[lug] can ping the host, but can't ssh for a few seconds

[David Ahern]

Seems like ssh is telling you as much as it can:

"ssh: connect to host warsaw port 22: No route to host"

That suggest a failure on connect() with errno EHOSTUNREACH. If it is on 
the same LAN, then wouldn't that be an ARP lookup failure?

Does 'arp -n' show an entry for warsaw? Do all hosts agree on the netmask?


On 7/10/12 10:05 AM, Vishal Verma wrote:
> Hi,
>
> I was about to suggest the same. Try -vvv for lots of debug, but it
> will surely tell you at which point it fails.
> You can also look at the server side log, in something like /var/log/auth.log
>
> --
> Vishal
>
>
> On Tue, Jul 10, 2012 at 10:01 AM, Stephen Queen <svqueen at gmail.com> wrote:
>> Maybe try the -v option of ssh on the first iteration, see if it gives
>> you a hint why it is failing.
>> [software at saratoga build-jaws-svn]$ date; ping -c 1 warsaw;
>> /sbin/route; ssh -v software at warsaw
>>
>> Steve
>>
>> On 7/10/12, Michael Hirsch <mdhirsch at gmail.com> wrote:
>>> On Mon, Jul 9, 2012 at 1:29 PM, Ebben Aries <earies at dscp.org> wrote:
>>>
>>>> You are sending an echo req -> saratoga (localhost eth0 by the looks of
>>>> it), yet following that w/ a connection attempt to warsaw - have a look
>>>> at
>>>> your arp cache for warsaw's address if it is on the same segment or your
>>>> gw (192.168.1.1) if not.  Alter your ping statement to target warsaw
>>>> rather
>>>> to trigger an arp request prior to connection attempt. (which looks like
>>>> what you were attempting to do in the first place)
>>>>
>>>
>>> OMG, duh!  Don't know how I did that.  Obviously I should be pinging
>>> warsaw.  Thanks for pointing it out.
>>>
>>> Unfortunately, it still behaves like that.  Here is the output of pinging
>>> warsaw, then trying to ssh there.  Then I wait a short time and try again.
>>> The second time it connects.  The route hasn't changed.
>>>
>>> [software at saratoga build-jaws-svn]$ date; ping -c 1 warsaw; /sbin/route;
>>> ssh software at warsaw
>>> Tue Jul 10 09:15:12 MDT 2012
>>> PING warsaw.stirlingsystems.net (192.168.1.21) 56(84) bytes of data.
>>> 64 bytes from warsaw.stirlingsystems.net (192.168.1.21): icmp_seq=0 ttl=64
>>> time=4.54 ms
>>>
>>> --- warsaw.stirlingsystems.net ping statistics ---
>>> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
>>> rtt min/avg/max/mdev = 4.546/4.546/4.546/0.000 ms, pipe 2
>>> Kernel IP routing table
>>> Destination     Gateway         Genmask         Flags Metric Ref    Use
>>> Iface
>>> 172.16.30.0     *               255.255.255.0   U     0      0        0
>>> vmnet8
>>> 192.168.137.0   *               255.255.255.0   U     0      0        0
>>> vmnet1
>>> 192.168.8.0     192.168.1.51    255.255.255.0   UG    0      0        0
>>> eth0
>>> 192.168.0.0     *               255.255.252.0   U     0      0        0
>>> eth0
>>> 169.254.0.0     *               255.255.0.0     U     0      0        0
>>> eth0
>>> default         192.168.1.1     0.0.0.0         UG    0      0        0
>>> eth0
>>> ssh: connect to host warsaw port 22: No route to host
>>> [software at saratoga build-jaws-svn]$ date; ping -c 1 warsaw; /sbin/route;
>>> ssh software at warsaw
>>> Tue Jul 10 09:15:17 MDT 2012
>>> PING warsaw.stirlingsystems.net (192.168.1.21) 56(84) bytes of data.
>>> 64 bytes from warsaw.stirlingsystems.net (192.168.1.21): icmp_seq=0 ttl=64
>>> time=0.196 ms
>>>
>>> --- warsaw.stirlingsystems.net ping statistics ---
>>> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
>>> rtt min/avg/max/mdev = 0.196/0.196/0.196/0.000 ms, pipe 2
>>> Kernel IP routing table
>>> Destination     Gateway         Genmask         Flags Metric Ref    Use
>>> Iface
>>> 172.16.30.0     *               255.255.255.0   U     0      0        0
>>> vmnet8
>>> 192.168.137.0   *               255.255.255.0   U     0      0        0
>>> vmnet1
>>> 192.168.8.0     192.168.1.51    255.255.255.0   UG    0      0        0
>>> eth0
>>> 192.168.0.0     *               255.255.252.0   U     0      0        0
>>> eth0
>>> 169.254.0.0     *               255.255.0.0     U     0      0        0
>>> eth0
>>> default         192.168.1.1     0.0.0.0         UG    0      0        0
>>> eth0
>>> software at warsaw's password:
>>>
>>>
>>> Thanks,
>>>
>>> Michael
>>>
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