Given a set of ports is there one that is more likely to bypass a firewall?

I’ve been trying to solve a homework question in a beginner infosec class, and I was stumped on an issue and I didn’t really know of the right place to ask. If it isn’t then please let me know.

Given the following ports,





if somebody was developing malware, which would be the most likely to be used by it to bypass the firewall?

I know that 53 and 443 are DNS and HTTPS respectively.

My way of thinking about the problem is that it’s likely a firewall would be set up to not drop incoming HTTPS traffic so that would be the best one to develop malware for, but I feel like there’s possibly a trick to the question I’m missing. Also it’s probably possible to eliminate UDP 8080 because it falls out of the commonly used UDP service range, meaning it’s likely to be blocked by default.

Any insight or explanation would be helpful. Thanks!

Ubuntu 19.04 with gdm3 REFUSES to work with HDMI nor mini display ports

I’m at my wits end here. I’m running 19.04 in dualboot(same SSD) with win 10.

On win10 everything is peachy; HDMI and mini display both work perfectly.

Come to Ubuntu 19.04, everything fails. Neither port works(xrandr never pulls up hdmi port as below):

Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm    1920x1080    144.00*+  60.01    60.00    59.97    59.96    59.93      1680x1050     84.94    74.89    69.88    59.95    59.88      1600x1024     60.17      1400x1050     85.00    74.76    70.00    59.98      1600x900      59.99    59.94    59.95    59.82      1280x1024     85.02    75.02    60.02      1440x900      59.89      1400x900      59.96    59.88      1280x960      85.00    60.00      1440x810      60.00    59.97      1368x768      59.88    59.85      1360x768      59.80    59.96      1280x800      59.99    59.97    59.81    59.91      1152x864     100.00    85.06    85.00    75.00    75.00    70.00    60.00      1280x720      60.00    59.99    59.86    59.74      1024x768      85.00    75.05    60.04    85.00    75.03    70.07    60.00      1024x768i     86.96      960x720       85.00    75.00    60.00      928x696       75.00    60.05      896x672       75.05    60.01      1024x576      59.95    59.96    59.90    59.82      960x600       59.93    60.00      832x624       74.55      960x540       59.96    59.99    59.63    59.82      800x600       85.00    75.00    70.00    65.00    60.00    85.14    72.19    75.00    60.32    56.25      840x525       85.02    74.96    69.88    60.01    59.88      864x486       59.92    59.57      800x512       60.17      700x525       85.08    74.76    70.06    59.98      800x450       59.95    59.82      640x512       85.02    75.02    60.02      720x450       59.89      700x450       59.96    59.88      640x480       85.09    60.00    85.01    72.81    75.00    59.94      720x405       59.51    58.99      720x400       85.04      684x384       59.88    59.85      680x384       59.80    59.96      640x400       59.88    59.98    85.08      576x432      100.11    85.15    85.09    75.00    75.00    70.00    60.06      640x360       59.86    59.83    59.84    59.32      640x350       85.08      512x384       85.00    75.03    70.07    60.00      512x384i      87.06      512x288       60.00    59.92      416x312       74.66      480x270       59.63    59.82      400x300       85.27    72.19    75.12    60.32    56.34      432x243       59.92    59.57      320x240       85.18    72.81    75.00    60.05      360x202       59.51    59.13      360x200       85.04      320x200       85.27      320x180       59.84    59.32      320x175       85.27   

And I’ve tried everything Google has. All failed. I installed and switched to LightDM, no use. I reinstalled, have gdm3 only running, no use. Any ideas? This is getting super frustrating 🙁

Connecting the laptop to my dell monitor brings up the message from the monitor: No hdmi signal from your device

ADD: I’ve switched back from proprietary nvidia-driver-418 to noveau drivers, with no luck either. I opened nvidia settings and am currently running on the iGPU selection.

2/4 USB Ports no longer detected

I have an MSI gs63vr with 3 USB3 ports and 1 USB2 port. Two of the USB3 ports stopped working (the ones in the back) but the other 2 work just fine. I have tried editing /etc/default/grub many times, to no avail.

The ports themselves don’t seem to be the problem, I can charge devices with them just fine, they just aren’t detected by ubuntu (I checked lsusb to make sure).

Any suggestions would be greatly appreciated!

Setting IP to static results in some unreachable ports

I had Virtualmin running perfectly on my Ubuntu 18.04 I set a new internal static IP (Before it was DHCP) with netplan as following:

network:   version: 2   renderer: networkd   ethernets:     enp6s0:       dhcp4: no       addresses: []       gateway4:       nameservers:         addresses: [,] 

After that I forwarded all the necessary ports in my router. The router had a submask so I changed it to

Now: the ports 22, 465, 587, 3306 are still reachable and the ports 20, 80, 443, 10000, 20000 are closed now/ Err_Conn_Refused (Checked with Before the IP change, all these ports were open and running.


doesn’t work either from a local network computer

Firewall seems to be OK, I tried to reinstall Virtualmin in the hope that it would reconfigure it correctly, no luck. I also tried to restore it and use dhcp again, but it’s still the same error. I assigned 10 Gb ram to virtualmin, so it shouldn’t be this either. Virtualmin is up and running, as far as I can understand.

USB ports – Confusing

USB ports on the right-hand side of my laptop don’t work on my laptop when Ubuntu is being used. (The ones on the left work!!) USB ports on the left-hand side of my laptop don’t work on the same laptop when Windows is being used. (The ones on the right work!!)

Is this related?

Ubuntu is my primary OS and I want all the USB ports to work with it. Any suggestions?

All ports on DELL xps-13-9380-laptop don’t work anymore

All of my 3 ports on my dell xps-13-9380-laptop don’t work anymore. These are the specs of my laptop:

I tried to update my BIOS by following this instructions:

I also read in this post that downloading the update to the firmware would fix it:

However, it says I need to download the .exe file to a USB stick. Since all my ports don’t work, I can’t do that, obviously.

I ran this command in my terminal

fwupdmgr get-updates

and got this result:

No upgrades for XPS 13 9380 System Firmware, current is,,,,

I assume my firmware is uptodate?

What else can I do other than sending it back to DELL or resetting to factory settings and installing everything again?

Several ports open to the public (

I was told by Amazon that my ports are open to public . But still no idea on how to closed. Kindly help.

I had setup iptables and other rules, but this quite new for me.

The below is the text from Amazon—

We see that you’ve denied outbound connections to the IP of the destination domain , however in reviewing your Amazon EC2 instance(s), it appears you have left several ports open to the public ( Leaving ports open like this can leave your instance vulnerable to compromise and unwanted network activity in general.

TCP 22
TCP 80
TCP 443

Firebase ports scanning using nmap

Purely for research purposes used nmap to check security of my application deployed to Firebase. However, there some questions which I can’t understand:

  1. Why Firebase has open so many ports? Something like few hundreds.
  2. Almost on every port I’m getting an error auth-owners: ERROR: Script execution failed without any information about it. Why is that? The only one which gives some information are the following ports: 80, 443, 5269, and 65389.
  3. Is TCP Sequence Prediction difficulty=17 and Network Distance 2 hops a good or bad result?
  4. What means ssl-date: TLS randomness does not represent time?
  5. What means IP ID Sequence Generation: Incremental?
  6. What are Aggressive OS guesses?
  7. I could see the open few hundreds of ports only after first scan, later on couldn’t replicate this. Is it possible that Firebase/Google closed the ports or blocked me for some of them? In second scan and every other I could see only information about open ports 80, and 443 with a log “Not shown: 998 filtered ports”.
  8. I did test this on Kali Linux using VirtualBox. In the nmap output I can see Running: Oracle Virtualbox, OS CPE: cpe:/o:oracle:virtualbox, OS details: Oracle Virtualbox, is it about my system or the scanned website hsoted on Firebase?

Even answers for some of this questions would be already really appreciated!

How can I install Ubuntu on a HP Pavillion DM1 with broken USB ports?

I was recently given an old computer (HP Pavilon Dm1 – I think it’s about 6 years old). All 3 USB ports on the computer are broken. So I have to install Ubuntu through Internet network adapter boot, but I’m a little lost how to do that. I was planning to install Ubuntu 19.04 to this old computer on SSD drive.

How can I install Ubuntu on a device with broken USB ports?