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162 lines
5.4 KiB
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=============
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Using Aliases
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=============
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Aliases are named lists of networks, hosts or ports that can be used as one entity
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by selecting the alias name in the various supported sections of the firewall.
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These aliases are particularly useful to condense firewall rules and minimize
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changes.
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-----------
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Alias Types
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-----------
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OPNsense offers the following alias types:
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+------------+------------------------------------------------------+
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| Type | Description |
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+============+======================================================+
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| Hosts | Single hosts by IP or Fully Qualified Domain Name |
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+------------+------------------------------------------------------+
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| Networks | Entire network p.e. 192.168.1.1/24 |
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+------------+------------------------------------------------------+
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| Ports | Port numbers or a port range like 20:30 |
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+------------+------------------------------------------------------+
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| URL Tables | A table of IP addresses that can be fetched |
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+------------+------------------------------------------------------+
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| GeoIP | Select countries or whole regions |
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+------------+------------------------------------------------------+
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-----
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Hosts
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-----
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Hosts can be entered as a single IP address or a fully qualified domain name.
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When using a fully qualified domain name, the name will we resolved periodically
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(default is each 300 seconds).
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Sample
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Let's say we want to create an alias table for **www.youtube.com**
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.. image:: images/aliases_host.png
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:width: 100%
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**Apply changes** and look at the content of our newly created pf table.
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Go to **Firewall->Diagnostics->pfTables** and select our newly created youtube table.
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.. image:: images/pftable_youtube.png
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:width: 100%
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As you can see there are multiple IP addresses for this domain.
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--------
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Networks
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--------
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Networks are specified in Classless Inter-Domain Routing format (CIDR). Use the
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the correct CIDR mask for each entry. For instance a /32 specifies a single IPv4 host,
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or /128 specifies a single IPv6 host, whereas /24 specifies 255.255.255.0 and
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/64 specifies a normal IPv6 network.
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-----
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Ports
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-----
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Ports can be specified as a single number or a range using a colon **:**.
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For instance to add a range of 20 to 25 one would enter 20:25 in the **Port(s)**
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section.
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----------
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URL Tables
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----------
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URL tables can be used to fetch a list of IP addresses from a remote server.
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There are several IP lists available for free, most notably are the "Don't Route
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Or Peer" lists from Spamhaus.
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-----
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GeoIP
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-----
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With GeoIP alias you can select one or more countries or whole continents to block
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or allow. Use the *toggle all* checkbox to select all countries within the given
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region.
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This feature was reworked with 17.7.7 and supersedes the GeoIP blocking via IPS.
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.. image:: images/firewall_geoip_alias.png
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:width: 100%
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--------------
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Import Feature
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--------------
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To quickly add a list of aliases OPNsense also offers an import feature, where
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you can paste or enter a list in text format.
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Common examples are lists of IPs, networks, blacklists, etc.
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The list may contain IP addresses, with or without CIDR prefix, IP ranges,
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blank lines (ignored) and an optional description after each IP. e.g.:
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.. code::
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172.16.1.2
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172.16.0.0/24
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10.11.12.100-10.11.12.200
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192.168.1.254 Home router
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10.20.0.0/16 Office network
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10.40.1.10-10.40.1.19 Managed switches
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Spamhaus
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--------
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The Spamhaus Don't Route Or Peer Lists
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DROP (Don't Route Or Peer) and EDROP are advisory "drop all traffic" lists,
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consisting of netblocks that are "hijacked" or leased by professional spam or
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cyber-crime operations (used for dissemination of malware, trojan downloaders,
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botnet controllers). The DROP and EDROP lists are a tiny subset of the SBL,
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designed for use by firewalls and routing equipment to filter out the malicious
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traffic from these netblocks.
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*Source :* https://www.spamhaus.org/drop/
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Downloads
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* `DROP list <https://www.spamhaus.org/drop/drop.txt>`__
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* `EDROP list <https://www.spamhaus.org/drop/edrop.txt>`__
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----------------------------------
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Using Aliases in pf Firewall Rules
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----------------------------------
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Aliases can be used in the firewall rules to make administration of large lists
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easy. For instance we could have a list of remote IPs that should have access to
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certain services, when anything changes we only need to update the list.
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Let's create a simple alias list and assume we have 3 remote IPs that may access
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the ipsec server for a site to site tunnel connection:
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* 192.168.100.1
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* 192.168.200.2
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* 192.168.300.3
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.. image:: images/alias_remote_ipsec.png
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:width: 100%
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We call our list remote_ipsec and update our firewall rules accordingly.
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.. image:: images/alias_firewall_rules.png
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:width: 100%
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Notice the list icon to identify a rule with an alias (list).
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--------
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Advanced
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--------
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For hosts it is possible to use lists in lists. Per example you could have:
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* critical_servers {10.0.1.1 , 10.0.1.2}
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* other_servers {10.0.1.100 , 10.0.1.200}
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Then concatenate both by defining a new list:
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* servers { critical_servers , other_servers}.
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The end result will be a list with all IP addresses in one alias list (servers).
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------------------------------
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Configure DROP and EDROP lists
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------------------------------
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To setup the DROP and EDROP lists in combination with the firewall rules, read:
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:doc:`how-tos/edrop`
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