尝试为 python3 安装 paramiko

我正在尝试在 Python3 上安装 paramiko3

pip3 install paramiko

但是，我有这个

Downloading/unpacking cryptography>=1.5 (from paramiko)
  Downloading cryptography-2.1.4.tar.gz (441kB): 441kB downloaded
  Running setup.py (path:/tmp/pip_build_andykw/cryptography/setup.py) egg_info for package cryptography
    error in cryptography setup command: Invalid environment marker: python_version < '3'
    Complete output from command python setup.py egg_info:
    error in cryptography setup command: Invalid environment marker: python_version < '3'

如您所见，它似乎与cryptography.

我尝试单独安装软件包，结果相同

Downloading/unpacking cryptography
  Downloading cryptography-2.1.4.tar.gz (441kB): 441kB downloaded
  Running setup.py (path:/tmp/pip_build_andykw/cryptography/setup.py) egg_info for package cryptography
    error in cryptography setup command: Invalid environment marker: python_version < '3'
    Complete output from command python setup.py egg_info:
    error in cryptography setup command: Invalid environment marker: python_version < '3'

从doc中，它说 Python 2 和 3 支持密码学。然而，这个标记的东西很奇怪。我在互联网上没有找到任何东西。

有任何想法吗？

更新：我的 ubuntu 发行版

Distributor ID: Ubuntu
Description:    Ubuntu 14.04.5 LTS
Release:    14.04
Codename:   trusty

这是我尝试paramiko通过 apt-get安装时所拥有的

[andykw:/home/andykw]$ sudo apt install python3-paramiko
[sudo] password for andykw:
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package python3-paramiko