After running strace I was able to determine there was a problem calling cygwin_gethostname.
This led me to a recent thread "1.7.29-2: Exception from cygwin_gethostname". Replacing cygwin1.dll with the snapshot build referenced in that thread fixed my problem also. -----Original Message----- From: Peter Hancox Sent: Sunday, 20 April 2014 16:52 Subject: ssh: Could not resolve hostname xxx: Bad address OpenSSH under Cygwin just started failing with "Could not resolve host address". Originally this was actually using scp to transfer a file to a local host, however, the attached example is a simplified test case. Output from cygcheck attached. PS D:\WorkArea\Cygwin> ssh -vvvv www.ibm.com OpenSSH_6.6, OpenSSL 1.0.1g 7 Apr 2014 ssh: Could not resolve hostname www.ibm.com: Bad address PS D:\WorkArea\Cygwin> ping www.ibm.com Pinging e3062.x.akamaiedge.net [23.37.133.247] with 32 bytes of data: Reply from 23.37.133.247: bytes=32 time=19ms TTL=59 Reply from 23.37.133.247: bytes=32 time=19ms TTL=59 Reply from 23.37.133.247: bytes=32 time=19ms TTL=59 Reply from 23.37.133.247: bytes=32 time=20ms TTL=59 Ping statistics for 23.37.133.247: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 19ms, Maximum = 20ms, Average = 19ms Although this particular test was run from within Powershell, same results from command shell and bash. I am aware of the recent issue with mixed case host names but shouldn't be relevant in this case and OpenSSH and all installed Cygwin software is at latest versions. Have reinstalled OpenSSH just to be sure and still fails. Note that I have exactly the same Cygwin (x64) installed on a Windows Server 2012 instance running on Amazon EC2 and it continues to work fine. Not sure when this broke but I probably haven't attempted to use ssh from this machine for a couple of months. One thing that has definitely changed since the last use (and is different to the working instance) is installation of Windows 8.1 Update 1 patch. Running with "-vvvv" doesn't give any additional information other than version numbers. Nothing in Windows event logs. Suggestion for debugging further? REGARDS Peter ============================================================ DELTA Technology Consulting Telephone: +61(2)9420-1800 PO Box 1383 Lane Cove Facsimile: +61(2)9420-1899 NSW 1595 Australia WWW: http://www.dtc.com.au -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple