Re: Simple way to securely access remote machine that's behind a NAT?

[mlelstv%serpens.de@localhost (Michael van Elst)]

acruhl%gmail.com@localhost (Andy Ruhl) writes:

>On Tue, Sep 25, 2018 at 8:49 AM David Young <dyoung%pobox.com@localhost> wrote:
>> I added UDP encapsulation to gre(4) in NetBSD specifically to pierce NAT
>> firewalls, however, I don't know if Linux also has a UDP encapsulation
>> for GRE.

I haven't seen a Linux kernel implementation of RFC8086 (GRE in UDP),
but there is the Multi-Path Tunnel project on github that implements
it including the draft multipath extension for it.

>This is off topic, but it was alluded to earlier:

>I think it's possible for a router to forward an IP protocol inward
>via NAT, such as GRE? Or am I mistaken?

NAT sessions are usually only created dynamically for outgoing traffic and
since GRE has no session boundaries it's likely to be timed out then. But
a static NAT rule should be fine.

But then, some NAT routers will just drop GRE.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."