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 

 

 

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