If Cisco Packet Tracer installation on Ubuntu 23.10 gives you this error

    This package is uninstallable
    Dependency is not satisfiable: libgl1-mesa-glx

link for guide

If your Cisco Packet Tracer installation shows this error

 The following packages have unmet dependencies:
 packettracer: depends: libgl1-mesa-glx but it is not installable

Step 1 Download dependecies archives

click here for download dependecies

Step 2 install gdebi

  sudo apt install gdebi

Step 3 install dependecies

go to the Downloads page

in terminal

cd /home/yourUser/Downloads

install dependencies

  sudo gdebi ./libegl1-mesa_23.0.4-0ubuntu1.22.04.1_amd64.deb ./libgl1-mesa-glx_23.0.4-0ubuntu1.22.04.1_amd64.deb

Step 4 install CiscoPacketTracer

  sudo gdebi ./Packet_Tracer821_amd64_signed.deb 

or

  sudo gdebi ./YOURPACKETTRACKERARCHIVE.deb