5

So I'm trying to set up reverse DNS for an IPv6 address using BIND9, and I'm having a little trouble getting it to work.

Assume I have 2001:41D0:2:D447::/64 assigned to my server and I want 2001:41d0:2:d447:0:0:0:ddc0 to resolve to just.an.example.com

I have the following in named.conf.local

zone "example.com" {
    type master;
    file "/etc/bind/example.com";
};
zone "7.4.4.d.2.0.0.0.0.d.1.4.1.0.0.2.ip6.arpa" {
       type master;
       file "/etc/bind/2001:41d0:2:d447::.rdns";
};

In example.com I have the line 

just.an.example.com.   IN  AAAA    2001:41d0:2:d447:0:0:0:ddc0

which appears to work fine.

In 2001:41d0:2:d447::.rdns I have

$TTL 1h

@       IN      SOA     ns1.example.com.  admin.example.com. (
        2014103002      ; serial
        1h              ; slave refresh interval
        15m             ; slave retry interval
        1w              ; slave copy expire time
        1h              ; NXDOMAIN cache time
        )

@       IN      NS      ns1.example.com.

0.c.d.d.0.0.0.0.0.0.0.0.0.0.0.0    IN    PTR    just.an.example.com.

and this doesn't appear to work. I think I'm messing up one of the IPv6 addresses in either the PTR line or the zone line in named.conf.local.

Does anyone spot anything wrong syntax wise?

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1
  • LGTM. Must be a problem with the delegation or else not querying the right server? Commented Oct 30, 2014 at 22:32

1 Answer 1

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8

I test with a command like:

 host 2001:41d0:2:d447:0:0:0:ddc0 localhost

This looks good, but your default acl may prevent access. Try adding allow-query { any; }; to the zone definition. You may also want to enable zone transfers

If you enable zone transfers you can test with a command like:

 host -t axfr 2.2.b.0.1.1.f.1.0.7.4.0.1.0.0.2.ip6.arpa localhost

Try checking the zone file and configuration.

named-checkzone -i full 7.4.4.d.2.0.0.0.0.d.1.4.1.0.0.2.ip6.arpa /etc/bind/2001:41d0:2:d447::.rdns
named-checkconf -z

Reload bind and check the logs for errors. If you still have issues, try enabling logging. 

logging {
    channel security_file {
            file "/var/log/named/security.log" versions 10 size 10k;
            severity dynamic;
            print-time yes;
    };
    channel simple_log {
            file "/var/log/named/bind.log" versions 10 size 50k;
            severity warning;
            print-time yes;
            print-severity yes;
            print-category yes;
    };
    channel query_log {
            file "/var/log/named/query.log" versions 10 size 1m;
            severity info;
            print-time yes;
    };

};
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3
  • Hey, I've given your suggestions a try and I still can't manage to get it working. host 2001:41d0:2:d447:0:0:0:ddc0 localhost returns 0.c.d.d.0.0.0.0.0.0.0.0.0.0.0.0.7.4.4.d.2.0.0.0.0.d.1.4.1.0.0.2.ip6.arpa domain name pointer just.an.example.com. named-checkzone -i full 7.4.4.d.2.0.0.0.0.d.1.4.1.0.0.2.ip6.arpa /etc/bind/2001:41d0:2:d447::.rdns returns zone 7.4.4.d.2.0.0.0.0.d.1.4.1.0.0.2.ip6.arpa/IN: loaded serial 2014103002 No errors other than the occasional error (chase DS servers) resolving '185.in-addr.arpa/DS/IN': 8.8.8.8#53 host -t axfr returns all the record Commented Oct 31, 2014 at 21:26
  • @Shilgen The host lookup shows that the PTR lookup is working. That is the expected output. What do you think is not working? Commented Nov 4, 2014 at 1:43
  • I've actually found that it's an issue with my server host, so I guess I'll have to talk to them about it. Thanks for the help - I'm going to mark your answer as correct as it helped me confirm the configuration was okay. Cheers! Commented Nov 6, 2014 at 23:00

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