SSH: The escape character (default ~)is only recognized at the beginning of a line. '~.' --close connection, ~~ --send '~', ~C-Z --suspend

GNU screen: C-A G ----disables audible bell.

I did not understand that visual bell is a 'feature'. I thought it was a bug. It was the only reason why I did not make a full use of GNU Screen. Now I know.
In xterm the default should be no visual bell. However, you can use `xterm +vb` to explicitely disable it.
In my case visual bell was enabled in /etc/screenrc.
What is interesting, is that any user changes behaviour of all users, of the whole system.

An analogy of MS/Apple/Linux users came to my mind. Its like wearing clothes. Windows is a warehouse, noname. Mac is a brand like Stones, D&G, Kevin K

lein. Linux is a radioshack. It is a source code. It is materilal from which you can build your own style. Every linux user is different.
Yet another analogy. Cooking food. Mac is a restaurant, Win is junk food (McDonalds), Linux is cook at home (including 'heat this in microwave oven for 3 min and eat').

The word 'linux' can be substituted by {Open,Free,Net,DragonFly}BSD or any other open source project.

less: ESC-u ---syntax highlighting on/off switcher

sniffit -p25 -t machine2 ----hoeren komplette Mailverkehr eines Rechners (Port 25) namens machine2 ab.