The free version of CHITUBOX is the only slicer that natively supports Longer 3D Orange10 .igs file generation on Linux, MacOS, and Windows 7/10.

https://www.chitubox.com/index.html

However, when starting the program it makes unauthorized outbound HTTPS connections even when setting up the program to not send anonymous usage statistic, or check for updates. 

The specific IP in question is 47.254.50.23 on https  a.k.a. Alibaba.com LLC.

On Ubuntu kernels you can simply:

1. Create a script file "NOCHITUBOX.sh" to run the binary downloaded from the website with the path to the extracted path:

#!/bin/bash

cd /home/myuser/CHITUBOX_V161

unshare -r -n /home/myuser/CHITUBOX_V161/CHITUBOX

exit 0

2. make the script runable

chmod 700 NOCHITUBOX.sh

3. and edit your menu links to run the script instead of the binary directly

Note, unshare will sandbox the program in a separate network-stack area that does not contain any valid adapters, and thus blocks the https connection shenanigans. This works if CONFIG_NET_NS=y is enabled on a modern Linux kernel like Ubuntu 16> does by default

If anyone has further details, than feel free to share. =)