Iptables: Difference between revisions
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#REDIRECT [[IPTables]] |
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__NOTOC__ |
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= iptables = |
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== Howto setup iptagles on CentOS/Fedora == |
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Rules are always read from /etc/sysconfig/iptables, but if any "save" option is enable in /etc/sysconfig/iptables, the rules added from the command line are keep in memory, but won't be available on system reboot. |
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It happens in Fedora that rules in /etc/sysconfig/iptables are overriden until iptables daemon is restarted. |
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To make the system load our rules on reboot and everytime, you must ensure the rules that /etc/iptables.rules file does exist, an has the rules you just created. |
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== How to setup iptables on GNU/Debian == |
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Flush tables |
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== Setup a gateway with 2 Virtual NICs == |
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For any given host with 2 virtual NICs (alias IP) the steps to setup the host as gateway are: |
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Let say: |
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<pre><nowiki> |
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- WAN = eth0 -> 10.11.12.10 |
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- LAN = eth0:1 -> 192.168.10.10 |
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</nowiki></pre> |
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# Add to iptables the proper nat rules in order to ensure SNAT through the "Out to the world" NIC. |
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<pre><nowiki> |
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*nat |
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:PREROUTING ACCEPT [891:110412] |
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:POSTROUTING ACCEPT [92:11129] |
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:OUTPUT ACCEPT [241:27547] |
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-A POSTROUTING -o eth0 -j MASQUERADE |
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-A POSTROUTING -o eth0 -j SNAT --to-source 10.11.12.10 |
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COMMIT |
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</nowiki></pre> |
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# Because both network IPs are in the same NIC, then add to the filter section a forward in both directions: |
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<pre><nowiki> |
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-A FORWARD -i eth0 -j ACCEPT |
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-A FORWARD -o eth0 -j ACCEPT |
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</nowiki></pre> |
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# Ensure ip forwarding on kernel by setting the proper parameter to "1" in /etc/sysctl |
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<pre><nowiki> |
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net.ipv4.ip_forward = 1 |
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</nowiki></pre> |
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# Load the previous modification: |
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<pre><nowiki> |
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sysctl -p |
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</nowiki></pre> |
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Latest revision as of 22:04, 11 June 2015
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