[ILUG] Strange rsync issues

[Brian O'Mahony]

Andrew

There is nothing in either hosts.allow or hosts.deny on either server. They are both using the same nameserver (in dublin). Here is a little more information for clarity.

The server in BLR is pulling data from the server in dublin. It is synching 8 different folders at about 1am Irish time. The first rsynch fails, and the further seven complete.I added the first rsynch to the crontab again about 8 mins later, and it DOES complete, even though the first one still fails. Also this has been running for at least four years without problems. I only picked up on the errors in the last few weeks, but when i checked the date on the rsynchs i was probably a day or two behind.

Hope that is more information to go on.

I will try your ideas later today.

B

________________________________________
From: Andrew McGill [list2009 at lunch.za.net]
Sent: 22 January 2010 21:30
To: ilug at linux.ie
Cc: Brian O'Mahony
Subject: Re: [ILUG] Strange rsync issues

---
> Anyone have any ideas?
I'll bet the receiving server is doing a tcpwrappers check.  I'll guess your
hosts.deny says to be unfriendly, and /etc/hosts.allow says:

        sshd: server.bangalore.in

When you connect from bangalore, tcpwrappers does the rough equivalent of:
     dig -x 88.88.88.88  (which hopefully says server.bangalore.in)
     dig server.bangalore.in (which hopefully says 88.88.88.88)

One of these DNS requests is probably failing.  When the DNS lookup is
retried, the cached results from the first previous query allow the lookup to
complete.  The problem may be with the DNS registration itself -- some of the
NS servers in the chain may fail to respond (squish.net has a nice checker).
You  may also have a poor or incorrect nameserver configured in resolv.conf.

You can use an IP address in hosts.allow, check your DNS server, create a
/etc/hosts entry :) or hack it by making a connection to almost any port that
will trigger a reverse DNS check.

>
> B
&:-)


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