Re: [PATCH] (V4) Forcing DNS/NTP

[Matthias Fischer <matthias.fischer@ipfire.org>]

[-- Attachment #1: Type: text/plain, Size: 30867 bytes --]

Hi,

On 06.06.2021 10:59, Bernhard Bitsch wrote:
> Hi,
> 
> thanks for implementing this idea.

I tried my best, but when reading further I realized that I've missed
something... See below.

[Sorry for the noise, but I thought it would be the best to keep this
unshortened.]

> Am 04.06.2021 um 14:17 schrieb Matthias Fischer:
>> There was not much feedback on the list, so I send this now. This is V4 - open for
>> discussion, opinions or (perhaps ;-) ) changes:
>> 
>> Originally triggered by:
>> https://community.ipfire.org/t/forcing-all-dns-traffic-from-the-lan-to-the-firewall/3512
>> 
>> Discussion:
>> https://community.ipfire.org/t/testing-dns-redirect-code-snippet/3888
>> 
>> Could fix(?):
>> https://bugzilla.ipfire.org/show_bug.cgi?id=11168
>> 
>> Changelog since V3:
>> 
>> - Replaced 'green0'/'blue0' with '${GREEN_DEV}' / '${BLUE_DEV}' - these
>>    values are read from '/var/ipfire/ethernet/settings', thanks
>>    to "someone" for the hint (sorry, I didn't find the author)! ;-)
>> 
>> - Replaced port numbers '123' / '53' with service names 'domain' / 'ntp' (dto.).
>> 
>> - As mentioned on the list (05.03.2021, BB), 'well-behaving' requests are now
>>    handled through RETURN rules, others through REDIRECT.
>> 
>> Background (cited from BB, 06.03.2021):
>> "Concerning performance, we want to minimize the rule set to the amount
>> really necessary. On the other hand, it may be quicker to do just
>> a RETURN than a REDIRECT. The cases for the RETURN (DNS requests direct
>> to IPFire) should be nearly 100%. DNS and NTP servers are published
>> by DHCP or should be configured in the static case."
>> 
> 
> Sorry, I did not realize that this 'well-behaving' must be defined more 
> exactly. See beyond.

Yep. No problem. Now I know what you meant.
And again, "see beyond"... ;-)

>> I made it that way. Statistics during the last 62 days show that this
>> worked as intended. IMHO. I've sent a screenshot to the list (the other day) so
>> everyone could take a look.
>> 
> 
> That's my experience with the rules located in firewall.local, too.
> 
>> - Removed GUI links to DNS and NTP options in 'optionsfw.cgi'.
>> 
>> - Moved creation of the iptable rules in '/etc/init.d/firewall' behind
>> '# WIRELESS chains'
>> 
>> Summary and functionality:
>>    These patches are controlled through "Firewall Options". They add new
>>    firewall-[DNS/NTP]_FORCED_ON_[INTERFACE]-options to '/var/ipfire/optionsfw/settings'.
>>    They activate/deactivate appropriate RETURN and REDIRECT rules through
>>    a new ctrl file ('/usr/local/bin/dnsntpctrl') and a new init file
>>    ('/etc/rc.d/init.d/dnsntp').
>> 
>>    Default of all new rules is OFF (set in 'lfs/configroot').
>>    If set to ON, they REDIRECT all DNS and NTP requests (TCP/UDP) to the DNS and NTP
>>    servers specified in IPFire.
>> 
>>    Flaw/ToDo:
>>    To make things work as I wanted I had to add a 'dnsntpctrl' file which calls the actual
>>    init file, 'dnsntp'. As I see it, this is actually an unnecessary detour.
>>    In fact I wanted to merge these two files in *one* C file, but this was beyond my
>>    capabilities, perhaps "someone" else knows how to program this.
>> 
>> Changed visibility (GUI, 'optionsfw.cgi') and some cosmetics:
>>    The corresponding interface options - including 'Masquerade ...' - are only visible if
>>    the respective interface actually exists.
>>    E.g.: if BLUE interface doesn't exist, there are no ON/OFF switches
>>    for 'DNS/NTP on BLUE' or logging options for BLUE available.
>>    Added text colors for better readability.
>>    Separated logging options per interface.
>> 
>> No reboot required:
>>    Rules can be switched ON/OFF without rebooting IPFire.
>>    Changes immedediately take effect after clicking 'Save'.
>> 
>> Changes to '/etc/rc.d/init.d/firewall' and '/etc/rc.d/init.d/dnsntpctrl':
>>    Fixed a 'trafic' typo.
>>    To avoid collisions with existing CUSTOM rules, I added a new PREROUTING
>>    chain: 'DNS_NTP_REDIRECT'.
>>    This chain is flushed by 'dnsntpctrl' prior applying the choosen settings.
>> 
>> Signed-off-by: Matthias Fischer <matthias.fischer(a)ipfire.org>
>> ---
>>   config/rootfiles/common/misc-progs |  1 +
>>   html/cgi-bin/optionsfw.cgi         | 90 ++++++++++++++++++++++++------
>>   langs/de/cgi-bin/de.pl             | 15 +++--
>>   langs/en/cgi-bin/en.pl             | 15 +++--
>>   lfs/configroot                     |  6 +-
>>   src/initscripts/system/dnsntp      | 43 ++++++++++++++
>>   src/initscripts/system/firewall    |  9 ++-
>>   src/misc-progs/Makefile            |  2 +-
>>   src/misc-progs/dnsntpctrl.c        | 19 +++++++
>>   9 files changed, 171 insertions(+), 29 deletions(-)
>>   create mode 100644 src/initscripts/system/dnsntp
>>   create mode 100644 src/misc-progs/dnsntpctrl.c
>> 
>> diff --git a/config/rootfiles/common/misc-progs b/config/rootfiles/common/misc-progs
>> index d6594b3f8..4bcb94812 100644
>> --- a/config/rootfiles/common/misc-progs
>> +++ b/config/rootfiles/common/misc-progs
>> @@ -5,6 +5,7 @@ usr/local/bin/captivectrl
>>   usr/local/bin/collectdctrl
>>   usr/local/bin/ddnsctrl
>>   usr/local/bin/dhcpctrl
>> +usr/local/bin/dnsntpctrl
>>   usr/local/bin/extrahdctrl
>>   usr/local/bin/fireinfoctrl
>>   usr/local/bin/firewallctrl
>> diff --git a/html/cgi-bin/optionsfw.cgi b/html/cgi-bin/optionsfw.cgi
>> index 321642e82..2059a03b3 100644
>> --- a/html/cgi-bin/optionsfw.cgi
>> +++ b/html/cgi-bin/optionsfw.cgi
>> @@ -50,6 +50,7 @@ if ($settings{'ACTION'} eq $Lang::tr{'save'}) {
>>   		$errormessage .= $Lang::tr{'new optionsfw later'};
>>   		&General::writehash($filename, \%settings);             # Save good settings
>>   		system("/usr/local/bin/firewallctrl");
>> +		system("/usr/local/bin/dnsntpctrl >/dev/null 2>&1");
>>   	}else{
>>   		if ($settings{'POLICY'} ne ''){
>>   			$fwdfwsettings{'POLICY'} = $settings{'POLICY'};
>> @@ -65,6 +66,7 @@ if ($settings{'ACTION'} eq $Lang::tr{'save'}) {
>>   		&General::writehash("${General::swroot}/firewall/settings", \%fwdfwsettings);
>>   		&General::readhash("${General::swroot}/firewall/settings", \%fwdfwsettings);
>>   		system("/usr/local/bin/firewallctrl");
>> +		system("/usr/local/bin/dnsntpctrl >/dev/null 2>&1");
>>   	}
>>   	&General::readhash($filename, \%settings);             # Load good settings
>>   }
>> @@ -140,6 +142,18 @@ $selected{'MASQUERADE_ORANGE'}{$settings{'MASQUERADE_ORANGE'}} = 'selected="sele
>>   $selected{'MASQUERADE_BLUE'}{'off'} = '';
>>   $selected{'MASQUERADE_BLUE'}{'on'} = '';
>>   $selected{'MASQUERADE_BLUE'}{$settings{'MASQUERADE_BLUE'}} = 'selected="selected"';
>> +$checked{'DNS_FORCE_ON_GREEN'}{'off'} = '';
>> +$checked{'DNS_FORCE_ON_GREEN'}{'on'} = '';
>> +$checked{'DNS_FORCE_ON_GREEN'}{$settings{'DNS_FORCE_ON_GREEN'}} = "checked='checked'";
>> +$checked{'DNS_FORCE_ON_BLUE'}{'off'} = '';
>> +$checked{'DNS_FORCE_ON_BLUE'}{'on'} = '';
>> +$checked{'DNS_FORCE_ON_BLUE'}{$settings{'DNS_FORCE_ON_BLUE'}} = "checked='checked'";
>> +$checked{'NTP_FORCE_ON_GREEN'}{'off'} = '';
>> +$checked{'NTP_FORCE_ON_GREEN'}{'on'} = '';
>> +$checked{'NTP_FORCE_ON_GREEN'}{$settings{'NTP_FORCE_ON_GREEN'}} = "checked='checked'";
>> +$checked{'NTP_FORCE_ON_BLUE'}{'off'} = '';
>> +$checked{'NTP_FORCE_ON_BLUE'}{'on'} = '';
>> +$checked{'NTP_FORCE_ON_BLUE'}{$settings{'NTP_FORCE_ON_BLUE'}} = "checked='checked'";
>>   
>>   &Header::openbox('100%', 'center',);
>>   print "<form method='post' action='$ENV{'SCRIPT_NAME'}'>";
>> @@ -189,13 +203,44 @@ END
>>   END
>>   	}
>>   
>> -	print <<END
>> +print <<END;
>> +	<table width='95%' cellspacing='0'>
>> +		<tr bgcolor='$color{'color20'}'></tr>
>> +		<tr>&nbsp;</tr>
>> +			<td colspan='2' align='left'><b>$Lang::tr{'fw green'}</b></td>
>> +		</tr>
>> +		<tr><td align='left' width='60%'>$Lang::tr{'dns force on green'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DNS_FORCE_ON_GREEN' value='on' $checked{'DNS_FORCE_ON_GREEN'}{'on'} />/
>> +																						<input type='radio' name='DNS_FORCE_ON_GREEN' value='off' $checked{'DNS_FORCE_ON_GREEN'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +		<tr><td align='left' width='60%'>$Lang::tr{'ntp force on green'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='NTP_FORCE_ON_GREEN' value='on' $checked{'NTP_FORCE_ON_GREEN'}{'on'} />/
>> +																						<input type='radio' name='NTP_FORCE_ON_GREEN' value='off' $checked{'NTP_FORCE_ON_GREEN'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +END
>> +
>> +	if (&Header::blue_used()) {
>> +		print <<END;
>> +		<table width='95%' cellspacing='0'>
>> +		<tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw blue'}</b></td></tr>
>> +		<tr>&nbsp;</tr>
>> +			<tr>
>> +			<tr><td align='left' width='60%'>$Lang::tr{'dns force on blue'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DNS_FORCE_ON_BLUE' value='on' $checked{'DNS_FORCE_ON_BLUE'}{'on'} />/
>> +																						<input type='radio' name='DNS_FORCE_ON_BLUE' value='off' $checked{'DNS_FORCE_ON_BLUE'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +			<tr><td align='left' width='60%'>$Lang::tr{'ntp force on blue'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='NTP_FORCE_ON_BLUE' value='on' $checked{'NTP_FORCE_ON_BLUE'}{'on'} />/
>> +																						<input type='radio' name='NTP_FORCE_ON_BLUE' value='off' $checked{'NTP_FORCE_ON_BLUE'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +			<tr><td align='left' width='60%'>$Lang::tr{'drop proxy'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPPROXY' value='on' $checked{'DROPPROXY'}{'on'} />/
>> +																						<input type='radio' name='DROPPROXY' value='off' $checked{'DROPPROXY'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +			<tr><td align='left' width='60%'>$Lang::tr{'drop samba'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPSAMBA' value='on' $checked{'DROPSAMBA'}{'on'} />/
>> +																						<input type='radio' name='DROPSAMBA' value='off' $checked{'DROPSAMBA'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> +			</td>
>> +			</tr>
>> +END
>> +	}
>> +
>> +	print <<END;
>>   	</table>
>>   
>> -	<br>
>> +	<br />
>>   
>> -<table width='95%' cellspacing='0'>
>> -<tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw logging'}</b></td></tr>
>> +		<table width='95%' cellspacing='0'>
>> +<tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw logging red'}</b></td></tr>
>>   <tr><td align='left' width='60%'>$Lang::tr{'drop newnotsyn'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPNEWNOTSYN' value='on' $checked{'DROPNEWNOTSYN'}{'on'} />/
>>   																						<input type='radio' name='DROPNEWNOTSYN' value='off' $checked{'DROPNEWNOTSYN'}{'off'} /> $Lang::tr{'off'}</td></tr>
>>   <tr><td align='left' width='60%'>$Lang::tr{'drop input'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPINPUT' value='on' $checked{'DROPINPUT'}{'on'} />/
>> @@ -206,21 +251,30 @@ END
>>   																						<input type='radio' name='DROPOUTGOING' value='off' $checked{'DROPOUTGOING'}{'off'} /> $Lang::tr{'off'}</td></tr>
>>   <tr><td align='left' width='60%'>$Lang::tr{'drop portscan'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPPORTSCAN' value='on' $checked{'DROPPORTSCAN'}{'on'} />/
>>   																						<input type='radio' name='DROPPORTSCAN' value='off' $checked{'DROPPORTSCAN'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> -<tr><td align='left' width='60%'>$Lang::tr{'drop wirelessinput'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPWIRELESSINPUT' value='on' $checked{'DROPWIRELESSINPUT'}{'on'} />/
>> +END
>> +
>> +	if (&Header::blue_used()) {
>> +		print <<END;
>> +	</table>
>> +
>> +	<br />
>> +
>> +		<table width='95%' cellspacing='0'>
>> +<tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw logging blue'}</b></td></tr>
>> +			<tr>
>> +			<tr><td align='left' width='60%'>$Lang::tr{'drop wirelessinput'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPWIRELESSINPUT' value='on' $checked{'DROPWIRELESSINPUT'}{'on'} />/
>>   																						<input type='radio' name='DROPWIRELESSINPUT' value='off' $checked{'DROPWIRELESSINPUT'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> -<tr><td align='left' width='60%'>$Lang::tr{'drop wirelessforward'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPWIRELESSFORWARD' value='on' $checked{'DROPWIRELESSFORWARD'}{'on'} />/
>> +			<tr><td align='left' width='60%'>$Lang::tr{'drop wirelessforward'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPWIRELESSFORWARD' value='on' $checked{'DROPWIRELESSFORWARD'}{'on'} />/
>>   																						<input type='radio' name='DROPWIRELESSFORWARD' value='off' $checked{'DROPWIRELESSFORWARD'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> -</table>
>> -<br/>
>> +			</tr>
>> +END
>> +	}
>> +
>> +	print <<END;
>> +	</table>
>> +
>> +	<br />
>>   
>> -<table width='95%' cellspacing='0'>
>> -<tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw blue'}</b></td></tr>
>> -<tr><td align='left' width='60%'>$Lang::tr{'drop proxy'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPPROXY' value='on' $checked{'DROPPROXY'}{'on'} />/
>> -																						<input type='radio' name='DROPPROXY' value='off' $checked{'DROPPROXY'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> -<tr><td align='left' width='60%'>$Lang::tr{'drop samba'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='DROPSAMBA' value='on' $checked{'DROPSAMBA'}{'on'} />/
>> -																						<input type='radio' name='DROPSAMBA' value='off' $checked{'DROPSAMBA'}{'off'} /> $Lang::tr{'off'}</td></tr>
>> -</table>
>> -<br>
>>   <table width='95%' cellspacing='0'>
>>   <tr bgcolor='$color{'color20'}'><td colspan='2' align='left'><b>$Lang::tr{'fw settings'}</b></td></tr>
>>   <tr><td align='left' width='60%'>$Lang::tr{'fw settings color'}</td><td align='left'>$Lang::tr{'on'} <input type='radio' name='SHOWCOLORS' value='on' $checked{'SHOWCOLORS'}{'on'} />/
>> @@ -252,7 +306,7 @@ END
>>   
>>   <br />
>>   <table width='100%' cellspacing='0'>
>> -<tr><td align='right'><form method='post' action='$ENV{'SCRIPT_NAME'}'>
>> +<tr><td align='center'><form method='post' action='$ENV{'SCRIPT_NAME'}'>
>>   <input type='submit' name='ACTION' value='$Lang::tr{'save'}' />
>>   </form></td></tr>
>>   </table>
>> @@ -278,7 +332,7 @@ print <<END;
>>   	    <input type='submit' name='ACTION' value='$Lang::tr{'save'}' /><input type='hidden' name='defpol' value='1'></td>
>>   END
>>   	print "</tr></table></form>";
>> -	print"<br><br>";
>> +	print"<br /><br />";
>>   	print <<END;
>>   	<form method='post' action='$ENV{'SCRIPT_NAME'}'>
>>   	<table width='100%' border='0'>
>> diff --git a/langs/de/cgi-bin/de.pl b/langs/de/cgi-bin/de.pl
>> index 0bc579cd2..51e65b903 100644
>> --- a/langs/de/cgi-bin/de.pl
>> +++ b/langs/de/cgi-bin/de.pl
>> @@ -835,6 +835,8 @@
>>   'dns error 0' => 'Die IP Adresse vom <strong>primären</strong> DNS Server ist nicht gültig, bitte überprüfen Sie Ihre Eingabe!<br />Die eingegebene <strong>sekundären</strong> DNS Server Adresse ist jedoch gültig.<br />',
>>   'dns error 01' => 'Die eingegebene IP Adresse des <strong>primären</strong> wie auch des <strong>sekundären</strong> DNS-Servers sind nicht gültig, bitte überprüfen Sie Ihre Eingaben!',
>>   'dns error 1' => 'Die IP Adresse vom <strong>sekundären</strong> DNS Server ist nicht gültig, bitte überprüfen Sie Ihre Eingabe!<br />Die eingegebene <strong>primäre</strong> DNS Server Adresse ist jedoch gültig.',
>> +'dns force on blue' => 'Erzwinge lokale DNS-Server',
>> +'dns force on green' => 'Erzwinge lokale DNS-Server',
>>   'dns forward disable dnssec' => 'DNSSEC deaktivieren (nicht empfohlen)',
>>   'dns forwarding dnssec disabled notice' => '(DNSSEC deaktiviert)',
>>   'dns header' => 'DNS Server Adressen zuweisen nur mit DHCP an red0',
>> @@ -1101,9 +1103,12 @@
>>   'from email server' => 'Von E-Mail-Server',
>>   'from email user' => 'Von E-Mail-Benutzer',
>>   'from warn email bad' => 'Von E-Mail-Adresse ist nicht gültig',
>> -'fw blue' => 'Firewalloptionen für das Blaue Interface',
>> +'fw blue' => 'Firewalloptionen für das <font color=\'#0000FF\'>BLAUE</font> Interface',
>>   'fw default drop' => 'Firewallrichtlinie',
>> +'fw green' => 'Firewalloptionen für das <font color=\'#339933\'>GRÜNE</font> Interface',
>>   'fw logging' => 'Firewallprotokollierung',
>> +'fw logging blue' => 'Firewallprotokollierung (<font color=\'#0000FF\'>BLAU</font>)',
>> +'fw logging red' => 'Firewallprotokollierung (<font color=\'#993333\'>ROT</font>)',
>>   'fw settings' => 'Firewalleinstellungen',
>>   'fw settings color' => 'Farben in Regeltabelle anzeigen',
>>   'fw settings dropdown' => 'Alle Netzwerke auf Regelerstellungsseite anzeigen',
>> @@ -1643,9 +1648,9 @@
>>   'map to guest' => 'Map to Guest',
>>   'march' => 'März',
>>   'marked' => 'Markiert',
>> -'masquerade blue' => 'NAT auf BLAU',
>> -'masquerade green' => 'NAT auf GRÜN',
>> -'masquerade orange' => 'NAT auf ORANGE',
>> +'masquerade blue' => 'NAT auf <b><font color=\'#0000FF\'>BLAU</font></b>',
>> +'masquerade green' => 'NAT auf <b><font color=\'#339933\'>GRÜN</font></b>',
>> +'masquerade orange' => 'NAT auf <b><font color =\'#FF9933\'>ORANGE</font></b>',
>>   'masquerading' => 'Masquerading/NAT',
>>   'masquerading disabled' => 'NAT ausgeschaltet',
>>   'masquerading enabled' => 'NAT eingeschaltet',
>> @@ -1813,6 +1818,8 @@
>>   'november' => 'November',
>>   'ntp common settings' => 'Allgemeine Einstellungen',
>>   'ntp configuration' => 'Zeitserverkonfiguration',
>> +'ntp force on blue' => 'Erzwinge lokale NTP-Server',
>> +'ntp force on green' => 'Erzwinge lokale NTP-Server',
>>   'ntp must be enabled to have clients' => 'Um Clients annehmen zu können, muss NTP vorher aktiviert sein.',
>>   'ntp server' => 'NTP-Server',
>>   'ntp sync' => 'Synchronisation',
>> diff --git a/langs/en/cgi-bin/en.pl b/langs/en/cgi-bin/en.pl
>> index 1c69b3798..390b2d026 100644
>> --- a/langs/en/cgi-bin/en.pl
>> +++ b/langs/en/cgi-bin/en.pl
>> @@ -858,6 +858,8 @@
>>   'dns error 0' => 'The IP address of the <strong>primary</strong> DNS server is not valid, please check your entries!<br />The entered <strong>secondary</strong> DNS server address is valid.',
>>   'dns error 01' => 'The entered IP address of the <strong>primary</strong> and <strong>secondary</strong> DNS server are not valid, please check your entries!',
>>   'dns error 1' => 'The IP address of the <strong>secondary</strong> DNS server is not valid, please check your entries!<br />The entered <strong>primary</strong> DNS server address is valid.',
>> +'dns force on blue' => 'Force DNS to use local DNS servers',
>> +'dns force on green' => 'Force DNS to use local DNS servers',
>>   'dns forward disable dnssec' => 'Disable DNSSEC (dangerous)',
>>   'dns forwarding dnssec disabled notice' => '(DNSSEC disabled)',
>>   'dns header' => 'Assign DNS server addresses only for DHCP on red0',
>> @@ -1128,9 +1130,12 @@
>>   'from email server' => 'From Email server',
>>   'from email user' => 'From e-mail user',
>>   'from warn email bad' => 'From e-mail address is not valid',
>> -'fw blue' => 'Firewall options for BLUE interface',
>> +'fw blue' => 'Firewall options for <font color=\'#0000FF\'>BLUE</font> Interface',
>>   'fw default drop' => 'Firewall policy',
>> +'fw green' => 'Firewall options for <font color=\'#339933\'>GREEN</font> Interface',
>>   'fw logging' => 'Firewall logging',
>> +'fw logging blue' => 'Firewall logging (<font color=\'#0000FF\'>BLUE</font>)',
>> +'fw logging red' => 'Firewall logging (<font color=\'#993333\'>RED</font>)',
>>   'fw settings' => 'Firewall settings',
>>   'fw settings color' => 'Show colors in ruletable',
>>   'fw settings dropdown' => 'Show all networks on rulecreation site',
>> @@ -1675,9 +1680,9 @@
>>   'map to guest' => 'Map to Guest',
>>   'march' => 'March',
>>   'marked' => 'Marked',
>> -'masquerade blue' => 'Masquerade BLUE',
>> -'masquerade green' => 'Masquerade GREEN',
>> -'masquerade orange' => 'Masquerade ORANGE',
>> +'masquerade blue' => 'Masquerade <b><font color=\'#0000FF\'>BLUE</font></b>',
>> +'masquerade green' => 'Masquerade <b><font color=\'#339933\'>GREEN</font></b>',
>> +'masquerade orange' => 'Masquerade <b><font color=\'#FF9933\'>ORANGE</font></b>',
>>   'masquerading' => 'Masquerading',
>>   'masquerading disabled' => 'Masquerading disabled',
>>   'masquerading enabled' => 'Masquerading enabled',
>> @@ -1847,6 +1852,8 @@
>>   'november' => 'November',
>>   'ntp common settings' => 'Common settings',
>>   'ntp configuration' => 'NTP Configuration',
>> +'ntp force on blue' => 'Force NTP to use local NTP servers',
>> +'ntp force on green' => 'Force NTP to use local NTP servers',
>>   'ntp must be enabled to have clients' => 'NTP must be enabled to have clients.',
>>   'ntp server' => 'NTP Server',
>>   'ntp sync' => 'Synchronization',
>> diff --git a/lfs/configroot b/lfs/configroot
>> index c528bd6d9..6cc376ff0 100644
>> --- a/lfs/configroot
>> +++ b/lfs/configroot
>> @@ -1,7 +1,7 @@
>>   ###############################################################################
>>   #                                                                             #
>>   # IPFire.org - A linux based firewall                                         #
>> -# Copyright (C) 2007-2021  IPFire Team  <info(a)ipfire.org>                     #
>> +# Copyright (C) 2007-2018  IPFire Team  <info(a)ipfire.org>                     #
>>   #                                                                             #
>>   # This program is free software: you can redistribute it and/or modify        #
>>   # it under the terms of the GNU General Public License as published by        #
>> @@ -129,6 +129,10 @@ $(TARGET) :
>>   	echo  "SHOWDROPDOWN=off"	>> $(CONFIG_ROOT)/optionsfw/settings
>>   	echo  "DROPWIRELESSINPUT=on"	>> $(CONFIG_ROOT)/optionsfw/settings
>>   	echo  "DROPWIRELESSFORWARD=on"	>> $(CONFIG_ROOT)/optionsfw/settings
>> +	echo  "DNS_FORCE_ON_GREEN=off"	>> $(CONFIG_ROOT)/optionsfw/settings
>> +	echo  "DNS_FORCE_ON_BLUE=off"	>> $(CONFIG_ROOT)/optionsfw/settings
>> +	echo  "NTP_FORCE_ON_GREEN=off"	>> $(CONFIG_ROOT)/optionsfw/settings
>> +	echo  "NTP_FORCE_ON_BLUE=off"	>> $(CONFIG_ROOT)/optionsfw/settings
>>   	echo  "POLICY=MODE2"		>> $(CONFIG_ROOT)/firewall/settings
>>   	echo  "POLICY1=MODE2"		>> $(CONFIG_ROOT)/firewall/settings
>>   	echo  "USE_ISP_NAMESERVERS=on"  >> $(CONFIG_ROOT)/dns/settings
>> diff --git a/src/initscripts/system/dnsntp b/src/initscripts/system/dnsntp
>> new file mode 100644
>> index 000000000..54fdfc685
>> --- /dev/null
>> +++ b/src/initscripts/system/dnsntp
>> @@ -0,0 +1,43 @@
>> +#!/bin/sh
>> +########################################################################
>> +# Begin $rc_base/init.d/dnsntp
>> +#
>> +# Description : dnsntp init script for DNS/NTP rules only
>> +#
>> +########################################################################
>> +
>> +# flush chain
>> +iptables -t nat -F DNS_NTP_REDIRECT
>> +
>> +eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings)
>> +eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings)
>> +
> 
> The 'well-behaving' request destinations should be DNS1_GREEN, 
> DNS2_GREEN, DNS1_BLUE, DNS2_BLUE ( stored in /var/ipfire/dhcp/settings 
> and set in the dhcp.cgi ).
> If they are defined and distrubited by DHCP or set by other mechanism.

Ok, here we are.
Ups!
"DNS1_..." and "DNS2_..." entries. What/where are these? You've got me!

But now I'm a bit puzzled. Perhaps I need some hints again.

Because until now I completely ignored DNS1_GREEN, DNS2_... etc. from
DHCP. They existed in my installation(s) - but DHCP didn't play a role
in my considerations. Never. I always used the local IPFire addresses
(GREEN/BLUE). Nothing else. The addresses for "GREEN_ADDRESS" (Ethernet
settings), "DNS1_GREEN" and "NTP1_GREEN" (dhcp settings) were always the
same. Of course, this also applied to BLUE.

BTW, what would be the sense of distributing different DNS1/DNS2 entries
through DHCP vs. the DOT entries under "domain name system" (e.g.)?

What I don't understand - call it "I'm thick at the moment...":
Through the current GUIs it would be possible to choose and distribute
(e.g.) 8.8.8.8 as "DNS1" or "DNS2" through DHCP, while the "Domain Name
System" page contains totally different (or ISP servers). Are there any
circumstances where this would be useful or needed? And which could
these be?

> Is GREEN_ADDRESS / BLUE_ADDRESS the desired destination otherwise?

Yes. That was my only intention in the first place.
I wanted to keep it simple.
I wanted to make sure that my clients only use the specific *local* DNS
servers running on GREEN / BLUE. And I didn't realize the possibility to
enter completely different servers (through DHCP).
That's why I ignored DHCP and chose the GREEN and BLUE interface
(ethernet) addresses. I never thought of writing other addresses than
the local IPFire GREEN/BLUE addresses in the first required DHCP fields
for GREEN / BLUE. My fault(?). Hm.

Regarding 'forcing dns':
You can of course always turn these OFF if they don't correspond with
your wanted installation and use other DNS1 / DNS2 entries. ;-)

Last question(s):
If I got you right it would make more sense or be better to change the
RETURN rules to use the DHCP values from "$DNS1/2_GREEN/BLUE"!?

And what would be the best way to integrate *both* possible DNS entries
in the initscript? Regarding DoT, are these two really needed anymore?
At the moment, I'm using nine through DoT...

First needed change in 'dnsntpctrl' => evaluate DHCP settings. Add:
...
eval $(/usr/local/bin/readhash /var/ipfire/dhcp/settings)
...

New:
iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -d ${DNS1_GREEN} -p
udp -m udp --dport domain -j RETURN

And then?

I must think this over...its been a long week... ;-)

Regards,
Matthias

>> +# Force DNS REDIRECTs on GREEN (udp, tcp, 53)
>> +if [ "$DNS_FORCE_ON_GREEN" == "on" ]; then
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -d ${GREEN_ADDRESS} -p udp -m udp --dport domain -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -p udp -m udp --dport domain -j REDIRECT
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -d ${GREEN_ADDRESS} -p tcp -m tcp --dport domain -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -p tcp -m tcp --dport domain -j REDIRECT
>> +fi
>> +
>> +# Force DNS REDIRECTs on BLUE (udp, tcp, 53)
>> +if [ "$DNS_FORCE_ON_BLUE" == "on" ]; then
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -d ${BLUE_ADDRESS} -p udp -m udp --dport domain -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -p udp -m udp --dport domain -j REDIRECT
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -d ${BLUE_ADDRESS} -p tcp -m tcp --dport domain -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -p tcp -m tcp --dport domain -j REDIRECT
>> +fi
>> +
> 
> See above.
> 
> Regards,
> Bernhard
> 
>> +# Force NTP REDIRECTs on GREEN (udp, 123)
>> +if [ "$NTP_FORCE_ON_GREEN" == "on" ]; then
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -d ${GREEN_ADDRESS} -p udp -m udp --dport ntp -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${GREEN_DEV} -p udp -m udp --dport ntp -j REDIRECT
>> +fi
>> +
>> +# Force DNS REDIRECTs on BLUE (udp, 123)
>> +if [ "$NTP_FORCE_ON_BLUE" == "on" ]; then
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -d ${BLUE_ADDRESS} -p udp -m udp --dport ntp -j RETURN
>> +	iptables -t nat -A DNS_NTP_REDIRECT -i ${BLUE_DEV} -p udp -m udp --dport ntp -j REDIRECT
>> +fi
>> +
>> +# End $rc_base/init.d/dnsntp
>> diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall
>> index 1e558ee86..047946a86 100644
>> --- a/src/initscripts/system/firewall
>> +++ b/src/initscripts/system/firewall
>> @@ -218,7 +218,7 @@ iptables_init() {
>>   	iptables -A INPUT -j LOCATIONBLOCK
>>   	iptables -A FORWARD -j LOCATIONBLOCK
>>   
>> -	# trafic from ipsecX/TUN/TAP interfaces, before "-i GREEN_DEV" accept everything
>> +	# traffic from ipsecX/TUN/TAP interfaces, before "-i GREEN_DEV" accept everything
>>   	iptables -N IPSECINPUT
>>   	iptables -N IPSECFORWARD
>>   	iptables -N IPSECOUTPUT
>> @@ -242,6 +242,10 @@ iptables_init() {
>>   	iptables -N WIRELESSFORWARD
>>   	iptables -A FORWARD -m conntrack --ctstate NEW -j WIRELESSFORWARD
>>   
>> +	# Redirecting DNS and NTP requests
>> +	iptables -t nat -N DNS_NTP_REDIRECT
>> +	iptables -t nat -A PREROUTING -j DNS_NTP_REDIRECT
>> +
>>   	# OpenVPN
>>   	iptables -N OVPNINPUT
>>   	iptables -A INPUT -j OVPNINPUT
>> @@ -320,6 +324,9 @@ iptables_init() {
>>   	# run captivectrl
>>   	/usr/local/bin/captivectrl
>>   
>> +	# run dnsntpctrl
>> +	/usr/local/bin/dnsntpctrl
>> +
>>   	# POLICY CHAIN
>>   	iptables -N POLICYIN
>>   	iptables -A INPUT -j POLICYIN
>> diff --git a/src/misc-progs/Makefile b/src/misc-progs/Makefile
>> index 7c3ef7529..229d122d6 100644
>> --- a/src/misc-progs/Makefile
>> +++ b/src/misc-progs/Makefile
>> @@ -30,7 +30,7 @@ SUID_PROGS = squidctrl sshctrl ipfirereboot \
>>   	wirelessctrl getipstat qosctrl \
>>   	redctrl syslogdctrl extrahdctrl sambactrl \
>>   	smartctrl clamavctrl addonctrl pakfire mpfirectrl wlanapctrl \
>> -	setaliases urlfilterctrl updxlratorctrl fireinfoctrl rebuildroutes \
>> +	setaliases urlfilterctrl updxlratorctrl fireinfoctrl rebuildroutes dnsntpctrl \
>>   	getconntracktable wirelessclient torctrl ddnsctrl unboundctrl \
>>   	captivectrl
>>   
>> diff --git a/src/misc-progs/dnsntpctrl.c b/src/misc-progs/dnsntpctrl.c
>> new file mode 100644
>> index 000000000..f2a3b89e3
>> --- /dev/null
>> +++ b/src/misc-progs/dnsntpctrl.c
>> @@ -0,0 +1,19 @@
>> +/* This file is part of the IPFire Firewall.
>> + *
>> + * This program is distributed under the terms of the GNU General Public
>> + * Licence.  See the file COPYING for details.
>> + *
>> + */
>> +
>> +#include <stdlib.h>
>> +#include "setuid.h"
>> +
>> +int main(void)
>> +{
>> +	if (!(initsetuid()))
>> +		exit(1);
>> +
>> +	safe_system("/etc/rc.d/init.d/dnsntp >/dev/null 2>&1");
>> +
>> +	return 0;
>> +}
>> 
>