Reproducable failure with rsync, iptables and RHEL4

Jason Haar Jason.Haar at
Sun Feb 18 08:23:08 GMT 2007

Timothy J. Massey wrote:
> Hello!
> I have a consistent, reproducable failure performing an rsync of an
> RHEL4 system running rsync in daemon mode with iptables enabled.  With
> iptables disabled, or with a rule that explicitly allows all traffic,
> the rsync completes.  However, with iptalbes enabled, the rsync
> starts, but will not finish.  It fails after copying a seemingly
> random amount of data.
Could it be you're hitting a iptables session timeout setting? e.g. if
(during a rsync transfer) rsync "hangs" while reading in a large
directory listing, iptables may decide that tcp session is  dead. Then
when tcp packets start flowing again, iptables sees them as part of a
new tcp session - and they're not part of an existing session - so
they're rejected.

ethereal/wireshark should be able to prove that. (however, I think all
the "hanging" rsync does is right back in the beginning - which doesn't
match your symptoms)


Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1

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