Re: PostgreSQL and IPV6

On Sat, Nov 03, 2012 at 09:11:51AM +0100, Yvon Thoraval wrote:
> I'm using to computers :
> - a laptop under Xubuntu 12.04 with PostgreSQL 9.1
> - a desktop under Mac OS X Mountain Lion with PostgreSQL 9.2
> 
> After the switch to Mountain Lion, i had a small prob connecting to a
> database on my laptop.



> However when connecting from desktop to laptop, altough the IPV6 address of
> my desktop is in my pg_hba.conf,psql rejected the connection because an
> address terminating by "18cf" isn't in my pg_hba.conf.
> 
> Then i did verify my mac os x setup showing that this address is a valid
> one for my desktop, in fact my desktop does have up to eight IPV6 addresses.

IIRC MacOS X uses the IPv6 privacy extensions which means that clients
will regularly get different source IPs. The machine does this by
adding a new address every now and then.

A side effect of this is that you can't firewall on specific IP. A few
things I can think of:

- Find a way to fix the IP address.

- Use the link-local address (beginning with fe80) as they won't
  change. Only works on a single network ofcourse.

- Allow the whole subnet, rather than individual IPs.

> Why, in one direction from laptop to desktop i use successfully :
> 
> psql -h IPV6-terminating-by-2559
> 
> and the other way, from desktop to laptop this is IPV6-terminating-by-18cf
> being seen by the laptop's PostgreSQL ?

Linux does not use privacy extensions by default, so the IP address
doesn't change. Maybe that explains it?

Have a nice day,
-- 
Martijn van Oosterhout      http://svana.org/kleptog/
> He who writes carelessly confesses thereby at the very outset that he does
> not attach much importance to his own thoughts.
   -- Arthur Schopenhauer