On 6/7/2019 7:20 AM, Måns Nilsson wrote:
> Hi, 
> 
> I'm a little uncertain how to discuss this, because it is a
> cross-implementation problem, but this problem surely has hit others
> here. I hope.
> 
> I have three db servers in my OpenAFS cell. They all have -- for various
> reasons -- v4 and v6 addresses and corresponding DNS records. When I'm
> trying to use the Auristor-supplied OSX client "aklog" implementation to
> get tokens, the client tries to connect to the IPv6 addresses of the db
> servers. Most likely because it is an Auristor client and it is expecting
> Auristor db servers. Only after some 10 seconds does the client timeout
> and retry over v4, which of course immediately succeeds.
> 
> Is there a fix for this? 
> 
> Or: Am I the only one crazy enough to have AAAA records for my db servers? 

The AuriStorFS aklog relies upon DNS SRV records to find the list of
service endpoints for the protection servers.  If the DNS SRV record
refers to a name with a AAAA record, that entry will be trusted as valid.

Create separate IPv4 A records to refer to your hosts and list those in
the DNS SRV records instead of the hostname that includes both A and
AAAA records.  Note that SRV records reference A and AAAA records and
not CNAME records.  Many sites have

  afsdb1.cell
  afsdb2.cell
  afsdb3.cell

names in DNS.  Only create A records for those names and use them for
the DNS SRV records

  _afs3-vlserver._udp.cell
  _afs3-prserver._udp.cell
  ...

You wouldn't create SRV records indicating that your cell supports TCP
connections

  _afs3-vlserver._tcp.cell
  _afs3-prserver._tcp.cell

so do not create SRV records that indicate that the service supports
IPv6 when it doesn't.

The AuriStorFS rx stack will terminate calls within one second if an
ICMP6 port unreachable response is received.  I wonder if the 10 second
delay is due to ICMP6 packets being firewalled.

Jeffrey Altman

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