Hi,

We use dnsmasq 2.55 in our Linksys routers.  We have generally had few problems 
with dnsmasq, but recently one of our customers reported a failure that did not 
recover.

On the customer's router, the maximum number of dhcp clients is 50.  The 
customer happens to be a hotel and experienced a high usage rate and exceeded 
the 50 dhcp client limit.  As expected, the 50 active clients received their IP 
address and those over 50 did not.  However, the customer noticed that dns 
stopped working when this happened.  The CPU usage went to 50% (49.4% was 
logged to dnsmasq by top).  This may be 100% of single CPU as this is a dual 
CPU router.  The environment is a mixed environment of both IPv4 and IPv6... I 
believe we only use dnsmasq for IPv6 for the dns capability; ipv4 uses dhcp and 
dns capability from dnsmasq.  The customer goes on to say that dhcp renewals 
were not being handled as well.  Customer has also added that sometimes they 
see issue with only 30 active dhcp users or so.  Apparently it requires a good 
number of users before it happens... and it does not occur immediately.... 
Sometimes a few days or more before it happens.

I looked through some of your release notes and noticed some similarities on 
some bug reports, but did not see an exact match.  Does any of this make sense 
to you?  We tried reproducing this in our lab and were unsuccessful simulating 
the scenario.  We realize that our dnsmasq version is pretty old and a lot of 
fixes may have been applied since version 2.55.  If there is a good chance that 
the issues seen have been fixed in a later release, we will consider upgrading 
to a newer version.  If you could comment on the likelihood of a fix already 
being made, I would appreciate it.  Since we cannot reproduce the problem, we 
will likely have to apply a newer version (hopefully very stable) and have 
customer try it... something we would prefer to avoid unless we have some 
confidence that the problem may already be fixed in the newer release.

Thank you for your time.  I look forward to hearing from you.

Best Regards and thanks,

John Knight

JOHN KNIGHT
Senior Software Engineer

Belkin International

O +1 949 238 4543
M +1 949 351 1020
[Belkin-WeMo-Linksys]


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