How to flush DNS cache in FatDog?

[Neo_78]

How do you flush DNS cache from the terminal in FatDog?

Can you flush the cache as a non-root user?

Thanks for your feedback!

[williams2]

How do you flush DNS cache from the terminal in FatDog?

In BionicPup,

Code: Select all

echo 3 > /proc/sys/vm/drop_caches

Should be the same for FatDog.

Can you flush the cache as a non-root user?

Not in BionicPup
should be the same for FatDog.

Code: Select all

cache-clear: line 6: can't create /proc/sys/vm/drop_caches: Permission denied

Depends on the permissions that are set.
The files in /proc/ are not really files.
Reading and writing in /proc/ is communicating directly with the kernel processes.

EDIT: There is not much point in clearing the cache space.
The space in the cache is instantly available to any process that needs it.

[williams2]

Which does not answer the question.

I don't think dns resolv has much caching.
which is why there is dnsmasq

AFAIK, if you are running your own dns server it should have options to configure and clear dns caches

I run dnsmasq. There is probably a command to clear the dns cache.
What I do is simple and crude but it works.
I just stop dnsmasq and restart it. Like this:

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#!/bin/sh
killall -q dnsmasq
dnsmasq -r /etc/resolv2.conf

[Neo_78]

Thanks @williams2. The echo command unfortunately requires sudo privileges.

[jamesbond]

How do you flush DNS cache from the terminal in FatDog?

You don't.

Fatdog does not cache DNS. Applications do. Routers do.
You need to tell the applications / routers that you're using to drop their DNS caches (like the example given by @williams2 - if you run dnsmasq).

Can you flush the cache as a non-root user?

You have a lot of questions asking how to do this and that as "non-root".
I really don't understand where you are coming from.
You keep saying you want to do it that way for "for security reasons", but I fail to see what your "reasons" are.

Firstly, If you are so concerned about running as "root", then why you choose an OS that, by default, run as root? Almost every flavour of Linux OS you can find in this forum run as root by default - and that is by design. It is not an accident that we run as root. We choose to run as root, because while we are aware of the risks, we are also aware the benefits and consider that the benefits far outweigh the risks.

Now, I completely understand if you disagree with our assessment of the risk/benefit ratio, but again, if you are so adverse to running as root, then, there are plenty other nice, good and reliable Linux OS that don't run as root by default; and perhaps they are more suitable for you. Some are even located in this forum.

Secondly, most of the things that you're asking to do as "non-root" are privileged operations.
These operations can have a wide-ranging impact, which the designer of the Unix (not only Linux, but all OS derived from Unix such as Linux, BSD, macOS, etc ...) have, for the better or worse, constrained so that they can only be used by knowledgeable person who knows the system inside out. That is, the "administrator" of the system - which is "root".

By asking how to do privileged operations as non-root user, you are not improving the system's security. In fact, it's the opposite.

Consider this: if a non-root user can do what only "root" is supposed to be able to do, then it means that non-root user has root's powers; hence, for all intents and purposes the non-root user __is__ root. Instead of having only one, controlled, "privileged user" that can do "privileged operations", now "every user" can do those "privileged operations". (This is the reason why sudo is such a stupid idea).

Other people describe the situation where a non-root user can do root-only stuff as a "privilege escalation" bug, and it is considered as one of the more serious vulnerability problems. Please explain to me, why you purposely want this to happen, then?