Monthly Archives: December 2020

Unsupported DEB-based OS: /etc/os-release ID ‘kali’

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Unsupported DEB-based OS: /etc/os-release ID ‘kali’. You can get the above error if you try to install AMD drivers on Kali Linux. Looks like by default they are looking for a system that is Ubuntu, LinuxMint or Debian.

You can resolve the issue by opening up the “amdgpu-pro-install” file and adding more OS’s that it can check for.

vi ./amdgpu-pro-install

Scroll down to line 147 where is says

ubuntu|linuxmint|debian)

and change it to 

ubuntu|linuxmint|debian|kali)

The code function should look like the following.

142 function os_release() {
143         if [[ -r  /etc/os-release ]]; then
144                 . /etc/os-release
145
146                 case "$ID" in
147                 ubuntu|linuxmint|debian|kali)
148                         :
149                         ;;
150                 *)
151                         echo "Unsupported DEB-based OS: `
152                                 `/etc/os-release ID '$ID'" | stderr
153                         exit 1
154                         ;;
155                 esac
156         else
157                 echo "Unsupported OS" | stderr
158                 exit 1
159         fi
160 }

Save a close the file and install the AMD drivers

./amdgpu-pro-install -y --opencl=legacy,rocm --headless

Looking at trying to install AMD drivers for mining? Check out the following link
Install RX 580 Mining Drivers on Debian Based Distributions

More info on Stack Exchange
https://elementaryos.stackexchange.com/questions/24282/cant-install-amd-drivers-on-elementaryos-hera-unsupported-deb-based-os

An upgrade from ‘disco’ (19.04) to ‘focal’ (20.04) is not supported with this tool.

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Unfortunately once a version of Ubuntu becomes unsupported you can run into problems upgrading to the latest version. As is the case when you try to upgrade disco to focal. Ubunut 19.04 to 20.04.

A work around is to update the apt sources and then run an update

Update Apt Sources with.

sudo sed -i 's/disco/focal/g' /etc/apt/sources.list

Now Upgrade with the following two commands. 

sudo apt update
sudo apt -y dist-upgrade

More info at the following link.

https://www.knowledgepublisher.com/article/1452/solution-an-upgrade-from-disco-to-focal-is-not-supported-with-this-tool.html

Troubleshooting DNS CPU Usage on Mikrotik Router

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Problem : Lots of CPU utilization. Profile shows a good bit of it is DNS related.

DNS eating CPU on Router

The router is setup to allow DNS to pass through to web servers so rDNS and other records can be looked up and resolved. This is a specific IP block that gets it’s addresses from the router. The firewall rules explicitly allow this address range. We’ll say 192.168.88.0/24, and blocks everything else. This works for the web servers. But why are we still getting a bunch of CPU utilization with DNS?

As it turns out, the firewall rule that allows the server address range also includes routers own address! So we have unintentionally whitelisted DNS access to our router.

To resolve the issue we can add another firewall rule that explicitly blocks DNS traffic to the routers IP address. We are using two rules, one to block TCP and the other UDP.

ip firewall filter add chain=input dst-address=192.168.88.1 protocol=6 dst-port=53 in-interface-list=WAN action=drop
ip firewall filter add chain=input dst-address=192.168.88.1 protocol=17 dst-port=53 in-interface-list=WAN action=drop

Rules 6 & 7 are the two new rules we just applied. 14 & 15 block input to the router, however rules 8 & 9 inadvertently allowed access to the router’s public IP.

Firewall Rules for Router

The Result? Our CPU usage dropped!

CPU Usage dropped after adding DNS firewall rules.

Quite dramatically too as the following LibreNMS screenshot shows.

LibreNMS CPU graph showing the overall CPU utilization improvement

For more information about DNS Amplification attacks, refer to the following links.

https://ask.wireshark.org/question/6865/dns-amplification-attack/
https://security.stackexchange.com/questions/237127/why-would-hackers-attack-a-dns-server-with-a-dos

Nanominer – Lower intensity for GPU

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https://help.nanominer.org/article/168-gpu-and-cpu-control

By default Nanominer sets the memTweak option to 1. This slightly improves memory timings. However it introduces a little bit of UI lag. This can be a problem if you are trying to use your computer for other tasks. The simple resolution is to change/add the memTweak setting to 0.

memTweak=0

Example config

wallet = WALLET_ADDRESS
; Coin to mine.
coin = ETH
; (Optional) Rig (worker) name.
rigName = EthMiner
memTweak=0