[VoIP] ENUM (Linux DNS) and Linksys WRT54GS

Sat Jan 5 16:44:25 CST 2008

Chad Perkins wrote:
>
> True.  Most consumer grade routers offer their own LAN IP address to DHCP clients as DNS server (in addition the DHCP server and default gateway) and perform "proxy" DNS, which generally is a good thing as you do not need to keep track of DNS server changes, infrequent as they may be (because the router is going to get that information as part of it's DHCP client lease from the ISP).
>   
I have, and had a less complex situation
For quite some time I was using the router gateway address for DNS, and 
all worked well. I even moved from a 4 port Linksys cheapie to an 8 port 
one, as the 4 port one had an issue with SIP, where conversations longer 
than about 18 minutes through SIP either with Vonage ( my ATA is on the 
LAN side ) or Stanaphone through Asterisk would just die, killing the 
conversation and all internet access on the LAN. Sometimes simply 
terminating the VOIP would allow restoration, and at other times I would 
have to power cycle the router. The 8 port model fixed that. Some 
invisible firmware differences. But I digress. With BOTH routers 
Asterisk was happy and could find its way to std.ckts.info and elsewhere 
when I needed to wget an update.
Then one fine sunny day it stopped. It took me some time to figure out 
what was wrong, but I managed to bumble through it and once I pointed 
the box to the ISP DNS, all has been fine since. I have seen this with 
other CNET installations I support remotely as well.
Interestingly just today, I am no longer able to send e-mail through 
Comcast, or any other SMTP port 25. I am currently using my gmail smtp 
at port 587
Kirt and I assume Comcast has fat fingered a router somewhere, as the 
smtp name resolves, but it can't be reached with telnet on the Linux box.

These damn machines are starting to revolt.
Listen for a knock on the door. The end is near.

John Novack

> As a result many folks use the routers LAN IP address as the DNS server on 
> statically configured machines to keep things clean and simple (clients will behave, 
> DNS-wise, the same as DHCP clients as they are using same servers, and they 
> don't have to worry about DNS server address changes, etc.).  I fall in this category.
>  
>   
>> But, by using DHCP, the /etc/resolv.conf is overwritten by whatever
>> information your DHCP server provides.  
>>     
>
> Agreed.
>
>   
>> If I understand you correctly,
>> it is your router that is acting as a DHCP server, and it is handing
>> out its own IP address as being the DNS server.
>>     
>
> Close.  In addition to running Asterisk, the linux box is the DHCP server (and tftp 
> server, I have some Cisco phones that have advanced needs).  The DHCP server 
> function is the only thing I took "off" the router.
>  
>   
>> So, I zero in on the DHCP server.  Two thoughts occur to me.  Either
>> (a) the DHCP server doesn't know how to deal with NAPTR DNS resource
>> records, 
>>     
>
> DHCP clients get their leases from the linux box (the DHCP server), it gives them the 
> routers LAN IP address for default gateway and DNS server.  The linux box performs 
> no DNS service except for itself.
>
> DHCP servers per se don't do DNS, unless of course it is also a DNS server.  And 
> given the way this box is now behaving, the problem seems to affect A records too.
>
>   
>> or, (b) it doesn't have an upstream DNS server that it queries
>> that responds in a timely manner.
>>     
>  
> I would say yes to this one, except the Windows clients are configured with the same 
> LAN IP address for the DNS server and still work fine.  
>
> I'm about ready to fire up Sniffer Pro and see what the linux box is actually doing on 
> the wire and compare that to a working machine!!
>
> Chad
> 1-955-9924
>
>  
>   
>>> -----Original Message-----
>>> From: voip-bounces at ckts.info [mailto:voip-bounces at ckts.info] 
>>> On Behalf Of Chad Perkins
>>> Sent: Saturday, January 05, 2008 10:57 AM
>>> To: Voice Over IP Tandem for Analog Switches
>>> Subject: Re: [VoIP] ENUM (Linux DNS) and Linksys WRT54GS
>>>
>>> The problem seems to be in Linux.  I think what's happening 
>>> is that Enumlookup (a DNS query) is timing out before getting 
>>> an answer (Asterisk does hang for a minute on the EnumLookup).
>>>
>>> The larger problem I think is even pinging is very slow by name
>>> (i.e. std.ckts.info).  Connections made by IP address are just as
>>> fast as before, even to the same site(s).  This problem seems to be
>>> effect all applications that use DNS, except nslookup!!?
>>>
>>> Chad
>>>
>>> On 5 Jan 2008 at 1:02, Greg Blakely wrote:
>>>       
>>>> Chad,
>>>> I can email you a copy of my "dc" macro.  It works on those 
>>>>         
>>> versions 
>>>       
>>>> of Asterisk 1.4 that don't have a broken ENUM function.  
>>>>         
>>> Let me know.
>>>       
>>>> Greg
>>>>         
>>>>> -----Original Message-----
>>>>> From: voip-bounces at ckts.info [mailto:voip-bounces at ckts.info] On
>>>>> Behalf Of Chad Perkins Sent: Friday, January 04, 2008 10:54 PM
>>>>>
>>>>> I'm in day 3 of not being able to make calls on CNET due to a
>>>>> failure of Linux DNS after a reboot of the box and replacing the
>>>>> VeriZon DSL router with a WRT54GS...
>>>>>
>>>>> Tonight I flashed the firmware on the Linksys from 1.50.6 to
>>>>> 1.52.2 (the latest?) to no avail.
>>>>>
>>>>> I'm off to bed now, but if any you Linux "gurus" think you can
>>>>> figure how how to fix this I'd love to hear from you tomorrow
>>>>> (1-955-9924)! Chad
>>>>>           
>
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>   

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