error floating point exception

Thank you for taking the time to report this bug and helping to make Ubuntu better.

I can't reproduce the crash. On an 18.04 VM running iptraf-ng 1:1.1.4-6 with "sudo iptraf-ng -i all -L foo" I get "Unable to open log file" and this seems reasonable given the manpage specification for the -L option.

If you can provide steps to reproduce a crash, please provide them and change the bug status back to New.

I've filed a separate bug in Debian that /var/log/iptraf doesn't get created automatically (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902603). I think this is really quite different from a crash bug though.

The problem is described correctly. There is a lot of documentation on the internet about this "floating point exception" error, which apparently has been introduced in versions prior to Ubuntu 18.04.
https://askubuntu.com/questions/1050008/iptraf-ng-error-floating-point-exception
If you do not want to solve this error, close the incident. Many people had already warned me that reporting an incident on this site is a waste of time.

I also couldn't reproduce this bug.

In a bionic VM, I installed iptraf-ng 1:1.1.4-6:
root@ubuntu:/var/log/iptraf# apt-cache policy iptraf-ng
iptraf-ng:
  Installed: 1:1.1.4-6
  Candidate: 1:1.1.4-6
  Version table:
 *** 1:1.1.4-6 500
        500 http://br.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status
root@ubuntu:/var/log/iptraf#

I created /var/log/iptraf, entered the UI, enabled logging in the config. When starting the monitor, it prompted me for the log file, where I had to correct the log directory (from iptraf-ng to iptraf), but after that, it ran just fine and produced the logfile I indicated:

# ll /var/log/iptraf/
total 12
drwxr-xr-x 2 root root 4096 Jul 9 20:40 ./
drwxrwxr-x 9 root syslog 4096 Jul 9 20:39 ../
-rw-r--r-- 1 root root 360 Jul 9 20:40 andreas.log

I agree that the log directory not being created is a bug. It's even mentioned in the shipped logrotate file:
root@ubuntu:/var/log/iptraf# cat /etc/logrotate.d/iptraf-ng
# Logrotate file for iptraf
/var/log/iptraf/*.log {
 compress
 delaycompress
 missingok
 notifempty
 rotate 4
 create 0600 root root
}

Did you check if your crash produced a crash file in /var/crash? If yes, please upload it to this bug, so we can take a look at the core dump file. It may be related to the type of traffic you are seeing.