Re: Strange behavior with directives ProxyRemote and NoProxy

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Hello,

On Fri, May 5, 2023 at 9:22 AM Carsten Klein <c.klein@xxxxxxxxxxx> wrote:
>
> Important(?) side note: through DNS the server can only resolve
> local/intranet names and addresses. The DNS refuses to resolve
> external/Internet names and addresses.

Unless NoProxy contains only domain names (e.g. ".mycompany.local")
which can be compared verbatim, there will be a DNS resolution for the
requested host. And if that DNS resolution fails, NoProxy does not
apply (i.e. ProxyRemote is used).

>
> According to the docs, configuring ProxyRemote and NoProxy should be
> quite simple:
>
> # All requests go through the company's proxy
> ProxyRemote "*" "http://10.5.10.20:8080";
>
> # Direct requests to all intranet hosts
> NoProxy ".mycompany.local" "10.0.0.0/8"

So here if the requested host does not end in ".mycompany.local", it
will be resolved and compared to the network address.
Your configuration depends on DNS, more exactly it depends on DNS to
work at least for local/intranet hosts (failures on remote ones
shouldn't be an issue but looks fragile and not optimal. It's broken
if the DNS does not fail but returns a 10/8 address for whatever
reason though).

I would try to only set:
  NoProxy ".mycompany.local"
to exclude DNS from the game and see what happens for requests to this
domain at least. If it works for those and you still need to also
match "10.0.0.0/8" for requests using local IP addresses directly or
other/unknown/unlistable local domain names, you probably should have
a look at how hosts are resolved on the local DNS when requests are
misdirected.


Regards;
Yann.

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