Thx Tim for help.

Now I'm using another user than root...
But I'm still in a black hole (+headache), sadly without finding any document about how using this "go" software + obfs4 :'(

Sooory, I'm not really nice with source compiling... :s


go help gopath :
[...]
Each directory listed in GOPATH must have a prescribed structure:

The src/ directory holds source code.  The path below 'src'
determines the import path or executable name.

The pkg/ directory holds installed package objects.
As in the Go tree, each target operating system and
architecture pair has its own subdirectory of pkg
(pkg/GOOS_GOARCH).
[...]

But I don't see any /src or /pkg in the downloaded git folder ?

Here the content downloaded :
$ dir -R /home/petrusko/obfs4/

obfs4/:
ChangeLog  common  doc    LICENSE  obfs4proxy  README.md    transports

obfs4/common:
csrand    drbg  log  ntor  probdist  replayfilter  socks5  uniformdh

obfs4/common/csrand:
csrand.go

obfs4/common/drbg:
hash_drbg.go

obfs4/common/log:
log.go

obfs4/common/ntor:
ntor.go  ntor_test.go

obfs4/common/probdist:
weighted_dist.go  weighted_dist_test.go

obfs4/common/replayfilter:
replay_filter.go  replay_filter_test.go

obfs4/common/socks5:
args.go  args_test.go  rfc1929.go  socks5.go  socks_test.go

obfs4/common/uniformdh:
uniformdh.go  uniformdh_test.go

obfs4/doc:
obfs4proxy.1  obfs4-spec.txt

obfs4/obfs4proxy:
obfs4proxy.go  proxy_http.go  proxy_socks4.go  pt_extras.go  termmon.go  termmon_linux.go

obfs4/transports:
base  meeklite    obfs2  obfs3  obfs4  scramblesuit  transports.go

obfs4/transports/base:
base.go

obfs4/transports/meeklite:
base.go  meek.go

obfs4/transports/obfs2:
obfs2.go

obfs4/transports/obfs3:
obfs3.go

obfs4/transports/obfs4:
framing  handshake_ntor.go  handshake_ntor_test.go  obfs4.go  packet.go  statefile.go

obfs4/transports/obfs4/framing:
framing.go  framing_test.go

obfs4/transports/scramblesuit:
base.go  conn.go  handshake_ticket.go  handshake_uniformdh.go  hkdf_expand.go