I just tried the command on an amd64 machine:
root@Kali:~# ettercap -G
I don't get a segfault.

Can you check if you have the latest version? (dpkg -s ettercap-common)
As it's a Debian package, if you still have the issue with the latest version (1:0.8.3-6), you should report the issue directly in Debian (with the details about pacakge version, architecture...):
See https://kali.training/topic/filing-a-good-bug-report/ 6.3.3.2. Filing a Bug Report in Debian

Since this is not reproducible on our side, before fiiing a bug to Debian you should install debug packages and generate a backtrace of the segfault. You might want to double check if you can reproduce it on a clean install too.

https://wiki.debian.org/HowToGetABacktrace

@rhertzog
@sbrun

I've the same issue + latest version.

Thanks.

@atdtphreaker thanks for your feedback.
But as we don't reproduce the issue, we can't debug it. We (Kali or Debian) need a backtrace as @rhertzog explained.

@sbrun

You're welcome. I understand that you don't 'reproduce' the issue, but I just wanted to inform you so it is known + documented.

Thank, I appreciate your time.

I think you need to modify your /etc/ettercap/etter.conf

Uncomment

if you use iptables:

#redir_command_on = "iptables -t nat -A PREROUTING -i %iface -p tcp -s %source -d %destination --dport %port -j REDIRECT --to-port %rport"
#redir_command_off = "iptables -t nat -D PREROUTING -i %iface -p tcp -s %source -d %destination --dport %port -j REDIRECT --to-port %rport"

pendant for IPv6 - Note that you need iptables v1.4.16 or newer to use IPv6 redirect

#redir6_command_on = "ip6tables -t nat -A PREROUTING -i %iface -p tcp -s %source -d %destination --dport %port -j REDIRECT --to-port %rport"
#redir6_command_off = "ip6tables -t nat -D PREROUTING -i %iface -p tcp -s %source -d %destination --dport %port -j REDIRECT --to-port %rport"

i did a backtrace and this is the result i got:

root@kali:~# gdb --args ettercap -G
GNU gdb (Debian 8.3.1-1) 8.3.1
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ettercap...
(No debugging symbols found in ettercap)
(gdb) bt
No stack.
(gdb) run
Starting program: /usr/bin/ettercap -G
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

ettercap 0.8.3 copyright 2001-2019 Ettercap Development Team

[New Thread 0x7ffff45c7700 (LWP 3553)]
[New Thread 0x7ffff3dc6700 (LWP 3554)]
[New Thread 0x7ffff0a06700 (LWP 3555)]
[Detaching after fork from child process 3556]
[Detaching after fork from child process 3557]

Thread 1 "ettercap" received signal SIGSEGV, Segmentation fault.
strstr_sse2_unaligned () at ../sysdeps/x86_64/multiarch/strstr-sse2-unaligned.S:40
40 ../sysdeps/x86_64/multiarch/strstr-sse2-unaligned.S: No such file or directory.
(gdb) bt
#0 0x00007ffff7dad62d in strstr_sse2_unaligned () at ../sysdeps/x86_64/multiarch/strstr-sse2-unaligned.S:40
0000001 0x00007ffff7f6bb5b in str_replace () at /lib/libettercap.so.0
#2 0x00007ffff7f610f8 in ec_redirect () at /lib/libettercap.so.0
#3 0x00007ffff7f6a666 in ssl_wrap_init () at /lib/libettercap.so.0
0000004 0x000055555555796b in main ()

can someone please explain the problem as this has gone slightly over my head