title: Why is a shell within a docker container showing dmesg content from the host?
body: <p>I have a docker container running Debian jessie on Ubuntu yakkety.</p>
  
  <p>When within the docker (connected via <code>ssh</code> for instance) I am isolated from the host (which is expected). I however realized that <code>dmesg</code> shows me the messages for the host and not for the container. <strong>How can it have access to information of its host?</strong></p>
  
  <p>The configuration of the docker container is not special (except that it uses a specific bridge, different from <code>docker0</code>), in particular it does not run in any privileged mode (<code>"Privileged": false</code> below):</p>
  
  <pre><code>root@srv ~# docker inspect minecraft-1-8
  [
      {
          "Id": "748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e",
          "Created": "2016-12-01T15:35:05.287672787Z",
          "Path": "/usr/bin/supervisord",
          "Args": [],
          "State": {
              "Status": "running",
              "Running": true,
              "Paused": false,
              "Restarting": false,
              "OOMKilled": false,
              "Dead": false,
              "Pid": 28650,
              "ExitCode": 0,
              "Error": "",
              "StartedAt": "2016-12-15T18:37:08.409564695Z",
              "FinishedAt": "2016-12-15T18:37:07.457274028Z"
          },
          "Image": "sha256:78a2f88d47e29523503c2196ed2faaa3d1039d948d73987edc03b2abd338595d",
          "ResolvConfPath": "/var/lib/docker/containers/748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e/resolv.conf",
          "HostnamePath": "/var/lib/docker/containers/748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e/hostname",
          "HostsPath": "/var/lib/docker/containers/748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e/hosts",
          "LogPath": "/var/lib/docker/containers/748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e/748cfdfbf3fb5526cb7151cbc0857117af3c7bd8ab9e086c4f2efb897290d66e-json.log",
          "Name": "/minecraft-1-8",
          "RestartCount": 0,
          "Driver": "overlay",
          "MountLabel": "",
          "ProcessLabel": "",
          "AppArmorProfile": "",
          "ExecIDs": null,
          "HostConfig": {
              "Binds": null,
              "ContainerIDFile": "",
              "LogConfig": {
                  "Type": "json-file",
                  "Config": {}
              },
              "NetworkMode": "docker",
              "PortBindings": {},
              "RestartPolicy": {
                  "Name": "no",
                  "MaximumRetryCount": 0
              },
              "AutoRemove": false,
              "VolumeDriver": "",
              "VolumesFrom": null,
              "CapAdd": null,
              "CapDrop": null,
              "Dns": [],
              "DnsOptions": [],
              "DnsSearch": [],
              "ExtraHosts": null,
              "GroupAdd": null,
              "IpcMode": "",
              "Cgroup": "",
              "Links": null,
              "OomScoreAdj": 0,
              "PidMode": "",
              "Privileged": false,
              "PublishAllPorts": false,
              "ReadonlyRootfs": false,
              "SecurityOpt": null,
              "UTSMode": "",
              "UsernsMode": "",
              "ShmSize": 67108864,
              "Runtime": "runc",
              "ConsoleSize": [
                  0,
                  0
              ],
              "Isolation": "",
              "CpuShares": 0,
              "Memory": 0,
              "CgroupParent": "",
              "BlkioWeight": 0,
              "BlkioWeightDevice": null,
              "BlkioDeviceReadBps": null,
              "BlkioDeviceWriteBps": null,
              "BlkioDeviceReadIOps": null,
              "BlkioDeviceWriteIOps": null,
              "CpuPeriod": 0,
              "CpuQuota": 0,
              "CpusetCpus": "",
              "CpusetMems": "",
              "Devices": [],
              "DiskQuota": 0,
              "KernelMemory": 0,
              "MemoryReservation": 0,
              "MemorySwap": 0,
              "MemorySwappiness": -1,
              "OomKillDisable": false,
              "PidsLimit": 0,
              "Ulimits": null,
              "CpuCount": 0,
              "CpuPercent": 0,
              "IOMaximumIOps": 0,
              "IOMaximumBandwidth": 0
          },
          "GraphDriver": {
              "Name": "overlay",
              "Data": {
                  "LowerDir": "/var/lib/docker/overlay/e78ce9dbcedd6974429a4aada8f38913b7d35da41f586f203dd99a568f38b6c3/root",
                  "MergedDir": "/var/lib/docker/overlay/e8422e4707d95db8ea747af2367626cc8bf16e95f8eb05dfad9a63461c9ade86/merged",
                  "UpperDir": "/var/lib/docker/overlay/e8422e4707d95db8ea747af2367626cc8bf16e95f8eb05dfad9a63461c9ade86/upper",
                  "WorkDir": "/var/lib/docker/overlay/e8422e4707d95db8ea747af2367626cc8bf16e95f8eb05dfad9a63461c9ade86/work"
              }
          },
          "Mounts": [],
          "Config": {
              "Hostname": "minecraft-1-8",
              "Domainname": "",
              "User": "",
              "AttachStdin": false,
              "AttachStdout": true,
              "AttachStderr": true,
              "Tty": false,
              "OpenStdin": false,
              "StdinOnce": false,
              "Env": [
                  "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
              ],
              "Cmd": [
                  "/usr/bin/supervisord"
              ],
              "Image": "minecraft",
              "Volumes": null,
              "WorkingDir": "",
              "Entrypoint": null,
              "OnBuild": null,
              "Labels": {}
          },
          "NetworkSettings": {
              "Bridge": "",
              "SandboxID": "cf411634babad31138ab4572b9cd7306f74a54dd1baf4cd8d7706d7e7020c594",
              "HairpinMode": false,
              "LinkLocalIPv6Address": "",
              "LinkLocalIPv6PrefixLen": 0,
              "Ports": {},
              "SandboxKey": "/var/run/docker/netns/cf411634baba",
              "SecondaryIPAddresses": null,
              "SecondaryIPv6Addresses": null,
              "EndpointID": "",
              "Gateway": "",
              "GlobalIPv6Address": "",
              "GlobalIPv6PrefixLen": 0,
              "IPAddress": "",
              "IPPrefixLen": 0,
              "IPv6Gateway": "",
              "MacAddress": "",
              "Networks": {
                  "docker": {
                      "IPAMConfig": {
                          "IPv4Address": "10.200.0.100"
                      },
                      "Links": null,
                      "Aliases": [
                          "748cfdfbf3fb"
                      ],
                      "NetworkID": "7b20560b36032d36ffe6c0ebece6b4408355d207f4e203a2957b0434ee0afdc1",
                      "EndpointID": "9fa4fc914dfe76022ce0db02e48a7e7c85c57bc2a15b0b3e5d81b1f24d95f376",
                      "Gateway": "10.200.0.1",
                      "IPAddress": "10.200.0.100",
                      "IPPrefixLen": 24,
                      "IPv6Gateway": "",
                      "GlobalIPv6Address": "",
                      "GlobalIPv6PrefixLen": 0,
                      "MacAddress": "02:42:0a:c8:00:64"
                  }
              }
          }
      }
  ]
  </code></pre>