What's a decent password length?

What's a decent length for a password?

I think it's pretty much agreed by now that longer passwords are, in general, better. And fortunately stupid complexity requirements are on the way out.

Reading the NIST password rules gives the following:

• User chosen passwords must be at least 8 characters
• Machine chosen passwords must be at least 6 characters
• You must allow passwords to be at least 64 characters

Say what? A 6 character password is secure?

Initially, that seems way off, but it depends on your threat model. If you have a mechanism to block the really bad commonly used passwords, then 6 characters gives you a billion choices. Not many, but you should also be implementing technical measures such as rate limiting.

With that, if the only attack vector is brute force over the network, trying a billion passwords is simply impractical. Even with just passive rate limiting (limited by cpu power and network latency) an attacker will struggle; with active limiting they'll be trying for decades.

That's with just 6 random characters. Go to 8 and you're out of sight. And for this attack vector, no quantum computing developments will make any difference whatsoever.

But what if the user database itself is compromised?

Of course, if the passwords are in cleartext then no amount of fancy rules or length requirements is going to help you at all.

But if an attacker gets encrypted passwords then they can simply brute force them many orders of magnitude faster. Or use rainbow tables. And that's a whole different threat model.

Realistically, protecting against brute force or rainbow table attacks probably needs a 16 character password (or passphrase), and that requirement could get longer over time.

A corollary to this is that there isn't actually much to be gained to requiring password lengths between 8 and 16 characters.

In illumos, the default minimum password length is 6 characters. I recently increased the default in Tribblix to 8, which aligns with the user chosen limit that NIST give.

Tribblix image structural changes

The Tribblix live ISO and related images are put together every so slightly differently in the latest m34 release.

All along, there's been an overlay (think a group package) called base-iso that lists the packages that are present in the live image. On installation, this is augmented with a few extra packages that you would expect to be present in a running system but which don't make much sense in a live image, to construct the base system.

You can add additional software, but the base is assumed to be present.

The snag with this is that base-iso is very much a single-purpose generic concept. By its very nature it has to be minimal enough to not be overly bloated, yet contain as many drivers as necessary to handle the majority of systems.

As such, the regular ISO image has fallen between 2 stools - it doesn't have every single driver, so some systems won't work, while it has a lot of unnecessary drivers for a lot of common use cases.

So what I've done is split base-iso into 2 layers. There's a new core-tribblix overlay, which is the common packages, and then base-iso adds all the extra drivers. By and large, the regular live image for m34 isn't really any different to what was present before.

But the concepts of "what packages do I need for applications to work" and "what packages do I want to load on a given downloadable ISO" have now been split.

What this allows is to easily create other images with different rules. As of m34, for example, the "minimal" image is actually created from a new base-server overlay, which again sits atop core-tribblix and differs from base-iso in that it has all the FC drivers. If you're installing on a fibre-channel connected system then using the minimal image will work better (and if you're SAN-booted, it will work where the regular ISO won't).

The next use case is that images for cloud or virtual systems simply don't need most of the drivers. This cuts out a lot of packages (although it doesn't actually save that much space).

The standard Tribblix base system now depends on core-tribblix, not base-iso or any of the specific image layers. This is as it should be - userland and applications really shouldn't care what drivers are present.

One side-effect of this change is that it makes minimising zones easier, because what gets installed in a zone can be based on that stripped-down core-tribblix overlay.

The SunOS JDK builder

I've been building OpenJDK on Solaris and illumos for a while.

This has been moderately successful; illumos distributions now have access to up to date LTS releases, most of which work well. (At least 11 and 17 are fine; 21 isn't quite right.)

There are even some third-party collections of my patches, primarily for Solaris (as opposed to illumos) builds.

I've added another tool. The SunOS jdk builder.

The aim here is to be able to build every single jdk tag, rather than going to one of the existing repos which only have the current builds. And, yes, you could grope through the git history to get to older builds, but one problem with that is that you can't actually fix problems with past builds.

Most of the content is in the jdk-sunos-patches repository. Here there are patches for both illumos and Solaris (they're ever so slightly different) for every tag I've built.

(That's almost every jdk tag since the Solaris/SPARC/Studio removal, and a few before that. Every so often I find I missed one. And there's been the odd bad patch along the way.)

The idea here is to make it easy to build every tag, and to do so on a current system. I've had to add new patches to get some of the older builds to work. The world has changed, we have newer compilers and other tools, and the OS we're building on has evolved. So if someone wanted to start building the jdk from scratch (and remember that you have to build all the versions in sequence) then this would be useful.

I'm using it for a couple of other things.

One is to put back SPARC support on illumos and Solaris. The initial port I did was on x86 only, so I'm walking through older builds and getting them to work on SPARC. We'll almost certainly not get to jdk21, but 17 seems a reasonable target.

The other thing is to enable the test suites, and then run them, and hopefully get them clean. At the moment they aren't, but a lot of that is because many tests are OS-specific and they don't know what Solaris is so get confused. With all the tags, I can bisect on failures and (hopefully) fix them.

Building up networks of zones on Tribblix

With OpenSolaris and derivatives such as illumos, we gained the ability to build a whole IT infrastructure in a single box, using virtualized networking (crossbow) to build the underlying network and then attaching virtualized systems (zones) atop virtualized storage (zfs).

Some of this was present in Solaris 10, but it didn't have crossbow so the networking piece was a bit tricky (although I did manage to get surprisingly far by abusing the loopback interface).

In Tribblix, I've long had the notion of a router or proxy zone, which acts as a bridge between the outside world and a local virtual subnet. For the next release I've been expanding that into something much more flexible and capable.

What did I need to put this together?

The first thing is a virtual network. You use dladm to create an etherstub. Think of that as a virtual switch you can connect network links to.

To connect that to the world, a zone is created with 2 network interfaces (vnics). One over the system interface so it can connect to the outside world, and one over the etherstub.

That special router zone is a little bit more than that. It runs NAT to allow any traffic on the internal subnet - simple NAT, nothing complicated here. In order to do that the zone has to have IPFilter installed, and the zone creation script creates the right ipnat configuration file and ensures that IPFilter is started.

You also need to have IPFilter installed in the global zone. It doesn't have to be running there, but the installation is required to create the IPFilter devices. Those IPFilter devices are then exposed to the zone, and for that to work the zone needs to use exclusive-ip networking rather than shared-ip (and would need to do so anyway for packet forwarding to work).

One thing I learnt was that you can't lock the router zone's networking down with allowed-address. The anti-spoofing protection that allowed-address gives you prevents forwarding and breaks NAT.

The router zone also has a couple of extra pieces of software installed. The first is haproxy, which is intended as an ingress controller. That's not currently used, and could be replaced by something else. The second is dnsmasq, which is used as a dhcp server to configure any zones that get connected to the subnet.

With a network segment in place, and a router zone for management, you can then create extra zones.

The way this works in Tribblix is that if you tell zap to create a zone with an IP address that is part of a private subnet, it will attach its network to the corresponding etherstub. That works fine for an exclusive-ip zone, where the vnic can be created directly over the etherstub.

For shared-ip zones it's a bit trickier. The etherstub isn't a real network device, although for some purposes (like creating a vnic) it looks like one. To allow shared-ip, I create a dedicated shared vnic over the etherstub, and the virtual addresses for shared-ip zones are associated with that vnic. For this to work, it has to be plumbed in the global zone, but doesn't need an address there. The downside to the shared-ip setup (or it might be an upside, depending on what the zone's going to be used for) is that in this configuration it doesn't get a network route; normally this would be inherited off the parent interface, but there isn't an IP configuration associated with the vnic in the global zone.

The shared-ip zone is handed its IP address. For exclusive-ip zones, the right configuration fragment is poked into dnsmasq on the router zone, so that if the zone asks via dhcp it will get the answer you configured. Generally, though, if I can directly configure the zone I will. And that's either by putting the right configuration into the files in a zone so it implements the right networking at boot, or via cloud-init. (Or, in the case of a solaris10 zone, I populate sysidcfg.)

There's actually a lot of steps here, and doing it by hand would be rather (ahem, very) tedious. So it's all automated by zap, the package and system administration tool in Tribblix. The user asks for a router zone, and all it needs to be given is the zone's name, the public IP address, and the subnet address, and all the work will be done automatically. It saves all the required details so that they can be picked up later. Likewise for a regular zone, it will do all the configuration based on the IP address you specify, with no extra input required from the user.

The whole aim here is to make building zones, and whole systems of zones, much easier and more reliable. And there's still a lot more capability to add.

Keeping python modules in check

Any operating system distribution - and Tribblix is no different - will have a bunch of packages for python modules.

And one thing about python modules is that they tend to depend on other python modules. Sometimes a lot of python modules. Not only that, the dependency will be on a specific version - or range of versions - of particular modules.

Which opens up the possibility that two different modules might require incompatible versions of a module they both depend on.

For a long time, I was a bit lax about this. Most of the time you can get away with it (often because module writers are excessively cautious about newer versions of their dependencies). But occasionally I got bitten by upgrading a module and breaking something that used it, or breaking it because a dependency hadn't been updated to match.

So now I always check that I've got all the dependencies listed in packaging with

pip3 show modulename

and every time I update a module I check the dependencies aren't broken with

pip3 check

Of course, this relies on the machine having all the (interesting) modules installed, but on my main build machine that is generally true.

If an incompatibility is picked up by pip3 check then I'll either not do the update, or update any other modules to keep in sync. If an update is impossible, I'll take a note of which modules are blockers, and wait until they get an update to unjam the process.

A case in point was that urllib3 went to version 2.x recently. At first, nothing would allow that, so I couldn't update urllib3 at all. Now we're in a situation where I have one module I use that won't allow me to update urllib3, and am starting to see a few modules requiring urllib3 to be updated, so those are held downrev for the time being.

The package dependencies I declare tend to be the explicit module dependencies (as shown by pip3 show). Occasionally I'll declare some or all of the optional dependencies in packaging, if the standard use case suggests it. And there's no obvious easy way to emulate the notion of extras in package dependencies. But that can be handled in package overlays, which is the safest way in any case.

Something else the checking can pick up is when a dependency is removed, which is something that can be easily missed.

Doing all the checking adds a little extra work up front, but should help remove one class of package breakage.

It seemed like a simple problem to fix

While a bit under the weather last week, I decided to try and fix what at first glance appears to be a simple problem:

need to ship the manpage with exa

Now, exa is a modern file lister, and the package on Tribblix doesn't ship a man page. The reason for that, it turns out, is that there isn't a man page in the source, but you can generate one.

To build the man page requires pandoc. OK, so how to get pandoc, which wasn't available on Tribblix? It's written in Haskell, and I did have a Haskell package.

Only my version of Haskell was a bit old, and wouldn't build pandoc. The build complains that it's too old and unsupported. You can't even build an old version of pandoc, which is a little peculiar.

Off to upgrade Haskell then. You need Haskell to build Haskell, and it has some specific requirements about precisely which versions of Haskell work. I wanted to get to 9.4, which is the last version of Haskell that builds using make (and I'll leave Hadrian for another day). You can't build Haskell 9.4 with 9.2 which it claims to be too new, you have to go back to 9.0.

Fortunately we do have some bootstrap kits for illumos available, so I pulled 9.0 from there, successfully built Haskell, then cabal, and finally pandoc.

Back to exa. At which point you notice that it's been deprecated and replaced by eza. (This is a snag with modern point tools. They can disappear on a whim.)

So let's build eza. At which point I find that the MSRV (Minimum Supported Rust Version) has been bumped to 1.70, and I only had 1.69. Another update required. Rust is actually quite simple to package, you can just download the stable version and package it.

After all this, exa still doesn't have a man page, because it's deprecated (if you run man exa you get something completely different from X.Org). But I did manage to upgrade Haskell and Cabal, I managed to package pandoc, I updated rust, and I added a replacement utility - eza - which does now come with a man page.

When zfs was young

On the Solaris 10 Platinum Beta program, one of the most exciting promised features was ZFS, the new file system.

I was especially interested, given that I was in a data-heavy position at the time. The limits of UFS were painful, we had datasets into several terabytes already - and even the multiterabyte file system support that got added was actually pretty useless because the inode density was so low. We tried QFS and SAM-QFS, and they were pretty appalling too.

ZFS was promised, and didn't arrive. In fact, there were about 4 of us on the beta program who saw the original zfs implementation, and it was quite different from what we have now. What eventually landed as zfs in Solaris was a complete rewrite. The beta itself was interesting - we were sent the driver, 3 binaries, and a 3-line cheatsheet, and that was it. There was a fundamental philosophy here that the whole thing was supposed to be so easy to use and sufficiently obvious that it didn't need a manual, and that was actually true. (It's gotten rather more complex since, to be fair.)

The original version was a bit different in terms of implementation than what you're used to, but not that much. The most obvious change was that originally there wasn't a top-level file system for a pool. You created a pool, and then created your file systems. I'm still not sure which is the correct choice. And there was a separate zacl program to handle the ACLs, which were rather different.

In fact, ACLs have been a nightmare of bad implementations throughout their history on Solaris. I already had previous here, having got the POSIX draft ACL implementation reworked for UFS. The original zfs implementation had default aka inheritable ACLs applied to existing objects in a directory. (If you don't immediately realise how bad that is, think of what this allows you to do with hard links to files.) The ACL implementations have continued to be problematic - consider that zfs allows 5 settings for the aclinherit property as evidence that we're glittering a turd at this point.

Eventually we did get zfs shipped in a Solaris 10 update, and it's been continually developed since then. The openzfs project has given the file system an independent existence, it's now in FreeBSD, you can run it (and it runs well) on Linux, and in other OS variations too.

One of the original claims was that zfs was infinitely scalable. I remember it being suggested that you could create a separate zfs file system for each user. I had to try this, so got together a test system (an Ultra 2 with an A1000 disk array) and started creating file systems. Sure, it got into several thousand without any difficulty, but that's not infinite - think universities or research labs and you can easily have 10,000 or 100,000 users, we had well over 20,000. And it fell apart at that scale. That's before each is an NFS share, too. So that idea didn't fly.

Overall, though, zfs was a step change. The fact that you had a file system that was flexible and easily managed was totally new. The fact that a file system actually returned correct data rather than randomly hoping for the best was years ahead of anything else. Having snapshots that allowed users to recover from accidentally deleted files without waiting days for a backup to be restored dramatically improved productivity. It's win after win, and I can't imagine using anything else for storing data.

Is zfs perfect? Of course not, and to my mind one of the most shocking things is that nothing else has even bothered to try and come close.

There are a couple of weaknesses with zfs (or related to zfs, if I put it more accurately). One is that it's still a single-node file system. While we have distributed storage, we still haven't really matured that into a distributed file system. The second is that while zfs has dragged storage into the 21st century, allowing much more sophisticated and scalable management of data, there hasn't been a corresponding improvement in backup, which is still stuck firmly in the 1980s.