introduce fw-addr-lists

README.md

@@ -208,6 +208,7 @@ Available scripts
 * [Comment DHCP leases with info from access list](doc/dhcp-lease-comment.md)
 * [Create DNS records for DHCP leases](doc/dhcp-to-dns.md)
 * [Automatically upgrade firmware and reboot](doc/firmware-upgrade-reboot.md)
+* [Download, import and update firewall address-lists](doc/fw-addr-lists.md)
 * [Wait for global functions und modules](doc/global-wait.md)
 * [Send GPS position to server](doc/gps-track.md)
 * [Use WPA2 network with hotspot credentials](doc/hotspot-to-wpa.md)

doc/fw-addr-lists.md

@@ -0,0 +1,88 @@
+Download, import and update firewall address-lists
+==================================================
+
+[⬅️ Go back to main README](../README.md)
+
+> ℹ️ **Info**: This script can not be used on its own but requires the base
+> installation. See [main README](../README.md) for details.
+
+Description
+-----------
+
+This script downloads, imports and updates firewall address-lists. Its main
+purpose is to block attacking ip addresses, spam hosts, command-and-control
+servers and similar malicious entities. The default configuration contains
+a list from [dshield.org](https://dshield.org/).
+
+The address-lists are updated in place, so after initial import you will not
+see situation when the lists are not populated.
+
+To mitigate man-in-the-middle attacks with altered lists the server's
+certificate is checked.
+
+Requirements and installation
+-----------------------------
+
+Just install the script:
+
+    $ScriptInstallUpdate fw-addr-lists;
+
+And add two schedulers, first one for initial import after startup, second
+one for subsequent updates:
+
+    /system/scheduler/add name="fw-addr-lists@startup" start-time=startup on-event="/system/script/run fw-addr-lists;";
+    /system/scheduler/add name="fw-addr-lists" start-time=startup interval=2h on-event="/system/script/run fw-addr-lists;";
+
+> ℹ️ **Info**: Modify the interval to your needs, but it is recommended to
+> use less than half of the configured timeout for expiration.
+
+Configuration
+-------------
+
+The configuration goes to `global-config-overlay`, these are the parameters:
+
+* `FwAddrLists`: a list of firewall address-lists to download and import
+* `FwAddrListTimeOut`: the timeout for expiration without renew
+
+> ℹ️ **Info**: Copy relevant configuration from
+> [`global-config`](../global-config.rsc) (the one without `-overlay`) to
+> your local `global-config-overlay` and modify it to your specific needs.
+
+Naming a certificate for a list makes the script verify the server
+certificate, so you should add that if possible. Some certificates are
+available in my repository and downloaded automatically. Import it manually
+(menu `/certificate/`) if missing.
+
+Create firewall rules to process the packets that are related to addresses
+from address-lists. This rejects the packets from and to ip addresses listed
+in address-list `block`.
+
+    /ip/firewall/filter/add chain=input src-address-list=block action=reject reject-with=icmp-admin-prohibited;
+    /ip/firewall/filter/add chain=forward src-address-list=block action=reject reject-with=icmp-admin-prohibited;
+    /ip/firewall/filter/add chain=forward dst-address-list=block action=reject reject-with=icmp-admin-prohibited;
+    /ip/firewall/filter/add chain=output dst-address-list=block action=reject reject-with=icmp-admin-prohibited;
+
+You may want to have an address-list to allow specific addresses, as prepared
+with a list `allow`. In fact you can use any list name, just change the
+default ones or add your own - matching in configuration and firewall rules.
+
+    /ip/firewall/filter/add chain=input src-address-list=allow action=accept;
+    /ip/firewall/filter/add chain=forward src-address-list=allow action=accept;
+    /ip/firewall/filter/add chain=forward dst-address-list=allow action=accept;
+    /ip/firewall/filter/add chain=output dst-address-list=allow action=accept;
+
+Modify these for your needs, but **most important**: Move the rules up in
+chains and make sure they actually take effect as expected!
+
+Alternatively handle the packets in firewall's raw section if you prefer:
+
+    /ip/firewall/raw/add chain=prerouting src-address-list=block action=drop;
+    /ip/firewall/raw/add chain=prerouting dst-address-list=block action=drop;
+    /ip/firewall/raw/add chain=output dst-address-list=block action=drop;
+
+> ⚠️ **Warning**: Just again... The order of firewall rules is important. Make
+> sure they actually take effect as expected!
+
+---
+[⬅️ Go back to main README](../README.md)  
+[⬆️ Go back to top](#top)

fw-addr-lists.rsc

@@ -0,0 +1,99 @@
+#!rsc by RouterOS
+# RouterOS script: fw-addr-lists
+# Copyright (c) 2023 Christian Hesse <mail@eworm.de>
+# https://git.eworm.de/cgit/routeros-scripts/about/COPYING.md
+#
+# download, import and update firewall address-lists
+# https://git.eworm.de/cgit/routeros-scripts/about/doc/fw-addr-lists.md
+
+:local 0 "fw-addr-lists";
+:global GlobalFunctionsReady;
+:while ($GlobalFunctionsReady != true) do={ :delay 500ms; }
+
+:global FwAddrLists;
+:global FwAddrListTimeOut;
+
+:global CertificateAvailable;
+:global LogPrintExit2;
+:global ScriptLock;
+:global WaitFullyConnected;
+
+:local FindDelim do={
+  :local ValidChars "0123456789./";
+  :for I from=0 to=[ :len $1 ] do={
+    :if ([ :typeof [ :find $ValidChars [ :pick ($1 . " ") $I ] ] ] != "num") do={
+      :return $I;
+    }
+  }
+}
+
+$ScriptLock $0;
+
+$WaitFullyConnected;
+
+:local ListComment ("managed by " . $0);
+
+:foreach FwListName,FwList in=$FwAddrLists do={
+  :local Addresses ({});
+  :local CntAdd 0;
+  :local CntRenew 0;
+  :local CntRemove 0;
+  :local Failure false;
+
+  :foreach List in=$FwList do={
+    :local Data;
+    :local CheckCertificate "no";
+
+    :if ([ :len ($List->"cert") ] > 0) do={
+      :set CheckCertificate "yes-without-crl";
+      :if ([ $CertificateAvailable ($List->"cert") ] = false) do={
+        $LogPrintExit2 warning $0 ("Downloading required certificate failed, trying anyway.") false;
+      }
+    }
+
+    :do {
+      :set Data ([ /tool/fetch ($List->"url") check-certificate=$CheckCertificate output=user as-value ]->"data");
+    } on-error={
+      :set Failure true;
+      $LogPrintExit2 warning $0 ("Failed downloading list from: " . $List->"url") false;
+    }
+
+    :while ([ :len $Data ] != 0) do={
+      :local Line [ :pick $Data 0 [ :find $Data "\n" ] ];
+      :local Address ([ :pick $Line 0 [ $FindDelim $Line ] ] . ($List->"cidr"));
+      :if ($Address ~ "^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}(/[0-9]{1,2})?\$") do={
+        :set ($Addresses->$Address) 1;
+      }
+      :set Data [ :pick $Data ([ :len $Line ] + 1) [ :len $Data ] ];
+    }
+  }
+
+  :foreach Entry in=[ /ip/firewall/address-list/find where list=$FwListName comment=$ListComment ] do={
+    :local Address [ /ip/firewall/address-list/get $Entry address ];
+    :if (($Addresses->$Address) = 1) do={
+      $LogPrintExit2 debug $0 ("Renewing: " . $Address) false;
+      /ip/firewall/address-list/set $Entry timeout=$FwAddrListTimeOut;
+      :set ($Addresses->$Address);
+      :set CntRenew ($CntRenew + 1);
+    } else={
+      :if ($Failure = false) do={
+        $LogPrintExit2 debug $0 ("Removing: " . $Address) false;
+        /ip/firewall/address-list/remove $Entry;
+        :set CntRemove ($CntRemove + 1);
+      }
+    }
+  }
+
+  :foreach Address,Ignore in=$Addresses do={
+    $LogPrintExit2 debug $0 ("Adding: " . $Address) false;
+    :do {
+      /ip/firewall/address-list/add list=$FwListName comment=$ListComment address=$Address timeout=$FwAddrListTimeOut;
+      :set ($Addresses->$Address);
+      :set CntAdd ($CntAdd + 1);
+    } on-error={
+      $LogPrintExit2 warning $0 ("Failed to add address " . $Address . " to list '" . $FwListName . "'.") false;
+    }
+  }
+
+  $LogPrintExit2 info $0 ("List: " . $FwListName . " -- Added: " . $CntAdd . " - renewed: " . $CntRenew . " - removed: " . $CntRemove) false;
+}

global-config.rsc

@@ -80,6 +80,21 @@
 :global BackupUploadUser "mikrotik";
 :global BackupUploadPass "v3ry-s3cr3t";
 
+# This defines the settings for firewall address-lists (fw-addr-lists).
+:global FwAddrLists {
+#  "allow"={
+#    { url="https://eworm.de/ros/fw-addr-lists/allow";
+#      cert="R3" };
+#  };
+  "block"={
+#    { url="https://eworm.de/ros/fw-addr-lists/block";
+#      cert="R3" };
+    { url="https://www.dshield.org/block.txt"; cidr="/24";
+      cert="R3" };
+  };
+};
+:global FwAddrListTimeOut 1d;
+
 # This defines what log messages to filter or include by topic or message
 # text. Regular expressions are supported. Do *NOT* set an empty string,
 # that will filter or include everything!

global-functions.rsc

@@ -12,7 +12,7 @@
 :local 0 "global-functions";
 
 # expected configuration version
-:global ExpectedConfigVersion 100;
+:global ExpectedConfigVersion 101;
 
 # global variables not to be changed by user
 :global GlobalFunctionsReady false;

news-and-changes.rsc

@@ -14,6 +14,7 @@
   98="Extended 'check-certificates' to download new certificate by SubjectAltNames if download by CommonName fails.";
   99="Modified 'dhcp-to-dns', which dropped global configuration. Settings moved to dhcp server's network definitions.";
   100="The script 'ssh-keys-import' became a module 'mod/ssh-keys-import' with enhanced functionality.";
+  101="Introduced new script 'fw-addr-lists' to download, import and update firewall address-lists.";
 };
 
 # Migration steps to be applied on script updates