELATED,ESTABLISHED -j ACCEPT |
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