Re: [chromium-dev] How to stop chromium from calling home

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Keith I Myers

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Feb 8, 2018, 12:03:57 PM2/8/18
to lou...@gmail.com, Chromium-dev
You could add entries to your hosts file pointing all of those domains to 127.0.0.1

On Thu, Feb 8, 2018 at 11:30 AM, loudogz <lou...@gmail.com> wrote:
I'm running chrome in kiosk and incognito mode.  Is there a way to prevent chromium from calling home.  I noticed that it is calling the following links in the background:


Thanks in advance,

loudogz

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PhistucK

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Feb 8, 2018, 2:15:31 PM2/8/18
to lou...@gmail.com, Chromium-dev
Why does it matter that they are dynamic? You want to block them and HOSTS maps a domain name (not an IP address) to an IP address.
Unless you do not want to block them?

My guess is that for most of the cases, it "calls home" just for speeding up the actual request (in case such request is needed soon) by resolving its DNS entry (a DNS prefetch type of thing).


☆PhistucK

On Thu, Feb 8, 2018 at 8:27 PM, loudogz <lou...@gmail.com> wrote:
I tried that method but the IP addresses of all the request to google are dynamic.

Thanks for the idea.


On Thursday, February 8, 2018 at 9:03:57 AM UTC-8, Keith I Myers wrote:
You could add entries to your hosts file pointing all of those domains to 127.0.0.1
On Thu, Feb 8, 2018 at 11:30 AM, loudogz <lou...@gmail.com> wrote:
I'm running chrome in kiosk and incognito mode.  Is there a way to prevent chromium from calling home.  I noticed that it is calling the following links in the background:


Thanks in advance,

loudogz

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Mike Frysinger

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Feb 8, 2018, 2:22:03 PM2/8/18
to PhistucK, lou...@gmail.com, Chromium-dev
i assume there will also be update checks & API calls sprinkled about too
-mike

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PhistucK

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Feb 8, 2018, 4:52:40 PM2/8/18
to loudogz, Chromium-dev
Sounds like a bug, really. crbug.com is the right place for reporting bugs.


☆PhistucK

On Thu, Feb 8, 2018 at 11:22 PM, loudogz <lou...@gmail.com> wrote:
I guess chromium is not using hosts file.


# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

I did that the following above to the hosts file.  When I ping  maps.google.com it does resolve to 127.0.0.1 but chrome is still "phoning" home when I trace it using tcpdump.


☆PhistucK

Keith I Myers

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Feb 8, 2018, 4:56:41 PM2/8/18
to Louie Valderrama, Chromium-dev, phis...@gmail.com
You may still see the connection attempt in a TCPdump but the connection is likely resolving to 127.0.0.1. If you did a dump on the router, you should not see that traffic at all. It is possible you need to restart networking or even reboot the box after you make the change to the host file.

As far as I know, it is not possible for a application to bypass the hosts file without implementing a full network stack. 

On Thu, Feb 8, 2018 at 4:22 PM, loudogz <lou...@gmail.com> wrote:
I guess chromium is not using hosts file.


# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

I did that the following above to the hosts file.  When I ping  maps.google.com it does resolve to 127.0.0.1 but chrome is still "phoning" home when I trace it using tcpdump.


On Thursday, February 8, 2018 at 11:22:03 AM UTC-8, Mike Frysinger wrote:


☆PhistucK

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Peter Kasting

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Feb 8, 2018, 4:58:33 PM2/8/18
to lou...@gmail.com, Chromium-dev
On Thu, Feb 8, 2018 at 8:30 AM, loudogz <lou...@gmail.com> wrote:
I'm running chrome in kiosk and incognito mode.  Is there a way to prevent chromium from calling home.  I noticed that it is calling the following links in the background:


This seems surprising.  Do net-internals traces show you enough detail to determine the cause of these requests?  These look less like something triggered from Chrome ("maps.google.com" doesn't even appear in non-test portions of Chrome's executable code) and more like something from an extension or webpage.

PK

Ryan Sleevi

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Feb 8, 2018, 5:06:30 PM2/8/18
to keithiok...@gmail.com, Louie Valderrama, Chromium-dev, PhistucK
On Thu, Feb 8, 2018 at 4:54 PM, Keith I Myers <keithiok...@gmail.com> wrote:
You may still see the connection attempt in a TCPdump but the connection is likely resolving to 127.0.0.1. If you did a dump on the router, you should not see that traffic at all. It is possible you need to restart networking or even reboot the box after you make the change to the host file.

As far as I know, it is not possible for a application to bypass the hosts file without implementing a full network stack. 

Chrome has its own DNS resolver, thus implementing that component of a network stack (i.e. an alternative to the system APIs). It does, however, attempt to respect the hosts file, but there can always be bugs.
 

On Thu, Feb 8, 2018 at 4:22 PM, loudogz <lou...@gmail.com> wrote:
I guess chromium is not using hosts file.


# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

I did that the following above to the hosts file.  When I ping  maps.google.com it does resolve to 127.0.0.1 but chrome is still "phoning" home when I trace it using tcpdump.

As noted, ensure you restart Chrome. For example, it does cache DNS results, so changing your host file may not immediately cause propagation of updates (we have a filewatcher, but even the system can delay reporting changes).

If you're still seeing issues, please file a new bug at https://crbug.com/new  and include a chrome://net-export trace as detailed at https://dev.chromium.org/for-testers/providing-network-details

Note that DNS blocking is not necessarily a reliable mechanism in today's Internet, as systems like HTTP/2 and QUIC allow for connection coalescing multiple origins on a single connection, HTTP/2 PUSH allows for the delivery of inter-origin resources, and, in the future, Web Packaging may allow for multi-origin delivery of resources. A combination of DNS blocking as well as utilizing the Chrome Extension webRequest API can give more robust blocking. However, as you stated you're using Kiosk+Incognito, it may be that Extensions are not allowed - in which case, you should file a feature request for the Kiosk and Extensions team to investigate.

Mike Frysinger

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Feb 8, 2018, 5:07:53 PM2/8/18
to Keith I Myers, Louie Valderrama, Chromium-dev, PhistucK
i don't know what you're defining as "full network stack", but if you mean IP/TCP/UDP, that's not true.  the only thing respecting /etc/hosts is the resolv library code often provided by the C library (e.g. glibc or ISC's bind library).  if you aren't using that to do the DNS resolution, then it's trivial to also not support /etc/hosts.

fairly certain cronet (Chromium's network code) handles DNS resolution itself and only requires socket support on the host (which handles UDP/IP traffic).  although the code indicates that it handles /etc/hosts parsing.

a simple Google search for "chrome /etc/hosts" suggests there are number of reasons you might see this behavior, including caching.  please try that search and various suggestions for mitigation.
-mike

On Thu, Feb 8, 2018 at 4:54 PM, Keith I Myers <keithiok...@gmail.com> wrote:
To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/chromium-dev/CAEKDPcFT9rH5vHiw1-LnExwv7w%2B100cJniN6AcYuuEdGFmFxJA%40mail.gmail.com.

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