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Document dedicated OSSEC iptables chain for firewall-drop. #356

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Merged
atomicturtle merged 1 commit into from
Aug 4, 2026
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Document dedicated OSSEC iptables chain for firewall-drop. #356

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2 changes: 1 addition & 1 deletion docs/manual/ar/ar-scripts.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ Firewall and network blocking
| Script | Expect | Notes |
+===================+==========+===============================================+
| host-deny.sh | srcip | Adds IP to ``/etc/hosts.deny`` (tcp wrappers) |
| firewall-drop.sh | srcip | iptables, ipfilter, or AIX IPSec (auto-detect)|
| firewall-drop.sh | srcip | iptables ``OSSEC`` chain, ipfilter, AIX IPSec |
| firewalld-drop.sh | srcip | Linux with firewalld; enable manually |
| nftables-drop.sh | srcip | Linux nftables; requires pre-configured sets |
| pf.sh | srcip | OpenBSD/FreeBSD PF table ``ossec_fwtable`` |
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11 changes: 10 additions & 1 deletion docs/manual/ar/ar-unix.rst
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Expand Up @@ -80,10 +80,19 @@ By default, the ossec hids comes with the following pre-configured
active-response tools:

- **host-deny.sh**: Adds an IP to the /etc/hosts.deny file (most Unix systems).
- **firewall-drop.sh** (iptables): Adds an IP to the iptables deny list (Linux 2.4 and 2.6).
- **firewall-drop.sh** (iptables): Adds an IP to a dedicated ``OSSEC`` iptables chain (Linux).
- **firewall-drop.sh** (ipfilter): Adds an IP to the ipfilter deny list (FreeBSD, NetBSD and Solaris).
- **firewall-drop.sh** (ipfw): Adds an IP to the ipfw deny table (FreeBSD).

.. note::

On iptables, drops go into chain ``OSSEC`` (created on first use) with a
jump from ``INPUT`` and, when IP forwarding is enabled, ``FORWARD``.
That keeps active-response blocks out of the main filter chains so
configuration-management tools that purge unmanaged rules are less
likely to remove them. Override the chain name with the
``OSSEC_FW_CHAIN`` environment variable if needed.

.. note::

On IPFW we use the table 1 to add the IPs to be blocked. We also
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