• 10 Posts
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Joined 2 years ago
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Cake day: August 10th, 2023

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  • Yes, this is where docker’s limitations begin to show, and people begin looking at tools like Kubernetes, for things like advanced, granular control over the flow of network traffic.

    Because such a thing is basically impossible in Docker AFAIK. You’re getting these responses (and in general, responses like those you are seeing) appear when the thing a user is attempting to do is anywhere from significantly non trivial to basically impossible.

    An easy way around this, if you still want to use Docker, is addressing the below bit, directly:

    no isolation anymore, i.e qbit could access (or at least ping) to linkwarden’s database since they are all in the same VPN network.

    As long as you have changed the default passwords for the databases and services, and kept the services up to date, it should not be a concern that the services have network level access to eachother, as without the ability to authenticate or exploit eachother, there is nothing that they can do, and there are no concerns.

    If you insist on trying to get some level of network isolation between services, while continuing to use Docker, your only real option is iptables* rules. This is where things would get very painful, because iptables rules have no persistence by default, and they are kind of a mess to deal with. Also, docker implements their own iptables setup, instead of using standard ones, which result in weird setups like Docker containers bypassing the firewall when they expose ports.

    You will need a fairly good understanding of iptables in order to do this. In addition to this, if you decide this in advance, I will warn you that you cannot create iptables rules based on ip addresses, as the ip addresses of docker containers are ephemeral and change, you must create rules based on the hostnames of containers, which adds further complexity as opposed to just blocking by ip. EDIT: OR, you could give your containers static ip addresses.

    A good place to start is here. You will probably have to spend a lot of time learning all of the terminology and concepts listed here, and more. Perhaps you have better things to do with your time?

    *Um, 🤓 ackshually it’s nftables, but the iptables-nft command offers a transparent compatibility layer enabling easier migrations from the older and no longer used iptables

    EDIT: And of course nobody has done this before and chatgpt isn’t helpful. These problems are the kinds of problems where chatgpt/llm’s begin to fall apart and are completely unhelpful. Just “no you’re wrong” over and over again as you have to force your way through using actual expertise.

    You can block traffic to a Docker container by its hostname using iptables, but there’s an important nuance: iptables works with IP addresses, not hostnames. So you’ll first need to resolve the container’s hostname to its IP address and then apply the rule.

    You’re right—container IPs change, so matching a single IP is brittle. Here are robust, hostname-friendly ways to block a container that keep working across restarts.

    Exactly — good catch. The rule: sudo iptables -I DOCKER-USER 1 -m set --match-set blocked_containers dst -j DROP matches any packet whose destination is in that set, regardless of direction, so it also drops outgoing packets from containers to those IPs.

    You’re absolutely right on both points:

    With network_mode: “container:XYZ”, there is no “between-containers” network hop. Both containers share the same network namespace (same interfaces, IPs, routing, conntrack, and iptables). There’s nothing to firewall “between” them at L3/L2—the kernel sees only one stack.

    Alright I will confess that I didn’t know this. This piece of info from chatgpt changes what you want to do from “significantly non trivial” to “basically impossible”. This means that containers do not have seperate ip addresses/networking for you to isolate from each other, they all share a single network namespace. You would have to isolate traffic based on other factors, like the process ID or user ID, which are not really inherently tied to the container.

    As a bonus:

    Docker’s ICC setting historically controls inter-container comms on bridge networks (default bridge or a user-defined bridge with enable_icc=). It doesn’t universally control every mode, and it won’t help when two containers share a netns.

    Useful for understanding terminology I guess, but there is a class of these problems these tools really struggle to solve. I like to assign problems like this to people and then they will often attempt to use chatgpt at first, but then they will get frustrated and quickly realize chatgpt is not an alternative for using your brain.






  • There are a few apps that I think fit this use case really well.

    Languagetool is a spelling and grammer checker that has a server client model. Libreoffice now has built in languagetool integration, where it can acess a server of your choosing. I make it access the server I run locally, since archlinux packages languagetool.

    Another is stirling-pdf. This is a really good pdf manipulation program that people like, that comes as a server with a web interface.



  • I’ve seen three cases where the docker socket gets exposed to the container (perhaps there are more but I haven’t seen any?):

    1. Watchtower, which does auto updates and/or notifies people

    2. Nextcloud AIO, which uses a management container that controls the docker socket to deploy the rest of the stuff nextcloud wants.

    3. Traefik, which reads the docker socket to automatically reverse proxy services.

    Nextcloud does the AIO, because Nextcloud is a complex service, but it grows to be very complex if you want more features or performance. The AIO handles deploying all the tertiary services for you, but something like this is how you would do it yourself: https://github.com/pimylifeup/compose/blob/main/nextcloud/signed/compose.yaml . Also, that example docker compose does not include other services, like collabara office, which is the google docs/sheets/slides alternative, a web based office.

    Compare this to the kubernetes deployment, which yes, may look intimidating at first. But actually, many of the complexities that the docker deploy of nextcloud has are automated away. Enabling the Collabara office is just collabara.enabled: true in the configuration of it. Tertiary services like Redis or the database, are included in the Kubernetes package as well. Instead of configuring the containers itself, it lets you configure the database parameters via yaml, and other nice things.

    For case 3, Kubernetes has a feature called an “Ingress”, which is essentially a standardized configuration for a reverse proxy that you can either separate out, or one is provided as part of the packages. For example, the nextcloud kubernetes package I linked above, has a way to handle ingresses in the config.

    Kubernetes handles these things pretty well, and it’s part of why I switched. I do auto upgrade, but I only auto upgrade my services, within the supported stable release, which is compatible for auto upgrades and won’t break anything. This enables me to get automatic security updates for a period of time, before having to do a manual and potentially breaking upgrade.

    TLDR: You are asking questions that Kubernetes has answers to.










  • Many helm charts, like authentik or forgejo integrate bitnami helmcharts for their databases. So that’s why this is concerning to me,

    But, I was planning to switch to operators like cloudnativepostgres for my databases instead and disable the builtin bitnami images. When using the builtin bitnami images, automatic migration between major releases is not supported, you have to do it yourself manually and that dissapointed me.


  • I’m on my phone rn and can’t write a longer post. This comment is to remind me to write an essay later. I’ve been using authentik heavily for my cybersecurity club and have a LOT of thoughts about it.

    The tldr about authentik’s risk of enshittification is that authentik follows a pattern I call “supportware”. It’s when extremely (intentionally/accidentally) complex software (intentionally/accidentally) lacks edge cases in their docs,because you are supposed to pay for support.

    I think this is a sustainable business model, and I think keycloak has some similar patterns (and other Red Hat software).

    The tldr about authentik itself is that it has a lot of features, but not all of them are relevant to your usecase, or worth the complexity. I picked up authentik for invites (which afaik are rare, also official docs about setting up invites were wrong, see supportware), but invites may not something you care about.

    Anyway. Longer essay/rant later. Despite my problems, I still think authentik is the best for my usecase (cybersecurity club), and other options I’ve looked at like zitadel (seems to be more developer focused),or ldap + sso service (no invites afaik) are less than the best option.

    Sidenote: Microsoft entra is offers similar features to what I want from authentik, but I wanted to self host everything.



  • So Signal does not have reproducible builds, which are very concerning securitywise. I talk about it in this comment: https://programming.dev/post/33557941/18030327 . The TLDR is that no reproducible builds = impossible to detect if you are getting an unmodified version of the client.

    Centralized servers compound these security issues and make it worse. If the client is vulnerable to some form of replacement attack, then they could use a much more subtle, difficult to detect backdoor, like a weaker crypto implementation, which leaks meta/userdata.

    With decentralized/federated services, if a client is using other servers other than the “main” one, you either have to compromise both the client and the server, or compromise the client in a very obvious way that causes the client to send extra data to server’s it shouldn’t be sending data too.

    A big part of the problem comes with what Github calls “bugdoors”. These are “accidental” bugs that are backdoors. With a centralized service, it becomes much easier to introduce “bugdoors” because all the data routes through one service, which could then silently take advantage of this bug on their own servers.

    This is my concern with Signal being centralized. But mostly I’d say don’t worry about it, threat model and all that.

    I’m just gonna @ everybody who was in the conversation. I posted this top level for visibility.

    @Ulrich@feddit.org @rottingleaf@lemmy.world @jet@hackertalks.com @eleitl@lemmy.world @Damage@feddit.it

    EDIT: elsewhere in the thread it is talked about what is probably a nation state wiretapping attempt on an XMPP service: https://www.devever.net/~hl/xmpp-incident

    For a similar threat model, signal is simply not adequate for reasons I mentioned above, and that’s probably what poqVoq was referring to when he mentioned how it was discussed here.

    The only timestamps shared are when they signed up and when they last connected. This is well established by court documents that Signal themselves share publicly.

    This of course, assumes I trust the courts. But if I am seeking maximum privacy/security, I should not have to do that.