issue solved : better later than never 
ok loggin as root under /etc and checking ftpfiles ,passwd and shadow ones
comparing to other networkedoxes seem my ftpacces is corrupted , ls -al ftpacces & consulting by vi command confirmes the case :
ls -al ftpaccess
-rw-rw-rw- 1 root other 94 May 10 10:33 ftp access
vi shown :
ld.so-1.7.0ss_dns.so.1passive ports 0.0.0.0/0 10000 10499
passive ports 0.0.0.0/0 10000 10499
~
~
"perso" 2L, 94C
1-i rename the wrong ftpaccess perso.
2-a reverse ftp to an oxe with same release and a good ftpaccess .
3- putting the new file under /etc and moving the old one "perso " to tmpd.
i see permission and owner has changed comparing to original a ftp connection test return connected .
to be sure reboot is called after system start up permission and owner are good also ftp works .
-rw-rw-rw- 1 root other 520 May 17 15:47 ftpaccess
> ftp 10.235.96.135
Connected to LFr_cpu20.
220 LFr_cpu20 FTP server () ready.
Name (10.235.96.135:mtcl): mtcl
331 Password required for mtcl.
Password:
230 User mtcl logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>
