For analysis and monitoring purposes it is useful to check the CPU and memory load of network devices. On a LANCOM R&S®Unified Firewall this can be done via the CLI command htop.

This article describes how the current CPU and memory load on a Unified Firewall can be monitored via the CLI command htop.



1) Connect to the Unified Firewall with an SSH client and login with the user gpadmin.

2) Enter the command htop and press the <Enter> button.

3) The tool htop is structured as follows:

  • The digits on the upper left (in this case 1 - 4) represent the logical CPU cores and their load. The load is displayed in different colors.  
    • Blue: Low priority processes
    • Green: Normal priority processes
    • Red: Kernel processes
  • Mem represents the memory load. The load is displayed in different colors.  
    • Green: Used memory
    • Blue: Buffer
    • Yellow: Cache (the cache is freed when the memory load increases)
  • Swp represents the virtual memory. The used virtual memory is always displayed in red.
  • Tasks displays the amount of processes, Threads and currently running threads (in this example there are 101 processes, which are divided into 179 threads, but only one thread is running).
  • Load average displays the CPU load for 1, 5 and 15 minutes. The values have to be multiplied by 100 in order to obtain the percentages (in this case the CPU load in the last minute was 22 %).
  • The Uptime displays the running time of the Unified Firewall since the last reboot.
  • Below the individual processes and threads are shown with with various information, e.g. CPU load (CPU%), Memory load (MEM%) and virtual memory (VIRT).

The load of the shown threads is not additive for threads with the same name. Only the process load (white font) counts to the load but not the corresponding threads. In this case suricata is shown multiple times, but its total memory load is 28.2 %.

For the purpose of clarity it is possible to only display the processes, by changing into the menu Setup Display option and activate the option Hide userland process threads.