tramp-verbose

tramp-verbose is a variable defined in `tramp.el'.
Its value is

3

Documentation:
Verbosity level for Tramp messages.
Any level x includes messages for all levels 1 .. x-1. The levels are

0 silent (no tramp messages at all)
1 errors
2 warnings
3 connection to remote hosts (default level)
4 activities
5 internal
6 sent and received strings
7 file caching
8 connection properties
9 test commands
10 traces (huge).

You can customize this variable.