Figured I’d expand on something Alex said in response to you.
Client side should not hash the password which I am fairly sure would allow pass-the-hash, but don’t quote me on that.
Basically hashing it on the client doesn’t solve the problem it just shifts it a bit. Instead of needing to capture and then send the plaintext password to the server. An attacker would simply need to capture and send the hash as generated by the client to the server. In both cases an attacker with access to the plain communication between client and server would have all the information necessary.
Basically if you hash it on the client-side, you’ve just made the hash the password that needs to be protected as an attacker only needs to “pass the hash” to the server.
That said you are raising a legitimate concern and its a great question that shows you’re starting to think about the issues at hand. Because, you’re right. When we send the password in plaintext at the application layer we are simply trusting that the communication channel is secure, and that is not a safe assumption.
There is a bit of a rabbit hole regarding authentication schemes you can dive into and there is a scheme that adds a bit more onto the simple idea of just hashing the password on the client-side. Basically, the server provides a nonce (a one-time use value) to the client. The client hashes their password with this nonce included and sends the resultant hash back to the server to be validated. It kinda solves the issue of someone being able to read the communication as the hash being sent over the wire is only useful in response to that specific nonce for that specific user.
The trade-off on this is that in-order for the server to be able to validate the response from the client, the server must have access to that same key-data the client hashed with the nonce, AKA passwords needs to be stored in a recoverable way. You increase security against a compromised communication channel, but also increased the damage that an attacker could do if they could leak the database.
Going further down the rabbit hole, there is Salted Challenge-Response Authentication which takes a step towards alleviating this by storing a salted and hashed version of the password. And then providing the client the nonce as usual along with the salt and other information needed for the client to reproduce the version of the hash the server is storing. This does mean passwords are not in “plaintext” but it has in effect made the hashed version the password that should be protected. Anyone who compromises the database still has all the information necessary to generate the response for any nonce. They just couldn’t try for password reuse stuff like one could if it was actually recoverable.
Ultimately, this comes down to what is the bigger threat. You can (somewhat) secure against a compromised communication channel (which is generally a targeted attack against only one user at a time), but it means that some server side vulnerabilities will be able to compromise every user account. In general, for web-apps I think you’re better off hardening the server-side and having mitigations like 2FA around sensitive actions to limit the damage just compromising the password could do.
Also, if you really wanted to be more secure against communication channel issues, public key cryptography is a better tool for that, but has generally not be well supported for web-apps.
Namespaces basically are a sort of kernel enforced isolation. A processes enters a namespace and to that process it might be root on its own machine. Behind the scenes the kernel is kinda translating everything it does so into its own little sandboxed area instead of the root system. But inside that namespaces it legitimately thinks it is the root user and can exercise most of the functional that is only exposed to privileged users. (f course the kernel limits what it can do to only being inside it’s own little space so that alone isn’t an issue.
When it comes to hardening, the namespaces are not inherently insecure. The difference is in the “attack surface” an unprivileged user has access to through them.
A simple example of this is mounting a filesystem. Now the user won’t be able to like remount a privileged filesystem or something it’ll be isolated. But let’s say there is a vulnerability in the exact filesystem code in the kernel, your server doesn’t mount any exfat drives and you disallow automounting of anything for hardening. So even if the issue exists an attacker couldn’t exploit it because the exfat code isn’t reachable as normal user. With a user namespaces though a user becomes root of their own little area so they can actually ask the kernel to mount something inside their namespace. So now with a namespace an attacker can get access to exploit their theoretical exfat filesystem vulnerability.
tl;dr the problem with having namespaces on is it allows unprivileged users access to a lot more “potentially” vulnerable code that could be exploitable.