virtual machine: How do virtual machines and GCs handle objects that wrap around active resources but cannot be accessed from user code?

I am building a C interpreter for a simple programming language.

The interpreter is equipped with a built-in garbage collector. The GC simply marks all the objects that are linked from some root (the call stack, the evaluation stack, the loaded modules, etc.) and collects the rest.

Now I am writing a DLL extension for the interpreter. The DLL is "wrapping" another C graphics library (SDL). This library creates objects that represent operating system resources, such as viewports. So now I need to think about how the interpreter and the GC integrate with the "outside world" correctly.

In the current situation, one could write the following code in my language and it will work fine:

import graphics
window = graphics.new_window()
# ... all the rest

However, I suppose the following code will cause problems:

import graphics

Since the result of new_window() it is not stored anywhere, at some point the GC will collect the Window object. When picked up, the Window The object will return native resources to the operating system as part of its deallocate implementation that is being called by the GC.

I'm not sure if this is reasonable behavior for a programming language. On the one hand, if we lose the reference to the window, there is little point in filtering it.

On the other hand, if I remember correctly, in Java (and I suppose that we can find equivalent examples in most languages), it is common and legal to write code like the following (Java psuedo):

public void makeWindow() {
    new JFrame();

This would create a GUI window that will appear on the screen and remain visible. And as you can see, the JFrame The object is not saved anywhere. Still, the GC won't collect it (or at least it doesn't collect the OS resource JFrame probably wraps around).

What is the standard way to implement this in a VM language?

The only approach I can think of right now is to have objects that wrap native resources no release these resources when claimed by the GC. The only way to free these resources would be with an explicit call in the user code to a dispose Method on the object. What approach is standard in VM deployments?

privacy: someone said they accessed my router using the default password

A recent guest at my home who once worked for Cox communications said my router and all my neighbors were hacked as well. He said it was because we didn't change the original password. Apparently it was done using a cell phone. Is this possible? And if so, do you now have all our information? So should we change everything? He said he could even access his security cameras and cameras inside the devices so he could see inside.

ubuntu: server can be accessed externally, but not internally

I am running a pufferpanel server (ubuntu), and it uses a daemon and accesses it through its external IP. On my pc, I can do curl and returing works fine: {"success":true,"msg":"pufferd is running"}. the problem is when the server running pufferpanel tries to use its own port using its external IP, it doesn't work. Curl's error is curl: (7) Failed to connect to port 5656: Connection refused
IpTable looks like:

11 5 256 -A PREROUTING -i vmbr0 -p tcp -m tcp --dport 5656 -j DNAT --to-destination local.IP:5656

Windows Server 2016 – Cannot be accessed through RDP – Cannot contact local Security Authority

I recently set up Windows Server 2016 as VM on VMWare but I can't RDP on the server. I got the following error:

Authentication failed. The local security authority
He cannot be contacted. Remote computer (myserver) This could be due to
an expired password …

This computer is going to be a standalone web server and is not a domain controller. I have enabled remote connections through:

  • In the Remote section of System Properties, Enabled Allow remote connection to computer and uncheck "Allow connections only from computers running Remote Desktop with network level" Authentication (recommended) "

What am i missing?

openjdk: java.lang error cannot be accessed in netbeans 10.0 linux mint 19.2

I have NetBeans 10.0 and OpenJDK 11 installed and when I check the Java version using ~$ javac -version I get javac 11.0.6 and also when registering in netbeans using Help -> About show this:

Product version: Apache NetBeans IDE 10.0 (build 20190203-debian-10.0)
Updates: NetBeans IDE is updated to NetBeans version 8.2 Patch 2
Java: 11.0.6; OpenJDK 64-Bit Server VM 11.0.6 + 10-post-Ubuntu-1ubuntu118.04.1
Runtime: OpenJDK Runtime Environment 11.0.6 + 10-post-Ubuntu-1ubuntu118.04.1
System: Linux version 4.15.0-88-generic that runs on amd64; UTF-8; en_US (nb)
User Directory: /home/main/.netbeans/10.0
Cache directory: /home/main/.cache/netbeans/10.0

I have no idea what the problem is, since I tried so many solutions here and on other websites and I'm still getting the error. please help because I need an IDE for university assignments.

seo – Google Analytics: How to find the URLs accessed through organic traffic?

I am trying to analyze traffic through organic searches to determine which URLs are the most "popular" through search engines. And I would like to find those URLs.

In my Google Analytics account, I made the following selection:

Behavior> Site content> All pages> [I selected a specific period of time]> Add segment> Organic traffic, and then sort the URLs by "Entries". I understand that visitors entered my website through those URLs.

Is this selection correct?

Links: Local IIS can be accessed in Windows 10 using and localhost, but not through its IP

I have a notebook with Windows 10.

I have installed IIS, then I have tried to navigate, using a browser in the same notebook, to URL, it shows the default website. Then, I used localhost, and the same shows the default website. However, I used your IP, and the site is delayed for a while and then displays the message:

This site cannot be accessed

IP takes too long to respond.


(I'm sorry if the above text is not accurate like the messages in the English version of Windows. I have the Spanish version)

The default website links are set to "all assigned IP addresses". I tried to explicitly set that combo box on your IP, but the same problem occurs.

How can I solve it?

Thank you

Only the home server can be accessed from the local IP

I configured my home server with Centos 7 and I generally use the virtualmin control panel to control the server, I am currently testing my server with the vesta panel … I am not an encoder, however, I have few problems and I cannot find a solution for it anywhere,
My server is running and my test website only works on my local static IP, that is, when I enter my local static IP, I can access my website, but when I enter the domain of my website I cannot access. I do not know how to let my server use my public static IP (I have one) and how to point it to my domain name, I have already configured the name server in my domain registration company and performed port forwarding for the local static IP in the that my website works and there is already a record for public static IP … please, advice

From an SEO perspective, can you redirect from an old site that the new site cannot be accessed?

My client has an old site that cannot be accessed. It was registered by a company that is out of business for at least four years, and the host and registrar will not allow the business owner to try to prove their property.
we set up a new site, but the old site is still there and there are still people who call the previous number.

Is there any acceptable way to help boost the new site as a result of the search instead of the previous one? I cannot configure a 301, but the new site has a list of companies, is linked by local CoC and the BBB, has labels for products, services, local businesses, is responsive, has analysis, bing and search console links, but I am hoping to do more …

ssl: vsftpd cannot be accessed from a specific VPN

When I connect through openvpn to a vsftpd server using explicit tls, it fails as follows:

Status: Resolving address of   
Status: Connecting to w.x.y.z:21...                         
Status: Connection established, waiting for welcome message...     
Trace:  CFtpControlSocket::OnReceive()      
Response:   220 (vsFTPd 3.0.2)
Trace:  CFtpLogonOpData::ParseResponse() in state 1
Trace:  CControlSocket::SendNextCommand()
Trace:  CFtpLogonOpData::Send() in state 2
Command:    AUTH TLS
Trace:  CFtpControlSocket::OnReceive()
Response:   234 Proceed with negotiation.
Trace:  CFtpLogonOpData::ParseResponse() in state 2
Status: Initializing TLS...
Trace:  tls_layer_impl::client_handshake()
Trace:  tls_layer_impl::continue_handshake()
Trace:  TLS handshake: About to send CLIENT HELLO
Trace:  TLS handshake: Sent CLIENT HELLO
Trace:  tls_layer_impl::on_send()
Trace:  tls_layer_impl::continue_handshake()
Trace:  tls_layer_impl::on_read()
Trace:  tls_layer_impl::continue_handshake()

w.x.y.z is a public IP address

The vsftpd configuration is:

rsa_private_key_file= /etc/letsencrypt/live/   


I can connect without problems from the internet only using that specific vpn connection that fails.

Is it an incorrect vsftpd configuration or is it a firewall / network problem?