Whilst usernames at Leeds and Sheffield are the same as each other, they are different from those at York.
The passwords at all the sites may be different.
If you wish to have a consistent login at all sites that this is possible with gsi-ssh which uses an e-Science Digital Certificate. See the HowTo documentation for details on use.
jdk 1.6.0_45 and jdk-1.7.0_21 available
