SSH connections of older clients/servers

A configuration change was automatically put into production Tuesday morning which had been prepared the previous day on Ubuntu 14_04 LTS, Ubuntu 16_04 LTS and Ubuntu 18_04 LTS in order to increase the level of security of SSH connections within FNWI. The change had the side effect of crashing the SSH daemon on Ubuntu 12_04 LTS and preventing older SSH clients from connecting at all. Users are encouraged to update their SSH clients so that we can gradually increase the level of security again.