> On Dec 5, 2016, at 5:15 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > > "dennisr@xxxxxxxx" <dennisr@xxxxxxxx> writes: >> Thanks for the quick reply. Here’s some details on how we have things configured. >> We are using RHEL 7.3, the DNS names below have been changed to protect the innocent or not so innocent depending on your point of view. > >> If I do a nslookup on the database host against the following CNAME some-cname-host.example.com <http://some-cname-host.example.com/> I get: > >> $> nslookup some-cname-host.example.com <http://some-cname-host.example.com/> >> Server: 10.97.40.215 >> Address: 10.97.40.215#53 > >> some-cname-host.example.com canonical name = canonical-host-name.example.com. >> Name: canonical-host-name.example.com >> Address: 10.65.160.213 > >> When I do the reverse lookup on the IP address return above I get the following: > >> $> nslookup 10.65.160.213 >> Server: 10.97.40.215 >> Address: 10.97.40.215#53 > >> 213.160.65.10.in-addr.arpa name = canonical-host-name.example.com. > > Given that, what you would have to put in pg_hba.conf is > canonical-host-name.example.com (and that needs to forward-resolve to > 10.65.160.213, and possibly other addresses as well). This cross-check > is meant to prevent getting into a PG server by means of a faked > reverse-DNS entry. > > (If you're wondering why we don't simply accept anything that > some-cname-host.example.com forward-maps to, it's for performance reasons: > that would require resolving every DNS name in pg_hba.conf to see if it > matches, which could be pretty awful with long pg_hba.conf files.) > > regards, tom lane > OK thanks, sadly not the answer I was hoping for though. My preference is to use a network address for this stuff but I was over ruled and needed to use a host specific name or address in the config file. I wanted to use a CNAME in place of the A or PTR records so as in the event we ever have to rebuild a new WAL receiver, I would only need to repoint the CNAME in the DNS system and avoid the possibility of updating a few hundred pg_hba.conf’s with a new IP address or hostname (this is a private cloud environment I am working with so I don’t have a lot of control over hostnames of the nodes they give me or even the networks the node is placed in.) Dennis -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
