Permission denied when SSHing into Ubuntu Virtual Machine

I have a VirtualBox machine running Ubuntu 18.04.2. I have installed OpenSSH on it.

In the Settings of the Virtual Machine I have set up this port forwarding rule:

Protocol: TCP

Host IP: 127.0.0.1

Host Port: 2222

Guest IP: 10.0.2.15

Guest Port: 22

The SSH command I run in my local terminal is:

ssh myname@127.0.0.1 -p2222 

It then asks me for the password, which I enter, and I get this error:

Permission denied, please try again.

The username and password are the ones I created when setting up Ubuntu.

Slow upload speed on machine running Ubuntu Server 18.04

I’m currently running Ubuntu Server 18.04 on a home server build to act as a Plex server, among other things. I have it connected via ethernet (with a 5-port switch between it and the router), and get download speeds consistently in the 750-900 MBit/s range when running speedtest-cli, which is expected. However, the upload speed has never gone above 5 MBit/s, despite every other machine in the house getting speeds around 300-400 or more when performing speedtests.

How can I diagnose what might be causing these slow upload speeds? I’m unsure what might be causing the issue if other devices are having no trouble on the same network, including another computer that is connected to the same 5-port switch. I tried basic things like resetting the router and swapping cables and ports on the switch but that did not change anything.

I have a vbox extension virtual machine instead of vdi. How should I resize storage of vbox?

I’m trying to install Ubuntu on the virtual box using USB. My primary OS is also Ubuntu. When I’m booting, it’s giving me this problem: screenshot

So, I’m trying to find a way to resize the storage. I came across this command: VBoxManage modifyhd YOUR_HARD_DISK.vdi --resize SIZE_IN_MB , but this only works if the image extension is vdi.

In my system, under Virtual box image folder, it’s shows Ubuntu.vbox instead of Ubuntu.vdi.

I upgraded from Ubuntu 12.02 to 14.04 but when I log in from my Oracle Virtual Machine it boots to the old version (12.02)

So my PC has 2 hard drives. One for Windows and one for Linux. By default it boots to Windows and if I want to run Linux I simply hold F2 upon start up to enter the Bios and boot into Linux from there. Originally I was using Ubuntu 12.02 but upgraded to 14.04. I was also using Oracle VM on my Windows OS to log into Ubuntu via virtual machine. Since I’ve upgraded my Ubuntu version to 14.04, when I attempt to log into Linux via virtual machine, it boots to the Ubuntu 12.02 version, so I cant access any of my files, programs, etc…that exist on my 14.04 version. I would like to be able to access Ubuntu 14.04 from my VM on Windows instead of booting Linux from the Bios every time, but it’s currently pointless as the VM boots to the older version of Ubuntu, which has nothing on it.

Ubuntu failed to start servers while turning on the machine

When I tried to turned on my ubuntu machine. It is not able to start the servers and it halt on this screen itself. Here I have attached my screen below.

Earlier, I got a notification regards – Running out of space and the Ubuntu notified me to Empting the Trash.

Does the issue is occuring because of Empted the Trash ubuntufailedtostartservice

How can the VC-dimension of Turing machine be finite?

The VC-dimension of a hypothesis class $ \mathcal{H}$ is defined to be the size of the maximal set $ C$ such that $ \mathcal{H}$ cannot shutter. This paper shows that the VC-dimension of the set of all Turing Machines with $ n$ states is $ \Theta(n \log n)$ .

However, suppose that we take the set of all such Turing machines, for $ n$ sufficiently large so that the universal Turing machine is a member of $ \mathcal{H}$ . The result states that there exists a set $ C$ (wlog, $ C \subset \{0,1\}^*$ ) of size, say, $ n^2$ , such that $ \mathcal{H}$ cannot shatter. To my understanding, it means that there is no member of $ \mathcal{H}$ which can compute the function $ $ f(x) = \begin{cases} 1 \text{ if } x \in C(1) \ 0 \text{ else} \end{cases} $ $ Where $ C(1)$ are the points with label “1”.

But $ C$ is finite hence $ f$ is clearly computable, thus there is some Turing machine $ M_C$ which computes it, therefore $ M_C$ can be simulated by the universal Turing machine, which is in $ \mathcal{H}$ , and this is a contradiction. Where is the problem with this argument?

If the human brain is turing machine then how is it able to ascertain that certain problems are undecidable?

I recently read about the idea that the human brain might be a turing machine (or turing complete). If that is true then how is the brain able to reason that a certain problem is undecidable for e.g. the the liar paradox. I assume that a turing machine will nor be able to reason that the liar paradox statement is a logical paradox with no decidable answer and will be stuck forever.

can’t remove Postman from Ubuntu 16.04 machine

Somehow I have ended up with one version of Postman installed on /usr/opt as a folder and on /usr/bin and /usr/lib.

I tried to clean the mess and remove postman (all of it) especially the one stacked in usr/bin, which is (from what I have read) not a proper place for it. I failed using all conventional methods: apt remove –purge (=>unable to locate), synaptic Ubuntu Software Center.

But Postman is there and it works. What is going on?