Firewalld : IP Masquerade2019/09/27 |
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This is configration example of IP Masquerading with Firewalld.
This exmaple is based on the environment like follows.
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Gateway|192.168.0.1
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External |
ens8|192.168.0.30
+------------+------------+
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| dlp.srv.world |
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+------------+------------+
ens2|10.0.0.30
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: ens2 ens8 # change zone [root@dlp ~]# nmcli connection modify ens2 connection.zone internal [root@dlp ~]# nmcli connection modify ens8 connection.zone external
firewall-cmd --get-active-zone external interfaces: ens8 internal interfaces: ens2 |
| [2] | Set IP Masquerading on External zone. |
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# set IP Masquerading [root@dlp ~]# firewall-cmd --zone=external --add-masquerade --permanent success [root@dlp ~]# firewall-cmd --reload success # show 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. (if set permanently, add [--permanent] option) |
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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: ens8 sources: services: ssh ports: protocols: masquerade: yes forward-ports: port=22:proto=tcp:toport=1234:toaddr= source-ports: icmp-blocks: rich rules: |
| [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: ens8 sources: services: ssh ports: protocols: masquerade: yes forward-ports: port=22:proto=tcp:toport=22:toaddr=192.168.0.31 source-ports: icmp-blocks: rich rules: |
| [5] | For exmaple, Configure that outgoing packets through the Server from Internal network [10.0.0.0/24] are allowed and forwarded to External side. |
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# set masquerading to internal zone [root@dlp ~]# firewall-cmd --zone=internal --add-masquerade --permanent success [root@dlp ~]# firewall-cmd --reload success firewall-cmd --direct --add-rule ipv4 nat POSTROUTING 0 -o ens8 -j MASQUERADE [root@dlp ~]# firewall-cmd --direct --add-rule ipv4 filter FORWARD 0 -i ens2 -o ens8 -j ACCEPT [root@dlp ~]# firewall-cmd --direct --add-rule ipv4 filter FORWARD 0 -i ens8 -o ens2 -m state --state RELATED,ESTABLISHED -j ACCEPT |
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