Re: Standardizing NO_NETWORK and USE_SYSTEM_DEPS environment variables

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Celeste Liu <[email protected]> writes:

>> 1) NO_NETWORK -- if it's set to a non-empty value, it requests that
>> programs don't access the (TCP/IP) network.
>=20
> It may be better to be named NO_INTERNET. Network is a confusing word in =
Linux=20
> world. They can refer to something from only Internet to any protocols in=
=20
> network subsystem, even include AF_NETLINK... I have been asked why my ud=
ev is=20
> broken when my program is in a netns many times. Systemd also have to inf=
orm=20
> this point in their document of PrivateNetwork. So use more limited word=
=20
> Internet to avoid this.

You are right.  While my initial reaction to NO_NETWORK was positive, I
have realized that there are subtle issues that is really hard to
resolve.  I considered adding support for NO_NETWORK to GNU InetUtils
but I am beginning to feel that even NO_NETWORK has the same critical
concerns that USE_SYSTEM_DEPS has: What exactly should NO_NETWORK mean
to a package?  What can it assume and what MUST it fail on?

=2D Can it use localhost IP connectivity?

=2D TCP?

=2D Multicast?

=2D Can it rely on non-DNS /etc/hosts name resolution working?

=2D Can it rely on /etc/services being able to lookup network service
  names?

=2D Is it allowed to inspect routing table on the system?

etc

Disabling all of those functionality when NO_NETWORK is probably not
what was intended, right?

When doing self-checks for 'ftp' and 'ftpd' it makes sense to start your
newly built ftpd and test interop it against your newly built ftp
binary.  I don't think the intention is to forbid this.

/Simon

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