kris-nova
Network Instrumentation and TCP File Descriptor Hijacking
So I want to be clear. This work is very much in the "fantasy" stage. I haven't ran this at scale, and there is a lot I would do before I blindly rolled something like this out. As far performance impact, it obviously would depend on how it's implemented however I think a reasonable amount of "tracer packets" being sent out every 15 seconds or so to each hop shouldn't be too disruptive to the network, or to the host machine issuing the request. In other words if you take the `ptrace(2)` concern out of the equation (this is the big one in my mind) its going to be negligible.
> And, the rootkit question, how would eBPF notice you doing this?
I suppose it would depend on what your strategy with eBPF is and where you were looking. Reminding yourself that the pidfd_getfd and pidfd_open functions are system calls, I think any modern Linux auditing system would see something like this "a mile away".
In other words, I don't see somebody using this tactic to steal FDs in production without quickly alerting most security systems. I suspect there would be ways of hiding this however... https://github.com/krisnova/boopkit...
Network Instrumentation and TCP File Descriptor Hijacking
I could fill pages with the anecdotes, specific examples, and my personal speculation on why this is but i can just gloss over the details and skip to the takeaway: LSD has made my life net better.
Another point I am trying to drive home is that this is what I would consider an “incomplete” or “immature” take. For example the authors anxiety is likely stemming from some organic experiences either traumatic, economic, physiological, or psychological — getting to the bottom of those and surfacing the patterns themselves is one of the great benefits of this chemical. I’d love to see this author examine their experience and ask where the anxiety is coming from.
You have to face your fears and anxiety before you can understand them — before you can conquer them.
I’m just glad this forum is finally talking about this topic. More psychedelics here please.
In the U.S. this likely means losing your healthcare and missing your children’s tuition payments — and even your housing. Your visa if you’re immigrating, etc.
The only people who have enough psychological security to do this are the ones who don’t actually depend on their jobs for maintaining their current standard of living.
In a perfect world this would be great advice for everyone, however given the political and economic culture of the U.S. this is pretty horrible advice for a marginalized person. Our labor laws don’t support this behavior for a reason — and if “push comes to shove” every corporation in Silicon Valley will air on the side of modern labor laws (or lack there of).
But yes we should all also be adding links in our writing and publishing on our own platforms.
Observing and Understanding Backlog Queues in Linux
Men who change jobs: literally articles inventing new vernacular stemming from the mental gymnastics required to justify the hypocrisy — men aren’t incapable because they change jobs — they are prodigy — men aren’t untrustworthy for changing jobs — they are taking nonlinear career paths because of the uncertainty in the market
Aurae: Distributed Runtime (FOSDEM 2023 Video)
Is Twitter Operationally Okay?
I’ve heard a lot of reports of auth breaking, posts failing, errors, and 4XX and 5XX. Are there any good reports or neutral resources that have been probing their infrastructure for uptime and availability?
Every subdomain will get a single tweet before Twitter propagates the URL, shadow band your tweet, and blocks the URL moving forward.
Have fun folks.
I was able to get a single tweet in using hackyderm.io and my account is now “shadow banned”. Meaning I can view my tweet, but nobody else can. Which is exactly what Twitter has promised not to do, and what we use as a tactic on Reddit to keep shitty content at bay. It means that from the posters perspective everything looks “fine” and their content is just not getting any engagement.
Twitter has flagged all the major Mastodon servers as malware
URLs containing any of the popular Mastodon servers are rejected by the Twitter API. Profile bios and URLs are now rejected if a user attempts to change them. All the major Mastodon sites are flagged, and Twitter is even checking 3XX redirects, transparent proxies, and URL/link shortening services for Mastodon related responses.
I can say with certainty that Ruby specifically was not the bottleneck in our case. I do think that the rails paradigm can often lead to interdependent systems. We see this at GitHub and we also see this in Mastodon. Service A will do reads/writes against the same tables in the database that Service B also does. When service A is moved to an isolation zone, it can still impact Service B's performance.
In other words, I think any stateful framework with the flexibility that Ruby on Rails encourages bad behavior that can contribute to a noisy neighbor problem.
The point I am trying to drive home is that I agree. I can confidently say that Ruby on Rails is not the culprit in our case. To be honest I just ignore anyone who is quick to point fingers and assign blame either technically or personally.
Sorry hacker news got you down. If it helps my family and I are making Sunday morning pancakes with my puppy Björn today and we are all wishing you the best day ever.
So to be clear, we did try to "offline" a drive from the ZFS pool just to see if this was a viable path. The ZFS pool was set up a few years ago and has gone through a few iterations of disks. The mirrors were unbalanced. We had pairs of drives of one manufacturer/speed mirrored with pairs of drives from another manufacturer/speed. We know this configuration was wrong, again we didn't intend for our little home lab to turn into a small production service.
I think after spending a few hours trying to "offline" the disk, and then repairing the already brittle ZFS configuration to getting the database/media store back to a "really broken and slow but still technically working" state we just decided to pull the plug and move to Hetzner. Offlining the disk caused even more cascading failures and took about 30 minutes just for the software. We could have technically shut down production to try without the database running on it, but at that point we decided to just get out of the basement.
If it would have been as easy as popping a disk in/out of the R630 (like one would imagine) we would have certainly done that.
To be honest I am still very interested in performing more analysis on ZFS on a 6.0.8 Linux kernel. I am not convinced ZFS didn't have more to do with our problems than we think. I will likely do a follow up article on benchmarking the old disks with and without ZFS in the future.
zfs-2.1.4-1 zfs-kmod-2.1.6-1 6.0.8-arch1-1