anon2963

joined 7 months ago
 

I am setting up a Linux server (probably will be NixOS) where my VM disk files will be stored on top of an NTFS partition. (Yes I know NTFS sucks but it has to be this way.)

I am asking which guest filesystem will have the best performance for a very mixed workload. If I had access to the extra features of BTRFS or ZFS I would use them but I have no idea how CoW interacts with NTFS; that is why I am asking here.

Also I would like some NTFS performance tuning pointers.

[–] anon2963@infosec.pub 3 points 2 months ago (1 children)

Usually these drives will be mounted on Linux. But occasionally they will be mounted on Windows 10 where I do not have admin or developer mode access, so I cannot depend on symlinks.

 

This is more of a system config question than a programming one, but I think this community is the best one to ask about anything Git-related.

Anyway, I am setting up a new project with hardware that has 2 physical drives. The "main" drive will usually be mounted and have 10-20 config files on it, maybe 50-100 LOC each. The "secondary" drive will be mounted only occasionally, and will have 1 small config file on it, literally 2 or 3 LOC. When mounted, this file will be located in a specific directory close to the other config files.

I would like to manage all of these files using git, ideally with a single repo, as they are all part of the same project. However, as the second drive (and thus the config file on it) will sporadically appear and disappear, Git will be confused and constantly log me adding and deleting the file.

Right now I think the most realistic solution is to make a repo for each drive and make the secondary drive a submodule of the main. But I feel like it is awkward to make a whole repo for such a simple file.

What would you do in this situation, and what is best practice? Is there a way to make this one repo?

[–] anon2963@infosec.pub 2 points 3 months ago

Thanks for the wonderful info. I think I will go with the iStorage datAshur PRO+C because it has the best speeds out of all of them. It is slightly more involved to activate read-only mode than a simple switch, but it should be negligible compared to the time to boot the system and other overhead.

There is no way for me to verify how the write-protect works with this drive, but that is true for all of them, so I have to trust one. However, this company seems very competent. And importantly there are many 3rd party reviews of this and similar iStorage products. Also the firmware is supposedly signed so it should be immune to badUSB. But you do make the point that there is no way to be sure.

I plan to use root on LUKS anyway (I want persistent storage), so I can keep / encrypted and checksum my /boot every boot to search for anomalies. Once LUKS is decrypted, theoretically malware could get embedded in there, but I feel like it would be unlikely for malware to infect one partition and not the other.

I wonder if there is a way to setup a "honeypot" partition which holds no useful data but exhibits traits that are appealing for malwares to embed themselves in. It would be checksummed regularly while the system was running and alert me if anything changed.

That open source flash drive looks awesome, and I will keep my eye on it, maybe I would consider it if my threat model was tougher.

 

I am looking for a fast USB drive which has a physical write-protect enable switch on it. I would also want a BadUSB-resistant USB controller. I want this for 2 reasons:

  • So I can diagnose issues on machines where the problem may or may not be malware. This way, I can plug it into several machines without risking spreading malware.

  • So I can carry around a TailsOS drive wherever I go, and use it on public computers and friend's computers without risk of infection.

So far, I have only found one company making these things, Kanguru. There are almost no reviews of their products by reputable sources, at least not for their write-protecting drives.

Their BadUSB firmware detection module is NIST certified, which is great (given that you trust proprietary cryptography modules at all), but no certs for the main storage write protection. Also Kanguru products are very overpriced.

And no I am not using SD cards, their write protect implementation is software-based and they are too slow for me.

I am specifically looking at the Kanguru FlashTrust . My questions are:

  • Has anyone used Kanguru products and how was your experience?

  • Are there other companies that make decent quality drives with hardware write-protect switches? (Ideally ones that have FOSS firmware and are third-party tested, but I will take anything).

  • Are there any companies that make USB writeblockers which are small enough to fit in a wallet and <$50? (Example of one that is too big). That way I can use a standard, cheaper USB drive.

Oh how I wish Nitrokey made these!

 

My question is whether it is good practice to include a unique wrapper phrase for custom commands and aliases.

For example, lets say I use the following command frequently:

apt update && apt upgrade -y && flatpak update

I want to save time by shortening this command. I want to alias it to the following command:

update

And lets say I also make up a command that calls a bash script to scrub all of of my zfs and btrfs pools:

scrub

Lets say I add 100 other aliases. Maybe I am overthinking it, but I feel there should be some easy way to distinguish these from native Unix commands. I feel there should be some abstraction layer.

My question is whether converting these commands into arguments behind a wrapper command is worth it.

For example, lets say my initials are "RK". The above commands would become:

rk update rk scrub

Then I could even create the following to list all of my subcommands and their uses:

rk --help

I would have no custom commands that exist outside of rk, so I add to total of one executable to my system.

I feel like this is the "cleaner" approach, but what do you think? Is this an antipattern? Is is just extra work?

 

I am planning to build a multipurpose home server. It will be a NAS, virtualization host, and have the typical selfhosted services. I want all of these services to have high uptime and be protected from power surges/balckouts, so I will put my server on a UPS.

I also want to run an LLM server on this machine, so I plan to add one or more GPUs and pass them through to a VM. I do not care about high uptime on the LLM server. However, this of course means that I will need a more powerful UPS, which I do not have the space for.

My plan is to get a second power supply to power only the GPUs. I do not want to put this PSU on the UPS. I will turn on the second PSU via an Add2PSU.

In the event of a blackout, this means that the base system will get full power and the GPUs will get power via the PCIe slot, but they will lose the power from the dedicated power plug.

Obviously this will slow down or kill the LLM server, but will this have an effect on the rest of the system?

[–] anon2963@infosec.pub 2 points 5 months ago (1 children)

In the past I have used Proxmox with ZFS raid on a basic mini PC. With ZFS raid it syncs everything except /boot. Proxmox has a tool called "proxmox-boot-tool-refresh" which will syncs /boot between drives. ZFS kernel module can be loaded in the initramfs so it will boot fine, even if missing a drive.

For this project I do not plan to use ZFS, but AFAIK software raid is now standard. Here is a popular video from Level1Techs talking about the flaws of hardware RAID: https://youtu.be/l55GfAwa8RI

 

I have an 11th gen Framework mainboard which I would like to repurpose as a server. Unfortunately, (unless I do some super janky stuff) I can only connect 1 drive to it over M.2 and any additional ones must be over USB.

I am thinking of just using some portable hard drives and plugging them in over USB. I plan to RAID1 them and use them as boot drives and data storage, and use the M.2 slot for something unrelated.

In your experiences, is USB reliable enough nowadays to run a RAID array for a server like this? If it is, does it depend on the specific drive used?

 

I am currently learning to be a sysadmin and I have no software development skills. I love FOSS very much and want to contribute to several projects, including non-networked ones.

How can I do this with my skillset? I have a very small (16GB RAM) server that I could offer to these projects as a build server or web host. IDK what else I could do.

 

I am wondering what the standard tool is for sending and receiving SMS and MMS on a device that does not have a SIM card in it.

Is there some tool that can do it natively? Is there a specific carrier that is commonly used for this? Is there some sort of selfhosted service that bridges it to email, and if so do I need to put a SIM card in my server?

Bonus points if I can do it within Emacs.

[–] anon2963@infosec.pub 2 points 5 months ago (1 children)

Thank you for the detailed reply. You seem very knowledgeable. I will implement your suggestions as I redesign my network.

[–] anon2963@infosec.pub 2 points 5 months ago

Thanks. Some of these entries maybe (20%) have IOMMU groups listed under "lspci_all". But it is extremely awkward to search through. So maybe I will put a feature request in the forum to make IOMMU more searchable. But this is still likely the largest database of IOMMU groupings on the web, even if it is not easily searchable.

[–] anon2963@infosec.pub 1 points 5 months ago

Thanks but these are only lists of CPUs and motherboards that support IOMMU, not the IOMMU groups. For me (and many others) the groupings are just as important as whether there is support at all.

The groupings are defined by the motherboard. In my experience, all motherboards that support IOMMU will put at least 1 PCIe slot in its own own group, which is good for Graphics Card passthrough. However, the grouping of other stuff like SATA controllers and NICs varies wildly between board, and that is what I am interested in.

 

I am looking to buy a new mini PC home server and I want to be able to pass through my iGPU and NIC to different VMs. Where can I find a well-maintained database of IOMMU groups so that I can pick a good match for my needs?

There exists iommu.info but that barely has any entries.

[–] anon2963@infosec.pub 2 points 5 months ago (3 children)

Thank you, that is a very good point, I never thought of that. Just to confirm, best standard practice is for every connection, even as simple as a Nextcloud server accessing an NFS server, to go through the firewall?

Then I could just have one interface per host but use Proxmox host ID as the VLAN so they are all unique. Then, I would make a trunk on the guest OPNsense VM. In that way it is a router on a stick.

I was a bit hesitant to do firewall rules based off of IP addresses, as a compromised host could change its IP address. However, if each host is on its own VLAN, then I could add a firewall rule to only allow through the 1 "legitimate" IP per VLAN. The rules per subnet would still work though.

I feel like I may have to allow a couple CT/VMs to communicate without going through the firewall simply for performance reasons. Has that ever been a concern for you? None of the routing or switching would be hardware accelerated.

[–] anon2963@infosec.pub 2 points 6 months ago

Search eBay for used gaming laptops. Comes with a built in UPS.

 

I am currently setting up a Proxmox box that has the usual selfhosted stuff (Nextcloud, Jellyfin, etc) and I want all of these services in different containers/VMs. I am planning to start sharing this with family/friends who are not tech savvy, so I want excellent security.

I was thinking of restricting certain services to certain VLANs, and only plugging those VLANs into the CT/VMs that need them.

Currently, each CT/VM has a network interface (for example eth0) which gives them internet access (for updates and whatnot) and an interface that I use for SSH and management (for example eth1). These interfaces are both on different VLANs and I must use Wireguard to get onto the management network.

I am thinking of adding another interface just for “consumption” which my users would get onto via a separate Wireguard server, and they would use this to actually use the services.

I could also add another network just to connect to an internal NFS server to share files between CT/VMs, and this would have its own VLAN and require an additional interface per host that connects to it.

I have lots of other ideas for networks which would require additional interfaces per CT/VM that uses them.

From my experience, using a “VLAN-Aware” bridge and assigning VLANs per interface via the GUI is best practice. However, Proxmox does not support multiple VLANs per interface using this method.

I have an IPv6-only network, so I could theoretically assign multiple IPs per interface. Then I would use Linux VLANs from within the guest OS. However, this is a huge pain and I do not want to do this. And it is less secure because a compromised VM/CT could change its VLAN tag itself.

I am asking if adding many virtual interfaces per CT/VM is good practice, or if there is a better way to separate internal networks. Or maybe I should rethink the whole thing and not use one network per use-case.

I am especially curious about performance impacts of multiple interfaces.

[–] anon2963@infosec.pub 0 points 7 months ago

Thanks for the wise words. However I have some questions:

If you’re worried about someone malicious having access to your network connection, ssh is going to do a DNS lookup to map the hostname to an IP for the client.

Are you sure that this is true for Tor? .onion addresses never resolve to an IP address, even for the end user client. If I was on an untrusted network, both for the client and the server, the attacker could find out that I was using Tor, but not know literally anything more than that.

And attackers have aimed to exploit things like buffer overflows in IDSes before – this is a real thing.

I would expect an IDS to be an order of magnitude larger attack surface than Wireguard, and significantly less tested. Although I could also say that about SSH, and we had the recent backdoor. However, I think it is a lot more likely that a bug will cause a security method to be ineffective than actively turn it in to a method for exfiltration or remote access though. For example, with the recent SSH backdoor, if those servers had protected SSH behind Wireguard then they would have been safe even if SSH was compromised.

 

cross-posted from: https://infosec.pub/post/10908807

TLDR:

If I use SSH as a Tor hidden service and do not share the public hostname of that service, do I need any more hardening?

Full Post:

I am planning to setup a clearnet service on a server where my normal "in bound" management will be over SSH tunneled through Wireguard. I also want "out of bound" management in case the incoming ports I am using get blocked and I cannot access my Wireguard tunnel. This is selfhosted on a home network.

I was thinking that I could have an SSH bastion host as a virtual machine, which will expose SSH as a a hidden service. I would SSH into this VM over Tor and then proxy SSH into the host OS from there. As I would only be using this rarely as a backup connection, I do not care about speed or convenience of connecting to it, only that it is always available and secure. Also, I would treat the public hostname like any other secret, as only I need access to it.

Other than setting up secure configs for SSH and Tor themselves, is it worth doing other hardening like running Wireguard over Tor? I know that extra layers of security can't hurt, but I want this backup connection to be as reliable as possible so I want to avoid unneeded complexity.

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