# nonlistening services (DNS issue?)

## necron

so my net services seem to be all screwed up.  dhcp requests seem to be fine and all the services actually start, but then i can't resolve hostnames, and a port scan shows that only my tor service seems to be listening...then somehow it seems to correct itself after several minutes.

is this something that is fixed by using a different DNS?  my isp (comcast) didn't offer much help past "run ipconfig", but they did claim to only have one server handling ALL of their DNS requests  :Confused: 

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## Hu

We need more details.  What was the network topology relation between the affected machine and the machine running the port scan?  Did tcpdump confirm that the port scan arrived at the affected machine?  Did netstat -na confirm that the services were listening on your public IP address (or on the wildcard address)?  What is in your /etc/resolv.conf during the time when the affected machine has no name service?  Are the contents the same after name service starts working?

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## necron

resolv.conf was just comments telling me that dhcpcd generated the file, and after things started working it contained a domain name and a couple comcast nameservers.

as for netstat and tcpdump i didn't really know about netstat and i didn't have tcpdump installed.  all i really did was "nmap 127.0.0.1", and based on that i thought it might be a dns issue since tor was configured to use its own dns and i had things either bitching about nameservers (i.e. nmap) or resolving hostnames.  it's also not the first time i've seen comcast crap out like that, and when it did i could browse the web fine through tor while the other guy, on the same network, couldn't get anything without a numeric ip address (which i would have tried if i'd known any off hand)

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## Hu

If no name servers are listed in /etc/resolv.conf and the interface is up, then you need to contact your DHCP server administrator to have the DHCP daemon configuration changed.  You could also just declare the upstream provider to be useless and force a set of DNS servers via /etc/conf.d/net, but then you will be responsible for changing the values if upstream ever renumbers their servers.

If the interface is not up, you need to wait for it to finish initializing.  Some DHCP servers are extremely slow to issue valid leases, so if you have background initialization enabled, the rest of the system can be in a ready state for quite a while before you finally get an address.

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## necron

i'm not so stupid that i wouldn't check whether i brought my interface up  :Wink: 

i did give tech support another crack after i came home to find my connection dead, and this time it occurred to me that the cable they hooked me up to was going through a splitter.  my /var/log/messages and their diagnostic software seemed to be saying that my connection was cutting out, so i just got rid of the splitter...not really sure why i didn't just try that in the first damned place...

now i suspect i might have just had a weak signal since things worked fine after bypassing it.  and now i have more coaxes than i know what i'll ever do with

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