BIND filter-aaaa

AberDino

Yesterday, I upgraded pfSense to 2.4.5 (without issues I might add) and I updated all my packages, including BIND. The BIND version is now 9.14_2.

I am using BIND purely to filter out IPv6 addresses for certain domains (domain overrides set up on DNS resolver), because I'm using a HE IPv6 tunnel and certain services don't work across this tunnel, as reported elsewhere. I used the "filter-aaaa-on-v4 yes" option for this, in the BIND custom options box. This used to work well, but not any more.

From what I can tell, this functionality used to be implemented natively, but now needs a plugin "filter-aaaa.so". So, I removed the "filter-aaaa-on-v4 yes" custom option, and in the global settings box I added:

plugin query "/usr/local/lib/named/filter-aaaa.so" {
        filter-aaaa-on-v4 yes;
};

I have verified that the "filter-aaaa.so" file is in the correct location, and the entries appear properly in "named.conf". However, BIND is not liking it for some reason:

failed to dlopen() plugin '/usr/local/lib/named/filter-aaaa.so': Cannot open "/usr/local/lib/named/filter-aaaa.so"
/usr/local/lib/named/filter-aaaa.so: plugin configuration failed: failure

Any thoughts on how I could get this working again?

Thanks in advance.

bmeeks

Just a wild guess on my part, but maybe check file permissions. bind may well not be running as root, and thus the user bind is running under might need more permissions to load and execute that library.

Gertjan

@AberDino said in BIND filter-aaaa:

/usr/local/lib/named/filter-aaaa.so

I don't use bind myself - not for pfSense, that is, but have one question back : bind (named) isn't chrooted on some location ?

edit : @bmeeks is right :

-rw-r--r--   1 root  wheel  22822 Jan 13 19:29 filter-aaaa.so

The owner and group might need a "chown" ^^

johnpoz

So you running bind along with unbound? You can do filtering of AAAA just in unbound, no reason to run bind just for this feature.. This is from 3 years ago..

https://forum.netgate.com/topic/118566/netflix-and-he-net-tunnel-fixed-using-unbound-python-module

AberDino

@johnpoz said in BIND filter-aaaa:

So you running bind along with unbound? You can do filtering of AAAA just in unbound, no reason to run bind just for this feature.. This is from 3 years ago.

Correct, and happy to give AAAA filtering in unbound a go. I had a look at the article and it seems things have moved on even further in the sense that it is now possible to select "Enable Python Module" on the General Settings page for the DNS Resolver. I presume that takes care of the first step in the article, i.e. enabling the python module in unbound.conf?

I don't have any experience with python, and I'm getting stuck after that. After enabling the python module, two additional options appear; python module order (pre-validator or post-validator) and python module script. What should I select for the first option, and where do I put my "py" file so I can select it from the drop-down?

Thanks for your help!

johnpoz

Let me take a look see, haven't played with this much after that thread 3 years ago ;) hehehe

AberDino

@johnpoz said in BIND filter-aaaa:

Let me take a look see, haven't played with this much after that thread 3 years ago ;) hehehe

Thank you . Perhaps this link is of some use.

johnpoz

Are you on 2.4.5?

This works fine...

I copped the script to /var/unbound.. Unbound now sees it.

[2.4.5-RELEASE][admin@sg4860.local.lan]/var/unbound: dig AAAA netflix.com

; <<>> DiG 9.14.9 <<>> AAAA netflix.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23617
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;netflix.com.                   IN      AAAA

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Mar 28 07:53:07 CDT 2020
;; MSG SIZE  rcvd: 40

If I turn that off... Then netflix resolves

[2.4.5-RELEASE][admin@sg4860.local.lan]/var/unbound: dig AAAA netflix.com

; <<>> DiG 9.14.9 <<>> AAAA netflix.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19719
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;netflix.com.                   IN      AAAA

;; ANSWER SECTION:
netflix.com.            3600    IN      AAAA    2406:da00:ff00::6b17:de40
netflix.com.            3600    IN      AAAA    2406:da00:ff00::23a8:b7b1
netflix.com.            3600    IN      AAAA    2406:da00:ff00::34ce:7a8a
netflix.com.            3600    IN      AAAA    2406:da00:ff00::3657:bca9
netflix.com.            3600    IN      AAAA    2406:da00:ff00::36a4:fed8
netflix.com.            3600    IN      AAAA    2406:da00:ff00::3698:ef03
netflix.com.            3600    IN      AAAA    2406:da00:ff00::36a5:9d7b
netflix.com.            3600    IN      AAAA    2406:da00:ff00::3436:9ae2

;; Query time: 198 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Mar 28 07:55:58 CDT 2020
;; MSG SIZE  rcvd: 264

[2.4.5-RELEASE][admin@sg4860.local.lan]/var/unbound:

Grab that script that is linked too, put in a file called no-aaaa.py and copy that file to your /var/unbound dir

edit: btw - there are couple of ways to skin this cat if you don't care about just blocking this specific device from all IPv6 or nobody from resolving IPv6 for netflix... You can use simple private domain entry..

AberDino

@johnpoz said in BIND filter-aaaa:

I copped the script to /var/unbound.

That's the bit I was missing. All working beautifully now, thank you!

Gertjan

Same thing here : completely forgot about that one !
But, as I'm using tunnelbroker.he.net also, and need to block some - not only Netflix, IPv6 AAAA"s.
Example : when I visit my ISP main web site using AAAA, it's often just doesn't work well.

@johnpoz said in BIND filter-aaaa:

Grab that script that is linked too, put in a file called no-aaaa.py and copy that file to your /var/unbound dir

I still think it's needed to copy the python script over to the /var/unbound and /var/unbound/var/unbound - the lather has to be created on start, and has to have the right owner, unbound.

As of today - using 2.4.5 - it's still working :

Btw I'm using 'ln' to link copy to populate /var/unbound/var/unbound from the copy in /var/unbound

#!/bin/sh

# https://forum.pfsense.org/index.php?topic=134352.msg737158#msg737158
echo "Inserting netflix-no-aaaa.py ...."

#make sure the directory for the python libraries is in the chroot
mkdir -p /var/unbound/usr/local/lib/python2.7

#link the actual python library directory to the chroot's directory
mount -t nullfs /usr/local/lib/python2.7 /var/unbound/usr/local/lib/python2.7

#copy the python script to the /var/unbound directory so 
#unbound-checkconf can find it
rm -f /var/unbound/netflix-no-aaaa.py
cp /root/netflix-no-aaaa.py /var/unbound/netflix-no-aaaa.py

#make sure unbound can read it
chown unbound:unbound /var/unbound/netflix-no-aaaa.py

#create a /var/unbound directory in the /var/unbound directory so that 
#unbound can find the script
mkdir -p /var/unbound/var/unbound

#copy the python module into the /var/unbound/var/unbound directory under the chroot #directory
rm -f /var/unbound/var/unbound/netflix-no-aaaa.py
ln -s /var/unbound/netflix-no-aaaa.py /var/unbound/var/unbound/netflix-no-aaaa.py

echo "Done ...."

The thing is set up when pfSense starts using an earlyshellcmd command :

/root/unbound-p.sh is the script shown above.
It's placed in /root, together with the /root/netflix-no-aaaa.py script.

johnpoz

It was working without that..

Gertjan

Do you mean that putting in place the "netflix-no-aaaa.py" is enough ?

No more coping the script to /var/unbound/var/unbound/
and no more mounting of the /usr/local/lib/python2.7 dir ?

johnpoz

That is all I did - then you see it in the new 2.4.5 gui and bobs your uncle.

Gertjan

Ok, nice. That cleans up things.

Will include a "Note" with the source of that python file, to complete my "in case of total rebuild" procedure.

geekmug

@AberDino said in BIND filter-aaaa:

Any thoughts on how I could get this working again?

@Gertjan said in BIND filter-aaaa:

I don't use bind myself - not for pfSense, that is, but have one question back : bind (named) isn't chrooted on some location ?

I just upgraded and ran into this myself. Yes, pfSense uses /cf/named as the chroot. The issue is that /usr/local/lib/named is a new directory that holds the plugins that needs to get copied into /cf/named/usr/local/lib/named. I've pushed up a pull request to fix this:

https://github.com/pfsense/FreeBSD-ports/pull/816

Until the pull request gets merged and an updated package is published, you could patch the bind.inc locally, and then run /etc/rc.packages bind post-install to regenerate the chroot.

bruor

It would be fantastic if the filtering of AAAA could be added as a native script whose list of domains to filter could be edited in the interface. This works great but I worry about having to recreate this if I ever have to restore from a backup in a few years.

AndrewZ

@johnpoz said in BIND filter-aaaa:

Grab that script that is linked too, put in a file called no-aaaa.py and copy that file to your /var/unbound dir

Upgraded to 2.4.5_1 and noticed that this file [that was there for quite some time] - no-aaaa.py - is gone. Copied it over, rebooted and noticed that the file is gone again. Finally, realized that /var/ is mounted in RAM. So, where this file should be stored?

jimp

Would be safe in /root or /conf or a subdirectory of those.

johnpoz

Not sure what your taking about on 2.4.5p1 and file is right where it was in /var/unbound

2.4.5-RELEASE][admin@sg4860.local.lan]/root: cd /var/unbound
[2.4.5-RELEASE][admin@sg4860.local.lan]/var/unbound: ls -la
total 84
drwxr-xr-x   5 unbound  unbound  1024 Jun 16 05:37 .
drwxr-xr-x  31 root     wheel     512 Jun  2 16:54 ..
-rw-r--r--   1 root     unbound   185 Jun 14 07:14 access_lists.conf
drwxr-xr-x   2 unbound  unbound   512 Jun  2 16:54 conf.d
drwxr-xr-x   2 root     unbound   512 Mar 28 07:52 dev
-rw-r--r--   1 root     unbound   698 Jun 14 07:14 dhcpleases_entries.conf
-rw-r--r--   1 root     unbound    65 Jun 14 07:14 domainoverrides.conf
-rw-r--r--   1 root     unbound  6838 Jun 14 07:14 host_entries.conf
-rw-r--r--   1 root     unbound  1404 Mar 28 07:51 no-aaaa.py
-rw-r--r--   1 root     unbound     0 Jun 16 15:00 pfb_dnsbl.conf
-rw-r--r--   1 root     unbound   300 Sep 17  2017 remotecontrol.conf
-rw-r--r--   1 unbound  unbound   758 Jun 16 05:37 root.key
-rw-r--r--   1 unbound  unbound   759 Dec  4  2019 root.key.67289-2
-rw-r--r--   1 root     unbound  3369 Feb 28  2019 sslcert.crt
-rw-------   1 root     unbound     0 Feb 28  2019 sslcert.key
-rw-r--r--   1 root     unbound  5297 Jun 14 07:14 unbound.conf
-rw-r-----   1 unbound  unbound  2455 Sep 17  2017 unbound_control.key
-rw-r-----   1 unbound  unbound  1330 Sep 17  2017 unbound_control.pem
-rw-r-----   1 unbound  unbound  2459 Sep 17  2017 unbound_server.key
-rw-r-----   1 unbound  unbound  1318 Sep 17  2017 unbound_server.pem
drwxr-xr-x   3 root     unbound   512 Mar 28 07:52 usr
[2.4.5-RELEASE][admin@sg4860.local.lan]/var/unbound: cat no-aaaa.py 
def init(id, cfg):
    return True

def deinit(id):
    return True

def inform_super(id, qstate, superqstate, qdata):
    return True

domains = [
    "netflix.com.",
    "nflxso.net.",
]

def operate(id, event, qstate, qdata):
    if event == MODULE_EVENT_NEW or event == MODULE_EVENT_PASS:
        if qstate.qinfo.qtype != RR_TYPE_AAAA:
            qstate.ext_state[id] = MODULE_WAIT_MODULE
            return True

        for domain in domains:
            if qstate.qinfo.qname_str == domain or qstate.qinfo.qname_str.endswith("." + domain):
                msg = DNSMessage(qstate.qinfo.qname_str, RR_TYPE_A, RR_CLASS_IN, PKT_QR | PKT_RA | PKT_AA)
                if not msg.set_return_msg(qstate):
                    qstate.ext_state[id] = MODULE_ERROR
                    return True
                # We don't need validation, result is valid
                qstate.return_msg.rep.security = 2
                qstate.return_rcode = RCODE_NOERROR
                qstate.ext_state[id] = MODULE_FINISHED
                log_info("no-aaaa: blocking AAAA request for %s" % qstate.qinfo.qname_str)
                return True

        qstate.ext_state[id] = MODULE_WAIT_MODULE
        return True

    if event == MODULE_EVENT_MODDONE:
        qstate.ext_state[id] = MODULE_FINISHED
        return True

AndrewZ

I see something different on my system (apu2)...
Then I realized that I have Use memory file system for /tmp and /var set. Now all is clear. It looks like I never rebooted my router after the previous upgrade!