[PLUG] Internet access certificate issues

Denis Heidtmann denis.heidtmann at gmail.com
Sun Sep 17 23:36:44 UTC 2017


Thanks for your reply.  I am afraid that some of your advice goes over my
head, but I checked your your link for flushing the DNS cache.  Problem:

/etc/rc.d/init.d/nscd restart
bash: /etc/rc.d/init.d/nscd: No such file or directory

I am running Ubuntu 16.04.

-Denis


On Sun, Sep 17, 2017 at 12:17 PM, Mike C. <mconnors1 at gmail.com> wrote:

> On 9/16/17 12:00 PM, plug-request at lists.pdxlinux.org wrote:
> > Where does DNS poisoning occur?  Since it was just local to my machine
> (no
> > general complaints noticed), then something local must have been hacked.
> > This could have been either my router or my modem, since my laptop
> > connecting via wireless to the router also had the problem.  The modem
> was
> > reset a few times during my contact with Comcast's technician, so it
> could
> > have been the modem if reset clears the cache.
> >
> > This whole thing is above my pay grade. Bottom line, if it recurs, what
> > should I do to find out what is happening?
>
> DNS poisoning initially occurs at the DNS server. An untrusted fake name
> record is introduced and then is cached in the DNS server and served to
> any unwitting entity that makes a DNS A record lookup for a hostname/fqdn.
>
> This is unlikely to be of a nefarious nature and far more likely to be
> caused by crappy code in the airRouter. I did tech. support work for a
> local manufacturer of lower-end APs that ran open source based software.
> Oh, the DNS & DHCP nightmare problems I could tell you about.
>
> I did a quick Google on this and found that people experienced similar
> problems with the Cisco RV130. If I recall the fix was a config change.
>
> I don't know if the Comcast modems run a DNS caching server. I doubt it,
> but maybe. I've been using a dns caching server on my linux boxen for
> many years. Now many linux distros come with dnsmasq installed and it
> runs at startup by default.  I think modern versions of MS Win also do
> this.
>
> So, what you do if this happens again? Here's what I would do.
>
> 1. Flush the dns cache on your computer and then try again. Here's how
> to do it on all OSs.
> https://www.techiecorner.com/35/how-to-flush-dns-cache-in-
> linux-windows-mac/
>
> 2. If problem persists, plug directly into the modem and try it again.
>
> 3. If problem persists, edit the /etc/resolv.conf file, add the Google
> nameserver addresses and try again.
> nameserver 8.8.8.8
> nameserver 8.8.4.4
>
> *NOTE: This is only temporary and will be overwritten upon the next DHCP
> renewal unless you edit the dhcp config file so that it doesn't request
> DNS entries or disable DNS on the Comcast modem.
>
> 4. If problem still persists, which I suspect is highly unlikely, then
> I'd probably start looking at either running some heavy duty malware
> software on your pc or wiping it and re-installing the OS from scratch.
>
> HTH!,
>
> Mike
>
>
>
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