Virtualbox network – two guests connected to each other with only one having internet access

I’ve been poking around with this for quite a while and can’t get it working. I’m using Virtualbox and I’m having to linux VMs – let’s call them VM1 and VM2. There is also a linux-host. The idea I want to achieve is to have something like this:

enter image description here

So there’s this brilliant drawing of mine. So VM1 cannot have internet access. VM2 is connected with VM1 (they can ping each other) but also VM2 is connected (through bridge adapter I suppose) to Host which has actual internet access causing it that VM2 has internet access too. The main idea is to keep VM1 out of the internet whatsoever. Could you help me with that? I suppose it must be really simple but I’ve been trying for quite a long now and I can’t really get it done.

What I’ve tried so far is to make bridge adapter between VM2 and Host, add host only adapter on VM1 and VM2 but I couldn’t really get IP of VM1. Trying nmap through DHCP IPs on VM2 caused finding a lot of weird stuff but not an actual VM1.

Number of Connected simple graphs with n vertices

Is there a relation between numbers of simple graphs and simple connected graphs on n vertices? After observing n=1,2,3,4…., I noticed that the number of connected graphs is at least half of the total number of simple graphs. How can we prove that?

macbook pro – HDD connected to mac with thunderbolt 3 to USB 3 adaptor is not recognized

I have a MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports) running High Sierra. I usually leave my HDD on with the adaptor, then plug the adapter into the same port every time I need to use it. However, usually the HDD will not show up in Finder, diskutil list, or lsusb. Replugging does not work. Connecting it to another port will work, as well as plugging in another device (in my case, Belkin USB C to LAN adaptor) to the port not working before reconnecting the HDD to the same port. Is there any way I can troubleshoot what is happening? This problem is really annoying because I need to unplug the Belkin adaptor to make the HDD connect, and I lose internet for a period of time which means I need to reconnect network mounts and open YouTube tabs.

bitcoincore development – How do I view information on the peers my Bitcoin Core full node is connected to?

As 0xB10C posts here you can get a peer dashboard to bitcoin-cli that looks like this.

netinfo dashboard

You can get this dashboard by using

watch ./src/bitcoin-cli -netinfo 4

and you can use the -asmap flag too.

This feature was merged into Bitcoin Core in September 2020 so to use it today you will either need to build master or wait for a future major release. (The feature was built by Jon Atack.)

sharepoint online – Find which Flow (Power Automate) is connected to my SPO List

We have a number of Lists & Libraries in SharePoint Online, and a number of Power Automate Flows that were created by another team (they don’t work with us anymore). The names given to those Flows are a bit cryptic and there’s hundreds of them. So now the question is- how do I find out which Flow is connected to which List or Library? I don’t want to open each and every Flow manually. Thought there must be a better way to find this out? Also, how can I take ownership of those Flows (once I find the relevant ones)?

calculus of variations – Are these two subsets of matrices rank-$1$ connected?

Let $s>0$ be a positive number (in my application $s>frac{1}{2}$, but I am not sure if it matters here). Let $M_2$ be the set of all real $2 times 2$ matrices, and define the following sets:

$$X={ A in M_2 , |, det A=s^2 ,text{and },sigma_1(A)=sigma_2(A)=s }, , ,,,,Y={ A in M_2 , |, sigma_1(A)=0, sigma_2(A)=1 },$$

where $sigma_1(A) le sigma_2(A)$ are the singular values of $A$.

(The point of the condition $det A=s^2$ in the definition of $X$ is to make $det A$ positive, i.e. to exclude $det A=-s^2$).

Question: Do there exist $A in X, B in Y$ such that $A-B$ has rank $1$?

Is it safe to type a password in a VNC client connected to a server to access another server?

I am using VNC GUI client from my Desktop to connect to a remote (ubuntu) server, say S1. From the remote server (S1), I will be logging into another server (say S2) via SSH. Via VNC client, I will be typing in the SSH password of S2 on putty running on S1 to gain access to S2. Is this a safe way of doing things?

javascript – How to make a snake game where each snake tile follows it’s connected tile

I want to make a basic snake game. It has a head and a series of tails that occupy a tile in a grid. The first tail in the series is adjacent to the head. and each tail that comes after is adjacent to the previous tail. Head can move in four directions and the first tail moves to head’s previous position, and each other tail moves to the previous position of the previous tail, as they follow each other.

How can I model this as data, and update it for movement.

I’ve tried this but that’s a little doesn’t work.

p = {
  x=0,
  y=0,
  tails={}
}

function init_tail(dx,dy)
   return {
      x=0,
      y=0,
      dx=dx,
      dy=dy
   }
end
-- Initialization
add(p.tails, init_tail(0,1))
add(p.tails, init_tail(0,1))
add(p.tails, init_tail(0,1))

local last = p
for tail in all(p.tails) do
   local tx = last.x + tail.dx
   local ty = last.y + tail.dy
   tail.x = tx
   tail.y = ty
   last = tail
end
-- Movement
local last = p
for tail in all(p.tails) do
   tail.dx = -last.dx
   tail.dy = -last.dy
   local tx = last.x + last.dx + tail.dx
   local ty = last.y + last.dy + tail.dy
   tail.x = tx
   tail.y = ty
   last = tail
end

This is what I have so far: snake game

vulnerability – Is there a legitimate reason for a USB-ethernet hardware device to have been connected to my laptop?

There was an unknown network adapter in my device manager. I found out it was for a USB-RJ45 ethernet device, which I have never even seen before. This device was not present when I bought the machine. As far as I have researched, it is not installed by any software or devices I use.

I’m concerned because there is a known vulnerability in Windows that’s exploited using these devices. A malicious person with access to the device could have stolen my credentials and logged in. (Google Usb-ethernet windows vulnerability if you don’t believe me.)

I believe the police or another malicious party exploited that vulnerability, and they used it to install a keylogger and acquire my hardware info. Is the presence of this device suspicious enough, from an information security standpoint, to support my belief? What would you do if you discovered the same on an enterprise machine?

routing – How to route a subnet network connected on the VPN server and make it available to VPN Clients

I have an OpenVPN Server that’s connected to an overlay network which I’d like to make it available from a VPN Client. I added the route to the overlay network 172.63.0.0 on openvpn.conf making the OpenVPN Server host itself 0.0.0.0 as the gateway because it is able to reach the intended overlay network. I watched the tcpdump on tun0 and it seems that the VPN is able to resolve the IP address on the overlay network that I’m trying to reach from the VPN Client but nothing comes back so I’ve made sure the VPN Server host was able to forward TCP packets and had the proper firewall exception but it still won’t work. This system is running on a docker container but I think it shouldn’t be relevant as network configuration goes. I don’t know how but people have been able to work around this problem with some disadvantages by configuring NATs discussed here but still unable to do it through routing.

server 192.168.255.0 255.255.255.0
verb 3
key /etc/openvpn/pki/private/private.key
ca /etc/openvpn/pki/ca.crt
cert /etc/openvpn/pki/issued/certificate.crt
dh /etc/openvpn/pki/dh.pem
tls-auth /etc/openvpn/pki/ta.key
key-direction 0
keepalive 10 60
persist-key
persist-tun

proto udp
# Rely on Docker to do port mapping, internally always 1194
port 1194
dev tun0
status /tmp/openvpn-status.log

user nobody
group nogroup
comp-lzo no

### Route Configurations Below
route 192.168.254.0 255.255.255.0
route 172.63.0.0  255.255.0.0  0.0.0.0

### Push Configurations Below
push "block-outside-dns"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
push "comp-lzo no"

Firewall config:

bash-5.0# iptables -nvL
Chain INPUT (policy ACCEPT 2 packets, 228 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    4   228 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain OUTPUT (policy ACCEPT 2 packets, 212 bytes)
 pkts bytes target     prot opt in     out     source               destination