LXC container support without LXD (#552)

* LXC container support without LXD

* Fix: LXC required root privilege

* Update README

README.md

@@ -81,9 +81,10 @@ Table of Contents
       * [Example: Scan specific servers](#example-scan-specific-servers)
       * [Example: Scan via shell instead of SSH.](#example-scan-via-shell-instead-of-ssh)
          * [cron](#cron)
-      * [Example: Scan containers (Docker/LXD)](#example-scan-containers-dockerlxd)
+      * [Example: Scan containers (Docker/LXD/LXC)](#example-scan-containers-dockerlxdlxc)
          * [Docker](#docker)
          * [LXD](#lxd)
+	 * [LXC](#lxc)
    * [Usage: Report](#usage-report)
       * [How to read a report](#how-to-read-a-report)
          * [Example](#example-1)
@@ -747,7 +748,7 @@ host         = "172.31.4.82"
 #    ["key", "value"],
 #]
 #[servers.172-31-4-82.containers]
-#type = "lxd" # or "docker"
+#type = "lxd" # or "docker" or "lxc"
 #includes = ["${running}"]
 #excludes = ["container_name", "container_id"]
 ```
@@ -852,7 +853,7 @@ You can customize your configuration using this template.
     #    ["key", "value"],
     #]
     #[servers.172-31-4-82.containers]
-    #type = "lxd" # or "docker"
+    #type = "lxd" # or "docker" or "lxc"
     #includes = ["${running}"]
     #excludes = ["container_name", "container_id"]
     ```
@@ -867,7 +868,7 @@ You can customize your configuration using this template.
     - cpeNames: see [Usage: Scan vulnerability of non-OS package](#usage-scan-vulnerability-of-non-os-package)
     - ignoreCves: CVE IDs that will not be reported. But output to JSON file.
     - optional: Add additional information to JSON report.
-    - containers: see [Example: Scan containers (Docker/LXD)(#example-scan-containers-dockerlxd)
+    - containers: see [Example: Scan containers (Docker/LXD/LXC)(#example-scan-containers-dockerlxdlxc)
 
     Vuls supports two types of SSH. One is external command. The other is native go implementation. For details, see [-ssh-native-insecure option](#-ssh-native-insecure-option)
 
@@ -1108,7 +1109,7 @@ If you use local scan mode for cron jobs, don't forget to add below line to `/et
 Defaults:vuls !requiretty
 ```
 
-## Example: Scan containers (Docker/LXD)
+## Example: Scan containers (Docker/LXD/LXC)
 
 It is common that keep containers running without SSHd daemon.  
 see [Docker Blog:Why you don't need to run SSHd in your Docker containers](https://blog.docker.com/2014/06/why-you-dont-need-to-run-sshd-in-docker/)
@@ -1182,6 +1183,30 @@ type = "lxd"
 includes = ["${running}"]
 ```
 
+### LXC
+
+Vuls scans lxc via `lxc-attach` instead of SSH.  
+```
+[servers]
+
+[servers.172-31-4-82]
+host         = "172.31.4.82"
+user        = "ec2-user"
+keyPath     = "/home/username/.ssh/id_rsa"
+
+[servers.172-31-4-82.containers]
+type = "lxc"
+includes = ["${running}"]
+```
+
+LXC required root privilege.  
+
+Example of /etc/sudoers on target servers
+
+```
+vuls ALL=(ALL) NOPASSWD:/usr/bin/lxc-attach -n *, /usr/bin/lxc-ls *
+```
+
 ----
 
 # Usage: Report