Installing and Maintaining GSI OpenSSH¶
This document is for software that will no longer be supported after the OSG 3.5 retirement (February 2022). See the Release Series Support Policy for details.
This document contains instructions to install and configure the GSI OpenSSH server available in the OSG repository for use on your cluster.
Before starting the installation process, consider the following points (consulting the Reference section below as needed):
- User IDs: If they do not exist already, the installation will create the Linux users
As with all OSG software installations, there are some one-time (per host) steps to prepare in advance:
- Ensure the host has a supported operating system
- Obtain root access to the host
- Prepare the required Yum repositories
- Install CA certificates
Installing GSI OpenSSH¶
Install the GSI OpenSSH rpms:
[email protected] # yum install gsi-openssh-server gsi-openssh-clients
Configuring GSI OpenSSH¶
In order to get a running instance of the GSI OpenSSH server, you'll need to change the default configuration.
However, before you go any further, you'll need to decide whether you want GSI OpenSSH to be your primary ssh service or
not (e.g. whether the GSI OpenSSH service will replace your existing SSH service).
Regardless of your choice, you should probably have both services use the same host keys.
This can be done by running the following commands :
[email protected] # cd /etc/gsissh [email protected] # ln -s /etc/ssh/ssh_host_rsa_key ssh_host_rsa_key [email protected] # ln -s /etc/ssh/ssh_host_rsa_key.pub ssh_host_rsa_key.pub [email protected] # ln -s /etc/ssh/ssh_host_dsa_key ssh_host_dsa_key [email protected] # ln -s /etc/ssh/ssh_host_dsa_key.pub ssh_host_dsa_key.pub [email protected] # ln -s /etc/ssh/ssh_host_ecdsa_key ssh_host_ecdsa_key [email protected] # ln -s /etc/ssh/ssh_host_ecdsa_key.pub ssh_host_ecdsa_key.pub [email protected] # ln -s /etc/ssh/ssh_host_ed25519_key ssh_host_ed25519_key [email protected] # ln -s /etc/ssh/ssh_host_ed25519_key.pub ssh_host_ed25519_key.pub
Your system may not have all of these host keys
If you choose not to replace your existing SSH service, you'll need to change the port setting in the GSI OpenSSH
configuration to another port (e.g. 2222) so that you can run both SSH services at the same time.
This can be done by editing
/etc/gsissh/sshd and setting
Regardless of the authorization method used for the user, any
account that will be used with GSI OpenSSH must have a shell
assigned to it and not be locked (e.g., have
! in the password field of
To configure authentication for GSI OpenSSH, follow the instructions in the LCMAPS VOMS plugin document to prepare the LCMAPS VOMS plugin.
Using GSI OpenSSH¶
The following table gives the commands needed to start, stop, enable, and disable GSI OpenSSH.
|To...||Run the command...|
|Start the service||
|Stop the service||
|Enable the service to start on boot||
|Disable the service from starting on boot||
Validating GSI OpenSSH¶
After starting the
gsisshd service you can check if it is running correctly
[email protected] $ grid-proxy-init Your identity: /DC=ch/DC=cern/OU=Organic Units/OU=Users/CN=User Name Enter GRID pass phrase for this identity: Creating proxy ............................................................................................... Done Your proxy is valid until: Sat Apr 23 08:18:27 2016 $ gsissh localhost -p 2222 Last login: Tue Sep 18 16:08:03 2012 from itb4.uchicago.edu $
You can get information on troubleshooting errors on the NCSA page.
To troubleshoot LCMAPS authorization, you can add the following to
/etc/sysconfig/gsisshd and choose a higher debug
# level 0: no messages, 1: errors, 2: also warnings, 3: also notices, # 4: also info, 5: maximum debug LCMAPS_DEBUG_LEVEL=2
Output goes to
journalctl by default.
To get assistance please use this Help Procedure.
Useful configuration and log files¶
|Service or Process||Configuration File||Description|
||Environment variables for gsisshd|
|Service or Process||Log File||Description|
||All log messages|
|Service or Process||File||Description|
||X.509 host key|
||RSA Host key|