SRE/Dc-operations/Platform-specific documentation/Opengear Serial Consoles

From Wikitech
  • We use the Opengear CM4148. This is the 48 port version of the serial console server.
  • It is just easier to get the maximum port model than juggle various models per datacenter deployment.
  • As a matter of course, we attach all network devices, and all power strips to the serial console in each deployment.
  • Please note caching deployments don't offer connections to power strips, only full deployment sites.

Using the Serial Console

  • SSH into the serial console in question.
  • Our naming standard depends on deployment.
  • Full deployments are scs-$rack-$site.mgmt.$site.wmnet
  • noting the rack location when we have multiple racks is just easier on folks.
  • Caching deployments are scs-$site.mgmt.$site.wmnet
  • Since caching sites usually are less than 5 racks and won't ever need more than a single serial console.
  • Once on opengear CLI, type in pmshell and hit enter.
  • All the setup ports with labels of what they are connected to will be listed, and you can enter the number of the port you wish to connect to.
  • If you already know the port # you can simply connect with pmshell port##

Administrative Actions

  • All of the actions listed below require the HTTPS web console, not the command line via SSH.

Initial Setup

  • This is done by the on-site technician for the datacenter deployment.
  • Set up your local laptop to use IP addresses within the 192.168.0.X range (leave open, as the opengear defaults to that) with a subnet mask of and no gateway.
    • No gateway ensures your wifi connection to internet/irc/whatever remains active and primary for that traffic.
  • Plug your laptop's network connection into the LAN port on the serial console server.
  • Open the serial console web configuration via [1]
    • You will have to accept the console's self signed certificate.
  • Login with the default user name root & the default password default
  • Upgrade the OS to the latest recommended version
  • Update the console's host name under System > Administration.
  • Update the console's password to our mgmt password under System > Administration.
  • Set the systems network settings under System > IP.
    • The information for the network settings should be attached to the setup ticket for the console in RT.
  • System: IP
    • DNS:
  • System: time
    • Timezone -> UTC
    • Enable NTP -> checked
    • NTP Server List:;
  • Alerts & Logging: SNMP
    • Enable -> check
    • Location -> one of: eqiad;codfw;ulsfo;etc;etc
    • Contact ->
    • Read-Only Community -> SNMP secret
  • Serial & Network: Users
    • Add user:
      •   description -> rancid
      •   username -> rancid
      •   Disable Password Authentication -> check
      •   Groups -> admin
      •   Password -> generate long random string
      •   New ssh key -> rancid SSH pub key
      • Serial & Network: Authentication Configuration
      •   CLI Management Session Timeout -> 60
  • Status: Syslog:
    •   Syslog Server Address -> syslog.anycast.wmnet
  • System: services
    • Enable Telnet command shell -> uncheck
    • Enable LLDP/CDP service -> check
    • NTP Server -> verify check
    • SNMP daemon -> verify check
  • All basic networking and login should now be set. All that is left is to setup individual ports, outlined below.
  • Add device to monitoring
    • LibreNMS (
    • Rancid
    • Icinga

Port / Connection Setup

  • The SCS exists on the management network, to connect to it, you must be attached to the mgmt network by physical link, or proxy.
  • Once logged in, click on Serial & Network > Serial Port
    • This lists all ports, and their labels.
  • Click Edit for the specific port, and set the port details.
    • The name must be set (or it won't show in pmshell command from cli), the ports default connection settings (no logging, 9600-8-N-1, no flow control) are appropriate for the majority of our network gear and power strips.
  • Apply/Save and the port is now setup.

Escape sequence


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