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Something to add: use proxychains to ensure that the requests of all apps go through the proxy. A lot of applications don't have good proxy support, or have nothing at all. If you configure proxychains with the SOCKS proxy provided by this script, then you can do "proxychains my-command-that-doesnt-use-proxy" and it will automatically patch the libc calls to use the proxy properly.
Good suggestion. Added it to the README as an optional addition.
I don't really get what the definition of "network" is here, clearly the box has network access since it is SSH'able. Could you give an example of a situation when this is used?
You could have a bridge (e.g. with an IDS or a packet filter) with a management interface on a separate VLAN, or which requires management via a physical cable of some sort. But the bridge could also intercept traffic to port 22 and redirect it to itself. Personally, I resort to Wireguard instead being the only reachable port.
"Network access" as in outgoing requests to public web.
e.g. you can't curl google.com
I've used this code in CTF competitions and Blue Team exercises where some machines behind a VPN don't have outgoing network access.
(Sometimes it's just simpler to organize this way, sometimes it's deliberate for security purposes.)
So restricted HTTP access, but wide open SSH? Do people commonly restrict only HTTP/HTTPS but leave other ports unrestricted?
This would be a common setup. They allow SSH ingress so that the server can be managed or provisioned with something like Ansible. However, they block all other unused ingress ports, as well as any egress that does not contribute to the function of the server. Also common would be a bastion or VPN to get to the network where SSH is accessible. A mistake is to have SSH accessible to the entire corporate network, which is all too common.
no wide open ssh, it's a machine that can talk to it that can also talk out to the wider internet. (A proxy).
Yeah, well, not only HTTP*, but actually whitelisting whatever outgoing connection you may need.
https://github.com/stripe/smokescreen
Suppose you configured your webserver to run with limited privileges so as if someone hacks it it has limited access. Suppose it still has access to DB and stuff. Well, filtering outgoing connections makes harder to exfiltrate the data OR hop to another hosts. And then you can monitor failed outgoing requests to be able to act/investigate when that happens.
Couldn't an attacker exfiltrate over ssh or over an incoming HTTP connection instead of an outgoing? Or is this a defense-in-depth thing, not meant as a "hard stop"?
The name, Airgapt - "airgapped" apt, is also a little "weird". When I work on air gapped devices it normally involved bringing DVDs and physically going to a datacenter.
Agreed :) That's why I put it in "quotes"
Can you propose an alternative / more accurate name?
I'd rather not :-)
Naming things is hard. I love the project though, not because I need it, but it proves one of my point: "If you didn't want me to be able to do X, then you shouldn't have allowed SSH access".
I think the name is quite apt (:
Not OP, but some air-gapped servers can be connected to from a private "trusted" network, but are otherwise unable to connect to the internet or elsewhere. Perhaps that's what OP means?
I wish companies would hurry up and move away from "trusted" networks and move onto zero trust.
> some air-gapped servers can be connected to from a private "trusted" network
Erm ... mate....
A device is either air-gapped or it isn't. The clue is kinda in the name.
Yes, I know gov/mil networks use data-diodes, but that's a different kettle of very expensive fish which is certified to EAL6/7.
For everyone else, air-gapped means what it says on the tin.
Pseudo air-gapping via firewall rules is not air-gapping, its called writing ACLs.
Bingo. Air-gapped machines, by definition, have no connection to each other. Not so much as an audio cable between them. Everything that goes back and forth is manually transferred, either by eyes-on-one-screen-hands-on-the-other-keyboard, or by sneakernet typically of media which may be inspected at yet a third station en route.
This is a proxy or a bastion host, no more, no less. Calling it an airgap, even in "scare quotes", is clownishly terrible and serves no purpose beyond polluting the language.
correct - I think people are getting confused - not sure how, since the name is very descriptive
Exactly. These "trusted" machines still have security vulnerabilities that you would like to patch though :)
Isn’t this typically called an ssh bastion?
Looks like :)
https://github.com/ovh/the-bastion
Though after looking into it more, it seems to me like bastions usually aren't used for reverse proxy / SOCKS like this.
Usually bastions are just allowing one SSH server on your VPC/network and every SSH connection going through it.
I still actually haven't found similar projects to mine.
I couldn't find the license for it. Is it open source? If so what license?
I added MIT license now :)
All comments & suggestions / code reviews are welcome!