Wednesday 4 December 2097

DDoS attack detection solution - FastNetMon

Hello! :) As you know I'm an author of DDoS detection application called FastNetMon.

FastNetMon allows you to find out host which was a DDoS attack target and apply some actions to mitigate it. Mitigation can be implemented using BGP Blackhole (which blocks all traffic to/from host on ISP level) or you can use BGP Flow Spec to filter out only malicious traffic. As most flexible option you can use script call.

FastNetMon provides lots of information about your network and provides nice way to access it using Grafana:

FastNetMon supports all equipment available on market and implement following network telemetry protocols:
  • sFlow v5
  • Netflow v5, v9, v10
  • SPAN/Mirror

To learn more check official site of project:

Saturday 2 March 2024

How to create bootable USB for Windows 2022 server on Ubuntu 22.04

NB! Sadly this guide below did not work on my system (apparently because it's not very recent system) and I decided to use WoeUSB instead. 

It's very easy to use:

sudo ./woeusb-5.2.4.bash --device ~/Documents/Window/SERVER_EVAL_x64FRE_en-us.iso /dev/sdX

Please note that it will overwrite all data on USB stick.

Example output:

WoeUSB v5.2.4


Info: Mounting source filesystem...

Info: Wiping all existing partition table and filesystem signatures in /dev/sda...

/dev/sda: 8 bytes were erased at offset 0x00000200 (gpt): 45 46 49 20 50 41 52 54

/dev/sda: 8 bytes were erased at offset 0x729bffe00 (gpt): 45 46 49 20 50 41 52 54

/dev/sda: 2 bytes were erased at offset 0x000001fe (PMBR): 55 aa

/dev/sda: calling ioctl to re-read partition table: Success

Info: Ensure that /dev/sda is really wiped...

Info: Creating new partition table on /dev/sda...

Info: Creating target partition...

Info: Making system realize that partition table has changed...

Info: Wait 3 seconds for block device nodes to populate...

mkfs.fat 4.2 (2021-01-31)

mkfs.fat: Warning: lowercase labels might not work properly on some systems

Info: Mounting target filesystem...

Info: Copying files from source media...

Splitting WIM: 4127 MiB of 4127 MiB (100%) written, part 2 of 24%

Finished splitting "./sources/install.wim"

Info: Installing GRUB bootloader for legacy PC booting support...

Installing for i386-pc platform.


Installation finished. No error reported.

Info: Installing custom GRUB config for legacy PC booting...

Info: Done :)

Info: The target device should be bootable now

Info: Unmounting and removing "/tmp/woeusb-source-20240302-155025-Saturday.g0vizR"...

Info: Unmounting and removing "/tmp/woeusb-target-20240302-155025-Saturday.T2VU0b"...

Info: You may now safely detach the target device

As first step format USB stick by creating new GPT partition table on it:

Then create single partition on it using NTFS file system:

Then review changes:

After that you will see that this partition will be mounted in file manager:

After that download ISO image for Wndows 2022 server from official web site and click twice on downloaded ISO and it will be mounted too:

Then select all files from mounted ISO disk to mounted NTFS partition on USB disk:

Wait until finish and unmount it using unmount button on left side:
Please be patient as unmount will take significant time:


Sunday 21 January 2024

jTAG / UART / serial console access for ROCKPro64 with CH340 UART USB

I bought ROCKPro64 quite long time ago and it's still pretty good even in 2024. So I decided to install official Debian for it to use it for NAT64 gateway and home automation platform. 

To install Debian I need console access as HDMI does not work until you install Linux Distro which supports it.

So I decided to play with serial port access. On SBC you need to plug 3 pins to Pi-2-bus with following order.

On CH340 you need to plug them in following order:

And yellow jumper need to be in 3V3 mode this way:

Then you need to plug CH341 to your PC and check that it recognised correctly in dmesg:

[ 6981.858478] usb 1-5: new full-speed USB device number 23 using xhci_hcd

[ 6982.107488] usb 1-5: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.64

[ 6982.107492] usb 1-5: New USB device strings: Mfr=0, Product=2, SerialNumber=0

[ 6982.107494] usb 1-5: Product: USB Serial

[ 6982.120247] ch341 1-5:1.0: ch341-uart converter detected

[ 6982.134269] usb 1-5: ch341-uart converter now attached to ttyUSB0

It may not connect from first attempt but you can try it multiple times to get required results.  

After that you can run screen or minicom on your Linux box:

screen /dev/ttyUSB0 1500000

And finally reboot SBC using power (keep it for 5+ seconds) or reset button and then you will see boot sequence:

Hit any key to stop autoboot: 1 

switch to partitions #0, OK


Retrieving file: /extlinux/extlinux.conf

Enter choice: 1:        Debian-Installer

Retrieving file: /initrd.gz

Retrieving file: /dtbs/rockchip/rk3399-rockpro64.dtb

Moving Image from 0x2080000 to 0x2200000, end=4050000


   Booting using the fdt blob at   Loading Ramdisk to ef112000, OK

   Loading Device Tree to 00000000ef0ff000, end 00000000ef111300OK

Starting kernel ...

My guide was based on this reference guide. 

In some cases device may refuse loading when TXD cable is plugged and you will need temporarily unplug it.

Sunday 15 October 2023

Using TP Link TL-SG108E web UI configuration tool on Ubuntu 22.04

My research was based on this great post from 2014.

This switch has UI which can be accessed via windows application and has UI which can be accessed via browser. 

Just for entertaining purposes I decided to try Window app on my Ubuntu 22.04 Linux machine.

To do so I installed wine:

sudo apt install wine-development

Then I downloaded version v1.3.10, 2022-04-12 from TP Link web site and unpacked it:


unzip "Easy Smart Configuration Utility"

After that I was able to run installer:

wine Easy\ Smart\ Configuration\ Utility\ v1.3.10.0.exe

Installation was finished successfully and then all exe files were put to "~/.wine/drive_c/Program Files (x86)/TPLINK/EasySmartConfigurationUtility".

And I was able to run it from first attempt:

cd ~/.wine/drive_c/Program Files (x86)/TPLINK/EasySmartConfigurationUtility 

wine Easy\ Smart\ Configuration\ Utility.jar

Unfortunately, it did not find switch:

Then I used trick from article I referenced above. You need to replace by local IP address in your network:

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -t nat -A PREROUTING -p udp -d --dport 29809 -j DNAT --to

After that it worked just fine:

Yay! For some reasons DHCP did not work well and IP address wasn't changed. In this case UI tool solves one of the most annoying issues: IP address discovery. 

I was able to change password to new one but everything else causes wine to crash:

0130:err:ole:com_get_class_object class {597d4fb0-47fd-4aff-89b9-c6cfae8cf08e} not registered

0130:err:ole:com_get_class_object no class object {597d4fb0-47fd-4aff-89b9-c6cfae8cf08e} could be created for context 0x1

0130:err:ole:com_get_class_object class {597d4fb0-47fd-4aff-89b9-c6cfae8cf08e} not registered

0130:err:ole:com_get_class_object no class object {597d4fb0-47fd-4aff-89b9-c6cfae8cf08e} could be created for context 0x1


# A fatal error has been detected by the Java Runtime Environment:


#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6d2efe4d, pid=244, tid=304


# JRE version: 7.0_15-b03

# Java VM: Java HotSpot(TM) Client VM (23.7-b01 mixed mode windows-x86 )

# Problematic frame:

# C  [glass.dll+0xfe4d]  _Java_com_sun_glass_events_KeyEvent__1getKeyCodeForChar@12+0x134d


# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows


# An error report file with more information is saved as:

# C:\Program Files (x86)\TPLINK\EasySmartConfigurationUtility\hs_err_pid244.log


# If you would like to submit a bug report, please visit:


# The crash happened outside the Java Virtual Machine in native code.

# See problematic frame for where to report the bug.


0130:err:msvcrt:_invalid_parameter (null):0 (null): (null) 0 

After reading the Internet I found that this exe file is in fact Java JAR file and I've tried running it using OpenJDK:

sudo apt install default-jre

Sadly it failed miserably:

java -jar Easy\ Smart\ Configuration\ Utility.exe 

Error: JavaFX runtime components are missing, and are required to run this application

As final attempt I've tried using Java from Oracle directly.   You need to download it manually and then unpack it:

sudo tar -xf jre-8u381-linux-i586.tar.gz -C /opt

And run:

/opt/jre1.8.0_381/bin/java -jar Easy\ Smart\ Configuration\ Utility.exe 

Sadly it failed too:

Exception in thread "main" java.lang.reflect.InvocationTargetException

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(

at sun.reflect.DelegatingMethodAccessorImpl.invoke(

at java.lang.reflect.Method.invoke(

at sun.launcher.LauncherHelper$FXHelper.main(

Caused by: java.lang.UnsupportedOperationException: Internal Error


at Method)





at com.sun.javafx.application.PlatformImpl.startup(

at com.sun.javafx.application.LauncherImpl.startToolkit(

at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(

at com.sun.javafx.application.LauncherImpl.launchApplication(

... 5 more

 You may try running older version of Oracle Java as bundled JRE is dated by 2013:

root@station:/home/pavel/.wine/drive_c/Program Files (x86)/TPLINK/EasySmartConfigurationUtility/jre# head COPYRIGHT 

Copyright � 1993, 2013, Oracle and/or its affiliates. 

All rights reserved.

This software and related documentation are provided under a

license agreement containing restrictions on use and

disclosure and are protected by intellectual property laws.

Except as expressly permitted in your license agreement or

allowed by law, you may not use, copy, reproduce, translate,

broadcast, modify, license, transmit, distribute, exhibit,

perform, publish, or display any part, in any form, or by

root@station:/home/pavel/.wine/drive_c/Program Files (x86)/TPLINK/EasySmartConfigurationUtility/jre# cat release 





SOURCE=" .:f37a75bd3959 corba:e5b996dabec6 deploy:3bb10c0238fe hotspot:5b55cef461b0 hotspot/src/closed:759fc4d1d429 hotspot/test/closed:2d8e36f71952 install:0154bd493323 jaxp:a55f67cfe182 jaxws:eaf9b2990670 jdk:87e45d30e24d jdk/make/closed:b83ea3e4144a jdk/src/closed:d8651f160809 jdk/test/closed:7e4b15d6c1bb langtools:c160d7d1616d pubs:06f851196d93 sponsors:2dbf246921cb"


With IP address in hands I was able to access web UI:

And finally I can use capability for which this switch was bought - port mirror:



Saturday 6 May 2023

Ubuntu 22.04 installation on VirtualBox using command line

We use VirtualBox for process of preparing VM images for our product. Sadly some things had to be done manually and we're heading towards full automation and it was an attempt to prepare VM for Ubuntu 22.04 installation from ISO using only command line interface.

NB! If you have IPv4 disabled on your machine you have to enable it as otherwise VM will not have connection and installer may fail. 

Set some variables shared by next steps:

export VM_NAME=Ubuntu2204_TEST_OVA

export VM_ROOT_FOLDER="/home/pavel/VirtualBoxVMs"


By default VirtualBox uses path with nasty space in it and that's why I changed it to custom one without spaces as I do not like spaces and bash agrees with me about it. 

Create VM and register it in VirtualBox:

VBoxManage createvm --name $VM_NAME  --register  --ostype=Ubuntu22_LTS_64 --basefolder=$VM_ROOT_FOLDER

If you plan to use another OS then you can get all list of all OS types using this command:

VBoxManage list ostypes

Then set some basic hardware options:

VBoxManage modifyvm $VM_NAME --ioapic on                     

VBoxManage modifyvm $VM_NAME --memory 16384  --vram 128       

VBoxManage modifyvm $VM_NAME --cpus 8

VBoxManage modifyvm $VM_NAME  --nic1 nat

Then create 150G disk for VM and attach it to it:

VBoxManage createhd --filename $VM_FOLDER/disk.vdi --size 150000 --format VDI

Add SATA controller: 

VBoxManage storagectl $VM_NAME  --name "SATA Controller" --add sata --controller IntelAhci

And attach our disk to it: 

VBoxManage storageattach $VM_NAME  --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium  $VM_FOLDER/disk.vdi

Then add IDE controller to mount ISO disk with installer: 

VBoxManage storagectl $VM_NAME  --name "IDE Controller" --add ide --controller PIIX4 

VBoxManage storageattach $VM_NAME --storagectl "IDE Controller" --port 1 --device 0 --type dvddrive --medium ~/Downloads/ubuntu-22.04.2-live-server-amd64.iso 

VBoxManage modifyvm $VM_NAME  --boot1 dvd --boot2 disk --boot3 none --boot4 none

Then you can run VM:

VBoxManage startvm $VM_NAME

Based on this guide

Thursday 4 May 2023

sign_and_send_pubkey: signing failed for RSA "PIV AUTH pubkey" from agent: agent refused operatio

This error is very annoying and it happens when you use Yubikey for ssh auth and by accident you did not click on Yubikey when you did ssh auth.

After this happens you need to restart machine or ssh agent and all the things to fix it.

When it happens I was able to catch this error log:

sudo systemctl status pcscd.service 

● pcscd.service - PC/SC Smart Card Daemon

     Loaded: loaded (/lib/systemd/system/pcscd.service; indirect; vendor preset: enabled)

     Active: active (running) since Thu 2023-05-04 10:46:27 BST; 2h 39min ago

TriggeredBy: ● pcscd.socket

       Docs: man:pcscd(8)

   Main PID: 2505 (pcscd)

      Tasks: 9 (limit: 38276)

     Memory: 2.6M

        CPU: 88ms

     CGroup: /system.slice/pcscd.service

             └─2505 /usr/sbin/pcscd --foreground --auto-exit

May 04 10:46:27 station systemd[1]: Started PC/SC Smart Card Daemon.

May 04 13:22:18 station pcscd[2505]: 00000000 ccid_usb.c:1566:InterruptStop() libusb_cancel_transfer failed: LIBUSB_ERROR_NO_DEVICE

Then I feed "ccid_usb.c:1566:InterruptStop() libusb_cancel_transfer failed: LIBUSB_ERROR_NO_DEVICE" to Google. 

I have this issue on Ubuntu 22.04 and I've tried version from Ubuntu 22.10 which has version 1.99 of affected package and it did not help. 

Apparently this bugfix may fix this issue and it wasn't part of 1.99 release. Related GitHub issue.

Monday 1 May 2023

Can Mozilla VPN users connect Mullwad servers directly?

I've tried to fix my IPv6 compatibility issues by using Mozilla VPN over NAT64 box this way.

I've tried to improve this setup but it did not work as expected. 

Mozilla VPN uses Mullwad internally and we can find Mullwad's server name using this interface. Just fill "us-nyc-wg-505" in hostname field and after that you will see something like: "".

With this information on our hands we can replace:

Endpoint = x.y.z.y:23662


Endpoint =

Sadly in my case this trick did not work ;(

If you have any advice about ways to fix it please share. 


Mozilla VPN without UI on Ubuntu Linux 22.04 over NAT64

Mozilla VPN service is a really nice service but their UI does not support IPv6 only environment. I use NAT64 box in my network and it does not help either.

Sadly it's known bug and it's still here ;( Luckily I found nice way to workaround it using command line interface. 

I found nice workaround 

Install their Linux app as documented on web site. 

Then we're going to use console app to authenticate. Start authentication process using:

mozillavpn login

Then check that you're successfully authenticated:

mozillavpn status

Then get list of all available servers:

mozillavpn servers

And select your favourite one:

mozillavpn select us-nyc-wg-505

Generate Wireguard configuration using wgconf option which was added recently:

mozillavpn wgconf > mozilla-vpn.conf

Optiwas added recently

Then open mozilla-vpn.conf with editor and alter line like this:

Endpoint = x.y.z.y:23662


Endpoint = 64:ff9b::x.y.z.y:23662

Then establish VPN:

wg-quick up mozilla-vpn.conf

To shutdown it you can use:

wg-quick down mozilla-vpn.conf

In this case we will use NAT64 gateway for connection.

Sunday 30 April 2023

Yubikey ssh on Ubuntu 22.04

Today I did full fresh installation of Ubuntu 22.04 to migrate to new 2T NVME disk from Samsung as I had disk space issues with my old 500G drive. 

After installation I noticed that I cannot use my Yubikey for ssh auth as documented here

I tried to add Yubikey as auth source and it failed with pretty weird error:

ssh-add -s /usr/lib/x86_64-linux-gnu/

Enter passphrase for PKCS#11: 

Could not add card "/usr/lib/x86_64-linux-gnu/": agent refused operation

 This error can mean literally anything.

I've tried running ssh agent manually in foreground mode:

ssh-agent -d

And after that I saw error which sounds like "no available slots".

So I back to guide as I suspected that my Yubikey died and I've sued following command:

sudo ykman list --serials

WARNING: PC/SC not available. Smart card (CCID) protocols will not function.

ERROR: Unable to list devices for connection


That's interesting and this error lead me to this bug and I got fix:

 sudo systemctl start pcscd

After that it worked just fine.

As long term fix you need to enable automatic start on machine boot: 

sudo systemctl enable pcscd

Sadly it's known Ubuntu bug

Thursday 13 April 2023

Yubikey ssh and signing failed for RSA "PIV AUTH pubkey" from agent: agent refused operation

You may face this issue if you use ssh and Yubikey like covered in this guide

Previously I had to reboot machine to address this issue but I found nice trick to get it work.

Originally error looks like:
ssh server
sign_and_send_pubkey: signing failed for RSA "PIV AUTH pubkey" from agent: agent refused operation
root@xxx: Permission denied (publickey).

It may happen when you forgot to tap confirmation on Yubikey and it was just slow.

First attempt to fix it was to kill all ssh agent processes which may be run on system:

ps aux|grep ssh

odintsov   16493  0.0  0.0   7972  5820 ?        S    12:36   0:00 /usr/bin/ssh-agent -D -a /run/user/1000/keyring/.ssh

odintsov   16494  0.0  0.0 164340 11584 ?        SLl  12:36   0:00 /usr/lib/openssh/ssh-pkcs11-helper

odintsov   27798  0.0  0.0   7972  3848 ?        Ss   13:20   0:00 ssh-agent -s

odintsov   27801  0.0  0.0 164340 11572 ?        SLl  13:20   0:00 /usr/lib/openssh/ssh-pkcs11-helper

The best way to kill them is:

pkill ssh

After that we need to start ssh agent again:

eval `ssh-agent -s`

After that load Yubikey key to agent:

ssh-add -s /usr/lib/x86_64-linux-gnu/

For last command I use fancy alias in ~/.bashrc:

alias ssh_add='ssh-add -s /usr/lib/x86_64-linux-gnu/'

It's not clear why Yubikey fails that way. I think it has something to do with ssh-pkcs11-helper being stuck in operation to Yubikey hardware. 


Saturday 8 April 2023

How to enable IPv6 on Google Cloud?

Google Cloud has native support for IPv6 but you need to create special VPC network to use IPv6.

As first step open VPC configuration:

Then create new VPC network and fill all fields as on my screenshot. 

Then configure subnet settings. The most important step to specify dual stack. 

Then you need to create default firewall rules to allow ICMPv6. You may notice that we use number 58 instead of ICMPv6 due to following issue:

Then enable ssh:

After these steps you can create new Compute instances in this region. Then you need to open advanced settings and select our new IPv6 enabled network in list:

And finally select dual stack:

The fun thing that you actually can disable IPv4 completely or you can allocate dedicated IPv6 address for machine. 

Pricing for IPv6 addresses even static ones is mostly free:

Sunday 2 April 2023

Building log4cpp 1.1.4rc3 on msys2 environment on Windows Server 2022

 I got following error during my attempts to build lo4cpp in msys2 environment:

"../include/log4cpp/config-MinGW32.h:27:17: error: 'long long long' is too long for GCC"

It can be easily fixed by commenting following code in file include/log4cpp/config-MinGW32.h

// #define int64_t __int64 

I'll try to report this issue to upstream to have it fixed.  

Got this hint from this blog.

Enabling SSH server on Windows 2022 Datacenter edition

After friend's advice I realised that modern Windows versions have bundled SSH server and that's a best way to work with remote Windows platforms as RDP is not as cool as old good console.

First of all we need to install OpenSSH server component, you can do it this way:

  • Start
  • Settings
  • Apps
  • Apps and Features
  • Optional Features
  • Add Feature
  • OpenSSH Server
Then we need to start it. Search for "Services" in search panel and then open it. Looks for OpenSSH SSH server and then click right mouse button and Start it. 

Then open properties and switch startup type from "manual" to "automatic". We need it to launch it automatically on boot.

After that you can connect to this server via normal SSH client from Linux:
Based on this guide.

Wednesday 1 February 2023

How to control RGB leds on Logitech G Pro X keyboard from Linux?

 Official software is coming only for Windows but fortunately we have nice project for it.

On Ubuntu or Debian it's very easy to install: 

sudo apt install -y g810-led

Then try setting this thing, it's my favourite one so far:

sudo gpro-led -p /usr/share/doc/g810-led/examples/sample_profiles/colors

Install it as default profile:

sudo cp /usr/share/doc/g810-led/examples/sample_profiles/colors  /etc/g810-led/profile