Cygwin unable to resolve hostnames

[Matthew Fountain]

I'm not sure when this started, but recently Cygwin has been unable to
resolve (certain) hostnames.

Example:
wget github.com
--2015-07-22 15:17:04-- http://github.com/
Resolving github.com (github.com)... failed: Non-recoverable failure
in name resolution.
wget: unable to resolve host address ‘github.com’

happens for SSH as well (I'm aware I probably can't ssh to github.com,
but it doesn't fail there, it fails during name resolution)
ssh github.com
ssh: Could not resolve hostname github.com: Non-recoverable failure in
name resolution

however, I can get to github.com in the browser sitting next to the
cygwin window just fine.
ping (from windows, but inside cygwin) also works...
ping github.com

Pinging github.com [192.30.252.129] with 32 bytes of data:
Reply from 192.30.252.129: bytes=32 time=43ms TTL=128

Interestingly enough, google.com DOES resolve correctly.
wget google.com
--2015-07-22 15:23:27-- http://google.com/
Resolving google.com (google.com)... 74.125.224.110, 74.125.224.99,
74.125.224.103, ...
Connecting to google.com (google.com)|74.125.224.110|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: http://www.google.com/ [following]
...........

No hostname other than google.com that I've tried resolves at all
unless it is defined in my Windows hosts file.

I've searched google, the mailing lists, and the faq in vain.

Any ideas?

Thanks!

--
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

[René Berber]

Post by Matthew Fountain
I'm not sure when this started, but recently Cygwin has been unable to
resolve (certain) hostnames.
wget github.com
--2015-07-22 15:17:04-- http://github.com/
Resolving github.com (github.com)... failed: Non-recoverable failure
in name resolution.

[snip]

Post by Matthew Fountain
Any ideas?

Cygwin by default uses the same resolution as Windows, that means that
you have something in Cygwin's configuration that affects resolution.

First and most obvious is /etc/resolv.conf; by default I don't think
there is one, but you can create it and Cygwin will use it.

Next would be if you have more than one DNS resolver in your (Windows)
network configuration, this means that any one of them can be used at
any time (literally it should be random)... and by coincidence Cygwin is
using one that doesn't work, the Web browser is using another, and
things change with different tests. Run 'ipconfig -all' and see under
the network adapter what's listed for "DNS Servers".

Also if there is more than one network adapter something similar to the
last paragraph will happen. I would think that Cygwin uses the DNS
servers on the "default" adapter.

Hope this helps.

[Carl-Erik Kopseng]

Post by René Berber

Post by Matthew Fountain
I'm not sure when this started, but recently Cygwin has been unable to
resolve (certain) hostnames.
wget github.com
--2015-07-22 15:17:04-- http://github.com/
Resolving github.com (github.com)... failed: Non-recoverable failure
in name resolution.

[snip]

I have the same problem and I have just made a clean Cygwin64 install
on a computer that has never had Cygwin installed before. I have not
messed with any settings, yet I also cannot use curl or git to access
almost any site. Only the built-in Windows CLI tools, such as `ping`,
works.

Post by René Berber

Post by Matthew Fountain
Any ideas?

Cygwin by default uses the same resolution as Windows, that means that
you have something in Cygwin's configuration that affects resolution.
First and most obvious is /etc/resolv.conf; by default I don't think
there is one, but you can create it and Cygwin will use it.

Pointers on what to actually put in that file?

Post by René Berber
Next would be if you have more than one DNS resolver in your (Windows)
network configuration, this means that any one of them can be used at
any time (literally it should be random)... and by coincidence Cygwin is
using one that doesn't work, the Web browser is using another, and
things change with different tests. Run 'ipconfig -all' and see under
the network adapter what's listed for "DNS Servers".
Also if there is more than one network adapter something similar to the
last paragraph will happen. I would think that Cygwin uses the DNS
servers on the "default" adapter.

I am guessing my problems have something to do with this part, as I am
running Windows 8.1 in VMWare. VMWare adds lots of weird network stuff,
all of which I am not too familiar with ...

The below output is from `ipconfig /all`. Could any of the info be put
in the aforementioned resolv.conf file?


Windows IP Configuration

Host Name . . . . . . . . . . . . : macbookpro
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : localdomain

Ethernet adapter Bluetooth Network Connection 2:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Bluetooth Device (Personal Area
Network) #2
Physical Address. . . . . . . . . : 00-50-56-E2-FB-E9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Ethernet0:

Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Intel(R) 82574L Gigabit Network
Connection
Physical Address. . . . . . . . . : 00-0C-29-6A-39-52
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::20b9:f45e:9310:3f4a%9(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.244.145(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, December 11, 2015 10:59:56
Lease Expires . . . . . . . . . . : Friday, December 11, 2015 11:29:56
Default Gateway . . . . . . . . . : 192.168.244.2
DHCP Server . . . . . . . . . . . : 192.168.244.254
DHCPv6 IAID . . . . . . . . . . . : 167775273
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
DNS Servers . . . . . . . . . . . : 192.168.244.2
Primary WINS Server . . . . . . . : 192.168.244.2
NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter Teredo Tunneling Pseudo-Interface:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . :
2001:0:5ef5:79fb:867:2876:3f57:b6e(Preferred)
Link-local IPv6 Address . . . . . : fe80::867:2876:3f57:b6e%7(Preferred)
Default Gateway . . . . . . . . . : ::
DHCPv6 IAID . . . . . . . . . . . : 218103808
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
NetBIOS over Tcpip. . . . . . . . : Disabled

Tunnel adapter isatap.localdomain:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes


Regards
Carl-Erik Kopseng

--
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

[Jan Bruun Andersen]

The only thing in that list of interfaces that have IP is the
"Ethernet adapter Ethernet0". Right of my head I don't see anything
obviously wrong. My first suggestion would be to disable IPv6 on the
adapter, just on the odd chance that it is the cause.

After that I would start ping'ing the default gateway by IP-address
(192.168.244.2). This also happens to be where your DNS lives, so that
will test 2 issues in one go.

Jan Bruun Andersen

Post by René Berber

Post by René Berber

Post by Matthew Fountain
I'm not sure when this started, but recently Cygwin has been unable to
resolve (certain) hostnames.
wget github.com
--2015-07-22 15:17:04-- http://github.com/
Resolving github.com (github.com)... failed: Non-recoverable failure
in name resolution.

[snip]
I have the same problem and I have just made a clean Cygwin64 install
on a computer that has never had Cygwin installed before. I have not
messed with any settings, yet I also cannot use curl or git to access
almost any site. Only the built-in Windows CLI tools, such as `ping`,
works.

Post by René Berber

Post by Matthew Fountain
Any ideas?

Cygwin by default uses the same resolution as Windows, that means that
you have something in Cygwin's configuration that affects resolution.
First and most obvious is /etc/resolv.conf; by default I don't think
there is one, but you can create it and Cygwin will use it.

Pointers on what to actually put in that file?

Post by René Berber
Next would be if you have more than one DNS resolver in your (Windows)
network configuration, this means that any one of them can be used at
any time (literally it should be random)... and by coincidence Cygwin is
using one that doesn't work, the Web browser is using another, and
things change with different tests. Run 'ipconfig -all' and see under
the network adapter what's listed for "DNS Servers".
Also if there is more than one network adapter something similar to the
last paragraph will happen. I would think that Cygwin uses the DNS
servers on the "default" adapter.

I am guessing my problems have something to do with this part, as I am
running Windows 8.1 in VMWare. VMWare adds lots of weird network stuff,
all of which I am not too familiar with ...
The below output is from `ipconfig /all`. Could any of the info be put
in the aforementioned resolv.conf file?
Windows IP Configuration
Host Name . . . . . . . . . . . . : macbookpro
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : localdomain
Media State . . . . . . . . . . . : Media disconnected
Description . . . . . . . . . . . : Bluetooth Device (Personal Area
Network) #2
Physical Address. . . . . . . . . : 00-50-56-E2-FB-E9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Intel(R) 82574L Gigabit Network
Connection
Physical Address. . . . . . . . . : 00-0C-29-6A-39-52
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::20b9:f45e:9310:3f4a%9(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.244.145(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, December 11, 2015 10:59:56
Lease Expires . . . . . . . . . . : Friday, December 11, 2015 11:29:56
Default Gateway . . . . . . . . . : 192.168.244.2
DHCP Server . . . . . . . . . . . : 192.168.244.254
DHCPv6 IAID . . . . . . . . . . . : 167775273
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
DNS Servers . . . . . . . . . . . : 192.168.244.2
Primary WINS Server . . . . . . . : 192.168.244.2
NetBIOS over Tcpip. . . . . . . . : Enabled
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
2001:0:5ef5:79fb:867:2876:3f57:b6e(Preferred)
Link-local IPv6 Address . . . . . : fe80::867:2876:3f57:b6e%7(Preferred)
DHCPv6 IAID . . . . . . . . . . . : 218103808
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
NetBIOS over Tcpip. . . . . . . . : Disabled
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Regards
Carl-Erik Kopseng
--
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

--
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

[Carl-Erik Kopseng]

I disabled IPv6. No change.
I pinged my gateway. Went fine, but still ssh fails.
I tried creating a /etc/resolv.conf with the same contents as the one
on my mac. Same difference.

And of course I have tried rebooting my VM. No change.

I still get

ssh: Could not resolve hostname timbuktu.kopseng.no: Non-recoverable
failure in name resolution


Just using the ip to connect using ssh works fine.

But an interesting tidbit of information is that it depends on the
domain name. While timbuktu.kopseng.no and most other domains fails,
trying to ssh into login.uio.no works! So name resolution definitively
seems related.


Regards
Carl-Erik Kopseng

Post by Jan Bruun Andersen
The only thing in that list of interfaces that have IP is the
"Ethernet adapter Ethernet0". Right of my head I don't see anything
obviously wrong. My first suggestion would be to disable IPv6 on the
adapter, just on the odd chance that it is the cause.
After that I would start ping'ing the default gateway by IP-address
(192.168.244.2). This also happens to be where your DNS lives, so that
will test 2 issues in one go.
Jan Bruun Andersen

Post by René Berber

Post by René Berber

Post by Matthew Fountain
I'm not sure when this started, but recently Cygwin has been unable to
resolve (certain) hostnames.
wget github.com
--2015-07-22 15:17:04-- http://github.com/
Resolving github.com (github.com)... failed: Non-recoverable failure
in name resolution.

[snip]
I have the same problem and I have just made a clean Cygwin64 install
on a computer that has never had Cygwin installed before. I have not
messed with any settings, yet I also cannot use curl or git to access
almost any site. Only the built-in Windows CLI tools, such as `ping`,
works.

Post by René Berber

Post by Matthew Fountain
Any ideas?

Cygwin by default uses the same resolution as Windows, that means that
you have something in Cygwin's configuration that affects resolution.
First and most obvious is /etc/resolv.conf; by default I don't think
there is one, but you can create it and Cygwin will use it.

Pointers on what to actually put in that file?

Post by René Berber
Next would be if you have more than one DNS resolver in your (Windows)
network configuration, this means that any one of them can be used at
any time (literally it should be random)... and by coincidence Cygwin is
using one that doesn't work, the Web browser is using another, and
things change with different tests. Run 'ipconfig -all' and see under
the network adapter what's listed for "DNS Servers".
Also if there is more than one network adapter something similar to the
last paragraph will happen. I would think that Cygwin uses the DNS
servers on the "default" adapter.

I am guessing my problems have something to do with this part, as I am
running Windows 8.1 in VMWare. VMWare adds lots of weird network stuff,
all of which I am not too familiar with ...
The below output is from `ipconfig /all`. Could any of the info be put
in the aforementioned resolv.conf file?
Windows IP Configuration
Host Name . . . . . . . . . . . . : macbookpro
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : localdomain
Media State . . . . . . . . . . . : Media disconnected
Description . . . . . . . . . . . : Bluetooth Device (Personal Area
Network) #2
Physical Address. . . . . . . . . : 00-50-56-E2-FB-E9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Intel(R) 82574L Gigabit Network
Connection
Physical Address. . . . . . . . . : 00-0C-29-6A-39-52
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::20b9:f45e:9310:3f4a%9(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.244.145(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, December 11, 2015 10:59:56
Lease Expires . . . . . . . . . . : Friday, December 11, 2015 11:29:56
Default Gateway . . . . . . . . . : 192.168.244.2
DHCP Server . . . . . . . . . . . : 192.168.244.254
DHCPv6 IAID . . . . . . . . . . . : 167775273
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
DNS Servers . . . . . . . . . . . : 192.168.244.2
Primary WINS Server . . . . . . . : 192.168.244.2
NetBIOS over Tcpip. . . . . . . . : Enabled
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
2001:0:5ef5:79fb:867:2876:3f57:b6e(Preferred)
Link-local IPv6 Address . . . . . : fe80::867:2876:3f57:b6e%7(Preferred)
DHCPv6 IAID . . . . . . . . . . . : 218103808
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-89-39-FB-14-10-9F-E1-7B-95
NetBIOS over Tcpip. . . . . . . . : Disabled
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : localdomain
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Regards
Carl-Erik Kopseng
--
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

--
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

--
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

[Corinna Vinschen]

Post by Carl-Erik Kopseng
I disabled IPv6. No change.
I pinged my gateway. Went fine, but still ssh fails.
I tried creating a /etc/resolv.conf with the same contents as the one
on my mac. Same difference.
And of course I have tried rebooting my VM. No change.
I still get
ssh: Could not resolve hostname timbuktu.kopseng.no: Non-recoverable
failure in name resolution

I don't think this is a generic Cygwin problem. I can resolve the
hostname just fine:

$ uname -svr
CYGWIN_NT-10.0 2.4.1(0.293/5/3) 2016-01-24 11:26
$ ssh timbuktu.kopseng.no
The authenticity of host 'timbuktu.kopseng.no (51.175.197.68)' can't be established.
RSA key fingerprint is SHA256:ddcghrb6BI6+TVDKDE3Yf+U43v9EL6u7HsNw7Hec+y8.
Are you sure you want to continue connecting (yes/no)? no
Host key verification failed.


Corinna

[Carl-Erik Kopseng]

I don't think it's a "generic Cygwin problem" either. If it was, the
mailing list would be flooded with people having problems with every
net based utility in existence :-)

I think it has to do with how Cygwin interfaces with VMs. Perhaps it
has something to do with network tunnelling or something related to
how ip and DNS works when being NAT'ed through VMWare Fusion.

I am running the Windows 8 VM on VMWare Fusion on OS X 10.11.3


Carl-Erik Kopseng
about.me/kopseng

Post by Corinna Vinschen

Post by Carl-Erik Kopseng
I disabled IPv6. No change.
I pinged my gateway. Went fine, but still ssh fails.
I tried creating a /etc/resolv.conf with the same contents as the one
on my mac. Same difference.
And of course I have tried rebooting my VM. No change.
I still get
ssh: Could not resolve hostname timbuktu.kopseng.no: Non-recoverable
failure in name resolution

I don't think this is a generic Cygwin problem. I can resolve the
$ uname -svr
CYGWIN_NT-10.0 2.4.1(0.293/5/3) 2016-01-24 11:26
$ ssh timbuktu.kopseng.no
The authenticity of host 'timbuktu.kopseng.no (51.175.197.68)' can't be established.
RSA key fingerprint is SHA256:ddcghrb6BI6+TVDKDE3Yf+U43v9EL6u7HsNw7Hec+y8.
Are you sure you want to continue connecting (yes/no)? no
Host key verification failed.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat

--
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

[Brian Inglis]

Post by Carl-Erik Kopseng

Post by Corinna Vinschen

Post by Carl-Erik Kopseng
ssh: Could not resolve hostname timbuktu.kopseng.no: Non-recoverable
failure in name resolution

I don't think this is a generic Cygwin problem. I can resolve the
$ uname -svr
CYGWIN_NT-10.0 2.4.1(0.293/5/3) 2016-01-24 11:26
$ ssh timbuktu.kopseng.no
The authenticity of host 'timbuktu.kopseng.no (51.175.197.68)' can't be established.
RSA key fingerprint is SHA256:ddcghrb6BI6+TVDKDE3Yf+U43v9EL6u7HsNw7Hec+y8.
Are you sure you want to continue connecting (yes/no)? no
Host key verification failed.

I think it has to do with how Cygwin interfaces with VMs. Perhaps it
has something to do with network tunnelling or something related to
how ip and DNS works when being NAT'ed through VMWare Fusion.
I am running the Windows 8 VM on VMWare Fusion on OS X 10.11.3

Could it be lack of support for DNSSEC as your domain shows:

$ whois kopseng.no
% Kopibeskyttet, se http://www.norid.no/domenenavnbaser/whois/kopirett.html
% Rights restricted by copyright. See
http://www.norid.no/domenenavnbaser/whois/kopirett.en.html

Domain Information

NORID Handle...............: KOP444D-NORID
Domain Name................: kopseng.no
Domain Holder Handle.......: CK1990P-NORID
Registrar Handle...........: REG42-NORID
Tech-c Handle..............: DH38R-NORID
Name Server Handle.........: NSHY11H-NORID
Name Server Handle.........: NSHY46H-NORID
Name Server Handle.........: NSHY81H-NORID
DNSSEC.....................: Signed
DS Key Tag 1...........: 42355
Algorithm 1...........: 8
Digest Type 1...........: 2
Digest 1...........:
8065b555e0009918e7aba49191e6409481afc702f028c0ff20f1bf27e847e21b

http://dnssec-debugger.verisignlabs.com/timbuktu.kopseng.no shows no issues
with setup.

VMware KB search shows no DNSSEC hits on Fusion, bunch on ESX.
Might want to start with
https://communities.vmware.com/message/1454999#1454999 and the rest of that
thread.
You can browse from there to more generic natd, dhcpd, and net config and
diag info or RTFM.



--
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

[Carl-Erik Kopseng]

Just a follow up for anyone else experiencing this. I fixed the DNS
issues by directly specifying a DNS server in the IPV4 settings for my
network adapter in the Windows VM. I used Google's public DNS server
(8.8.8.8) and it worked instantly.

The cue to check out DNSSEC was a dead-end as the hostname was just an
example. 90% of lookups failed, and the state of the net isn't that
bad :-)

--
regards

Carl-Erik Kopseng

--
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

[Jun-ya Kato]

It also depends on AAAA query againt VMware's DNS proxy server.

For more analysis, see vmware community site, https://communities.vmware.com/thread/518949?start=15&tstart=0


I think it is not cygwin's bug at all. but any workaround may be implemented againt weak behavior of GetAddrInfoW() API.






From: Carl-Erik Kopseng <***@gmail.com>
Subject: Re: Cygwin unable to resolve hostnames
Date: Sun, 13 Mar 2016 23:07:36 +0100

Post by Carl-Erik Kopseng
Just a follow up for anyone else experiencing this. I fixed the DNS
issues by directly specifying a DNS server in the IPV4 settings for my
network adapter in the Windows VM. I used Google's public DNS server
(8.8.8.8) and it worked instantly.
The cue to check out DNSSEC was a dead-end as the hostname was just an
example. 90% of lookups failed, and the state of the net isn't that
bad :-)
--
regards
Carl-Erik Kopseng
--
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

--
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

[Corinna Vinschen]

Post by Jun-ya Kato
It also depends on AAAA query againt VMware's DNS proxy server.
For more analysis, see vmware community site,
https://communities.vmware.com/thread/518949?start=15&tstart=0
I think it is not cygwin's bug at all. but any workaround may be
implemented againt weak behavior of GetAddrInfoW() API.

As mentioned in the above posting, Cygwin always sets AI_ALL if
ai_family is PF_UNSPEC and the hints don't specify AI_ADDRCONFIG.

Apparently Winsock's GetAddrInfoW chokes on AI_ALL in certain
circumstances. On GLibc, AI_ALL is ignored if AI_V4MAPPED is not given,
but that's not as I observed it on Windows when I added this code
(back in Vista times, but hey).

There's an easy workaround possible: If GetAddrInfoW returns the
error code WSANO_RECOVERY (per the above posting), we can retry
without the AI_ALL flag.

Is anybody here affected by this problem willing to give this a test?
I can create another Cygwin 2.5.0 test release pretty soon...


Thanks,
Corinna

[Jun-ya Kato]

Post by Corinna Vinschen
Is anybody here affected by this problem willing to give this a test?
I can create another Cygwin 2.5.0 test release pretty soon...

I think it's useful workaround for cygwin user under VMware NAT.
I'd like to test it.






From: Corinna Vinschen <corinna-***@cygwin.com>
Subject: Re: Cygwin unable to resolve hostnames
Date: Mon, 14 Mar 2016 10:54:59 +0100

Post by Corinna Vinschen

Post by Jun-ya Kato
It also depends on AAAA query againt VMware's DNS proxy server.
For more analysis, see vmware community site,
https://communities.vmware.com/thread/518949?start=15&tstart=0
I think it is not cygwin's bug at all. but any workaround may be
implemented againt weak behavior of GetAddrInfoW() API.

As mentioned in the above posting, Cygwin always sets AI_ALL if
ai_family is PF_UNSPEC and the hints don't specify AI_ADDRCONFIG.
Apparently Winsock's GetAddrInfoW chokes on AI_ALL in certain
circumstances. On GLibc, AI_ALL is ignored if AI_V4MAPPED is not given,
but that's not as I observed it on Windows when I added this code
(back in Vista times, but hey).
There's an easy workaround possible: If GetAddrInfoW returns the
error code WSANO_RECOVERY (per the above posting), we can retry
without the AI_ALL flag.
Is anybody here affected by this problem willing to give this a test?
I can create another Cygwin 2.5.0 test release pretty soon...
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat

--
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

[Corinna Vinschen]

Post by Jun-ya Kato

Post by Corinna Vinschen
Is anybody here affected by this problem willing to give this a test?
I can create another Cygwin 2.5.0 test release pretty soon...

I think it's useful workaround for cygwin user under VMware NAT.
I'd like to test it.

Thank you! I just uploaded 2.5.0-0.7 with the proposed patch.
It should be available on the mirrors shortly.


Thanks,
Corinna

[Jun-ya Kato]

Post by Corinna Vinschen
Thank you! I just uploaded 2.5.0-0.7 with the proposed patch.
It should be available on the mirrors shortly.

I fetched version 2.5.0-0.7.

ipv6 enabled command like a git or wget works fine under VMware NAT.

I also configured network adaptor to point to Google public cache
DNS directly. It seems there is no side effect on these commands.



--
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

[Corinna Vinschen]

Post by Jun-ya Kato

Post by Corinna Vinschen
Thank you! I just uploaded 2.5.0-0.7 with the proposed patch.
It should be available on the mirrors shortly.

I fetched version 2.5.0-0.7.
ipv6 enabled command like a git or wget works fine under VMware NAT.
I also configured network adaptor to point to Google public cache
DNS directly. It seems there is no side effect on these commands.

Cool. Thanks a lot for testing!


Corinna