Ubuntu 16.04下Python3.5.2安装Netmiko失败：PyNaCl报错求助

Hey Phil, no need to apologize at all—we’ve all struggled with finicky package installs on older systems! Let’s get this Netmiko setup sorted out.

What’s Causing the Issue? #

The error you’re seeing stems from the libsodium library (a dependency of PyNaCl) crashing during its test suite with "Illegal instruction" errors. This happens because newer versions of PyNaCl try to compile a modern libsodium build that uses CPU instructions your system might not support, or it’s incompatible with the older Ubuntu 16.04/Python 3.5.2 environment.

Step-by-Step Fixes #

Here’s what to try, in order:

1. Ensure System Dependencies Are Fully Installed
   Even if you think you have libsodium installed, make sure you have the development packages and build tools required for compiling:

   sudo apt-get update && sudo apt-get install build-essential libsodium-dev libffi-dev python3-dev
   

   This ensures all the headers and tools needed to build PyNaCl are present.

2. Install a Compatible PyNaCl Version
   Newer PyNaCl versions drop support for Python 3.5 and older Ubuntu releases. Install a version that’s known to work with your setup:

   pip3 install pynacl==1.3.0
   

   This version of PyNaCl uses a libsodium build that’s compatible with older CPU instruction sets and won’t trigger the illegal instruction errors.

3. Install Netmiko (With a Compatible Version if Needed)
   Once PyNaCl installs successfully, install Netmiko. If you run into issues with the latest Netmiko (which also drops Python 3.5 support), use a compatible version:

   # For latest version compatible with Python 3.5
   pip3 install netmiko==2.4.2
   

   Or if the latest version works (some might still have partial support):

   pip3 install netmiko
   

4. Fallback: Use Precompiled Binary Packages (Avoid Compiling)
   If compiling still fails, try forcing pip to use precompiled "wheel" packages instead of building from source:

   pip3 install --only-binary :all: pynacl==1.3.0
   

   This skips compiling libsodium entirely and uses a pre-built binary that’s safe for your system.

Why This Works #

Ubuntu 16.04 and Python 3.5.2 are end-of-life, so newer packages often drop support for them. By pinning to older, compatible versions of PyNaCl and Netmiko, you avoid the compatibility issues with modern library builds.

内容的提问来源于stack exchange，提问作者philb