NFS broken in Sequoia 15.6

It would be better to use SMB. NFS hasn't been supported on the Mac in many years.

The fundamental problem is permissions. NFS is designed to run as the root user. But on modern macOS, root is one of the least powerful user accounts.

elisatems wrote:

But what changed in the latest OS update? Why does this not work anymore?

No clue. Last time I used NFS on any system was 2014. I'm not surprised it doesn't work. I'm only surprised that it stopped working for you recently. I would have expected a post like this in 2018 or 2019 maybe.

I fired it up to test and I couldn't get an external volume to share via NFS. An internal volume worked fine. I didn't try very hard. There are dozens of things that could potentially be breaking it. And it might simply not be possible at all.

You can give up now, switch to SMB, and have it working before lunch. Or keep trying for a few more days and give up then. If you want to prove me wrong, please make sure to post a detailed explanation of how you did it.

elisatems wrote:

I have no interest in proving anyone wrong

I'm somewhat sincere about that. I would really like to know if this is fixable. I just don't think it's a worthwhile exercise.

I'm just not that familiar with SMB - I only remember it as a protocol for sharing volumes between Windows-based and Unix or Linux systems via Samba. I guess I'll have to do some research to learn how to do SMB between Linux and MacOS.

SMB's not difficult. It supports modern file system permissions, which is the big issue. To this day, Apple still officially supports Time Machine over SMB. So if Apple's SMB can handle something that intense, it should be pretty reliable. (Full disclosure: I haven't tested Time Machine over SMB in a long time. And the last time I did a couple of years ago, an Apple bug disabled it for the better part of a year. That's the level of support you get for Apple's "full support" - it works, and if it doesn't work, it might work again in a few months.)

But I *am* surprised that you couldn't get it to work at all.

As I said, I didn't try very hard.

The volume I've been sharing is an external volume and it's worked fine until 15.6. It still works, initially, but becomes unreachable within less than an hour typically.

Perhaps it's not an NFS problem at all. It could be a networking problem. Most of those breaking network changes were in the initial Sequoia release, but you can always double-check things like MAC randomization, energy-efficient ethernet, etc. If you're someone who uses NFS, you might be using other funky network settings. High risk of random breakage with those.

elisatems wrote:

I don't have any unusual options in my NFS server settings on the Mac - no added switches, just the defaults. And my /etc/exports is exactly as posted in the OP. My local network is controlled by an Arris cable modem - but the settings you suggested to check are not options the modem's admin web page even displays. I did check the basic network setup and noticed that the starting address for Wi-Fi had defaulted to a value that conflicted with both the Linux box and the Mac (both connect via ethernet), so I fixed that - but none of my devices/appliances that use Wi-Fi that I'm aware of had been assigned conflicting addresses, and anyway an IP address conflict would affect more than just NFS.

I'll look further into SMB - for now, I've removed the backup share from /etc/fstab and disabled the cron job. I gather from a quick web search that SMB is supported in the MacOS kernel, and the mount command on the Linux box does support -t smbfs, so hopefully the switch will be painless. Thank you for your input.

I don't know if SMB is going to help.

You need to re-evaluate how your network is configured. I don't know what else to tell you. I could write a whole page worth of questions. I need, I just deleted a whole page worth of questions.

My suggestion is to look at the low-level network settings on the NFS server. It sounds like it's doing some kind of MAC rotation or randomization. That is the default. And Apple applied that new default when Sequoia was released. I don't know why it would suddenly start affecting you a year later, but that's sure what it sounds like.

And then there's a whole world of things that I just assume you aren't doing, mostly involving 3rd party "security" or "network" software. People who usually swear they aren't using any of that typically are running the worst of the worst.

AFAICT, NFS is all but dead at Apple.

SMB would be the most expedient approach and the next thing to test here.

You can struggle with the current setup, or can try using what Apple spends more time with, SMB.

As for network limitations, if your ISP modem supports bridged mode, and various providers do, then you can use your own network gear. That path requires more effort, more costs, more knowledge, and more control. And likely unnecessary, if the Apple SMB server works, where the NFS server (may be) failing.

But if neither NFS nor SMB works here, I’d then be looking at the Linux box, and at the local network.

The network vendor I usually work with offers gear that supports redundant ISP links and redundant gateway access (transparently), but the simplest expedient for local uptime requirements regardless of vendor is to buy two and swap.

elisatems wrote:

You're making a lot of assumptions about what I'm running there.

I'm doing exactly the opposite - expressing my ignorance of how your network is configured.

Why don't you ask questions instead of assuming what I'm doing or not doing?

As I said, I did, but then I deleted them as I was afraid it would be overwhelming. Usually, if I ask someone 3 questions, they'll pick one at random to answer. That's always awkward. Can you imagine how it is when I ask 20?

First, just to clarify: my NFS server settings are the defaults on MacOS, so it's possible that something did change there as I've never made any customizations on the NFS config files, other than my /etc/exports.

As I said, I don't think it's an NFS problem. You are able to connect initially but then the connection goes stale. That strongly indicates that some portion of the link has changed and the other side didn't know about that. There are multiple places in Sequoia's low-level networking settings that will do precisely that.

It's possible that Apple's SMB implementation will handle this situation better. You can test that in about 2 minutes.

It's also possible that some low-level networking default (not NFS) has changed and you can simply change it back. You can test that in about 2 days.

Also: there is no 3rd party security or networking software running on my network, other than on the Arris modem itself. I use the modem's firewall with all external ports blocked. This is all determined by my ISP - I do not have a lot of choice as to networking hardware.

You see? This is what I mean about the twenty questions. You were very specific about 3rd party security or networking software. OK. That's good. But what about built-in software? One of the things that changed in Sequoia was the built-in, useless application firewall. Before Sequoia, it never did anything anyway, and was riddled with bugs, but at least it was fairly benign. But there are new bugs in Sequoia that push the application firewall from merely useless, to a harmful detriment.

I can go on for pages and pages with diagnostic suggestions. But there's nothing I can say that would be more useful than you poking around with the actual devices for a few minutes. I'm just saying that I doubt the problem is anywhere with NFS. I think the problem is a low-level networking change that you can simply undo. If not that, I think it would probably work fine with SMB making no changes. Either way, it would take me longer to type all that than for you to just check and try a few things. And if I'm wrong and the problem is intimately related to Apple's NFS implementation, then it's a total lost cause. SMB is your only option in that case.

elisatems wrote:

Do you have any links to documentation, or even suggestions of which settings to check?

The first place to look is System Settings > Network. I don't know how your system is configured, so some things might not apply. One new setting in Sequoia was Private WiFi Address. As soon as I saw that I knew it would be trouble. I changed the new default to "fixed" so it would behave as it did before. This is the most likely candidate.

There is also a "low power mode" for WiFi. Both Ethernet and WiFi also have a setting for Limit IP Address Tracking. I don't know if these settings are related to the problem you're experiencing.

I don't know much about Ethernet since it's been many years since I've had a Mac with built-in ethernet. If you're using a USB ethernet dongle, all bets are off. You're on your own there. That could break things for multiple reasons, including for the simple fact that you (might?) have multiple interfaces.

If you're referring to the built-in firewall in MacOS that's configurable via System Settings -> Network, it's disabled.

That's good! All it ever did was protect you from that modem and Linux server on your local network.

Understood. Unfortunately since I've never played with the low-level network settings before, I would have no idea what has changed. Probably best if I just try SMB without making any changes to the low-level settings and see if the shared filesystem will stay reachable.

Also try a local export and see if that behaves the same way. What's most confusing to me is the fact that your setup is working at all. It's mainly the crazy Mac permissions that cause problems. Somehow you seem to have avoided that and are dealing with some link-layer problem.

It's possible that SMB will somehow avoid that link-layer problem. That's something you could test really easily. But it would still be interesting to know what precisely is causing your problem. It's all a question of how much time you want to put into debugging it. Or just switch to SMB and maybe get lucky.