[Unbound-users] error: tcp connect: No route to host

Babu C babscontact at rediffmail.com
Sat Jan 15 07:10:03 UTC 2011

Hi,Thanx for the reply and I am still facing the same issue, one more thing I wanted to add is I am having a pf firewall on the same machine. Everything works fine as long as the DSL connection is up, but once the DSL goes down and come back everything is back except unbound and its damn frustrating to be unable to resolve it. I never had to face it with old version before I updated.
Still waiting to hear from othersDotfish

On Thu, 13 Jan 2011 16:37:13 , "W.C.A. Wijngaards" <wouter at NLnetLabs.nl> wrote

Hash: SHA1

Hi Dotfish,

It would be interesting to hear from others, as I do not have experience

with connection failures.

On 01/10/2011 06:00 AM, Babu C wrote:

> I am  running unbound for a year and found its very useful to speedup

> browsing for my network and its users. 

Thanks :-)

> I have recently upgraded my OS and Unbound, since then I am facing a

> particular problem, when the ADSL connection goes down and come back

> Unbound refuses to resolve the queries till I restart Unbound. I never

> faced this issue with previous unbound version. I tried googling

> and couldn't find any thing to mitigate my problem.


> OS - FreeBSD 8.1

> Unbound :  Unbound 1.4.7

Since unbound 1.4.7 there is a change in the timout code, blog here:


It means that if the issue was longer than a couple of minutes, unbound

will start to probe once every 15 minutes.  You would have to wait for

(up to) 15 minutes (per domain) before unbound notices the link coming

up again.  You likely did not want to wait and the restart cleared the

timers.  (there is also the flush_infra all command in 1.4.7 if you do

not want to lose the other cache contents).

If you experience these issues more frequently ( :-( ), you could

consider the config option:  infra-host-ttl: 60

(or another value lower than the default 900 seconds).  This makes

unbound forget the connection problem, or retry a destination sooner.

It would likely cause unbound to come back up after a minute or so, if

you experience another outage.

> When I started noticing this issue, I increased the verbosity to 3 in

> unbound.conf and found the following error logged 

> unbound: [847:1] error: tcp connect: No route to host

> Kindly help me to resolve this issue

FreeBSD tells unbound that the connect(2) syscall gets the errno: No

route to host, when it (in desperation?) tries to connect over TCP to a

remote nameserver.  Look at the route table (netstat -r).  Likely your

connection is down and the upstream route is withdrawn?  Or is this a

different problem?

Best regards,



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