This page collects information to optimize your notebook setup for an easier work with the DESY computing infrastructure.
1. Single-Sign-On (SSO)
Access to DESY computing resources is protected by your account/password combination. However you don't need to enter your password each and every time you open a fresh connection from your client to a DESY system. All you have to do is to enable Kerberos authentication. You can get passwordless access to the following services once you setup your client correctly:
- ssh to "warp" and "pub" systems
Read and send mail via the DESY Zeuthen mail server
- authenticated access to some kerberos-enabled web servers
On DESY-managed systems this setup is preconfigured.
1.1. Basic configuration
MacOSX systems typically have the Kerberos5 client programs already installed. Linux systems need to install a package typically named "krb5-user" - see the documentation of your distribution to find out.
The system-wide configuration is located in different locatations depending on your client:
- on MacOSX: /Library/Preferences/edu.mit.Kerberos
- on Linux: /etc/krb5.conf
It should look like this for DESY access:
[libdefaults] default_realm = IFH.DE ticket_lifetime = 25h renew_lifetime = 30d forwardable = true noaddresses = true [domain_realm] .ifh.de = IFH.DE .desy.de = DESY.DE
NOTE: Zeuthen (IFH.DE) & Hamburg (DESY.DE) computing resources still reside in independent kerberos realms.
You can now fetch a so called kerberos ticket by issueing kinit <DESY accountname>. You have to enter your DESY password once. See this example:
[notebook] ~ % kinit ahaupt ahaupt@IFH.DE's Password: [notebook] ~ % klist Credentials cache: FILE:/tmp/krb5cc_1000 Principal: ahaupt@IFH.DE Issued Expires Principal May 30 15:49:36 2013 May 31 16:49:36 2013 krbtgt/IFH.DE@IFH.DE
Verify your freshly created ticket with the klist command. Kerberos tickets at DESY have a maximum lifetime of 25 hours for security reasons. However you can renew your tickets passwordless for up to 30 days by invoking kinit -R as long as your original ticket hasn't expired, yet. There are gui programs available for Linux (krb5-auth-dialog) and MacOSX that can do this task automatically in background for you.
1.2. ssh configuration
ssh access to Zeuthen computing resources is available via the warp cluster. Read its documentation for further details. To make your ssh client kerberos-aware, you'll basically need to create/modify the configuration file $HOME/.ssh/config:
Host warp Hostname warp-zeuthen.desy.de GSSAPIAuthentication yes GSSAPIDelegateCredentials yes
GSSAPIAuthentication enables passwordless authentication, GSSAPIDelegateCredentials enables the kerberos ticket forwarding to the ssh server. If you did everything correctly, you should now be able to login without being asked for a password:
[notebook] ~ % ssh warp Last login: Thu May 30 13:22:28 2013 from nomos127.ifh.de Scientific Linux SL release 6.4 (Carbon) Info: http://dvinfo.ifh.de/SL6_User_Information Please report any bugs or problems to email@example.com [elwood-vm4] ~ %