How to properly downgrade openssl version under Ubuntu 18.04

Question

I need to install some proprietary antivirus software on my 18.04 system because of company policy. The thing is, it requires an older version of OpenSSL to even install and then work, i.e. Ubuntu 18.04 uses 1.1 series, and the software depends on version 1.0. They don't seem to be planning to change that in the near future since Linux is not a priority platform for them.

Apt does not see any older versions than 1.1 in the repositories. I managed to find a .deb file with some 1.0.1 version, but obviously just installing it breaks dependencies throughout the whole system and apt wants me to run installation fix (which just installs the newest version).

Removing the currently installed OpenSSL version (to later install the old one) is out of the question since that also removes lots of important packages that I require for work (including the whole Gnome environment).

Is there a way to properly downgrade OpenSSL to 1.0 without breaking the system, or at least have both versions installed (and just direct the software and its installer to the older one)?

Solution 1

You should avoid attempting to downgrade OpenSSL, and use a VM or a container with an older OS for things where you need to use the older OpenSSL versions.

It is not safe to downgrade OpenSSL to a 1.0.x version because many things will fail to build or operate properly due to the varying codebase changes within the OpenSSL codebase over time.

If you need a different and older OpenSSL, I would suggest that you use a VM or container of the older Ubuntu with the older OpenSSL to do this, rather than downgrade your OpenSSL in this manner.

Solution 2

You can try the following:

sudo apt-get install -y --allow-downgrades openssl1.0=1.0.2n-1ubuntu5.1 
echo "export OPENSSL_DIR=/usr/lib/ssl1.0/" >> ~/.bashrc

Comments

[steeldriver]

I don't know of a way to do that with apt but you may be able to arrange for the specific software to be launched in an environment where it can use "private" versions of the required shared libraries (using LD_LIBRARY_PATH for example)

[Thomas Ward]

It is not safe to downgrade OpenSSL to a 1.0.x version because many things will fail to build or operate properly. If you need a different OpenSSL, I would suggest that you use a VM or container of the older Ubuntu with the older OpenSSL to do this, rather than downgrade your OpenSSL in this manner.