ftp 500 OOPS: could not bind listening IPv4 socket

root@xiuhua:~# ftp IP
Connected to *.*.*.*.
500 OOPS: could not bind listening IPv4 socket
ftp> exit
root@xiuhua:~# netstat -anp | grep 21tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN      1112/xinetd
tcp        0      0 10.239.50.15:21         10.239.50.15:55209      TIME_WAIT   -
unix  2      [ ACC ]     STREAM     LISTENING     9421     1172/avahi-daemon:  /var/run/avahi-daemon/socket
unix  3      [ ]         STREAM     CONNECTED     9521     1352/upowerd
unix  3      [ ]         STREAM     CONNECTED     6921     1325/dbus-daemon    @/tmp/dbus-WMSDo9JReq
unix  3      [ ]         STREAM     CONNECTED     9452     1221/accounts-daemo
unix  3      [ ]         STREAM     CONNECTED     7911     1221/accounts-daemo
貌似xinetd 占用了21 进程

root@xiuhua:~# service xinetd stop

root@xiuhua:~# service vsftpd start
vsftpd start/running, process 2046
root@xiuhua:~# netstat -anp | grep 21
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN      2046/vsftpd
unix  2      [ ACC ]     STREAM     LISTENING     9421     1172/avahi-daemon:  /var/run/avahi-daemon/socket
unix  3      [ ]         STREAM     CONNECTED     9521     1352/upowerd
unix  3      [ ]         STREAM     CONNECTED     6921     1325/dbus-daemon    @/tmp/dbus-WMSDo9JReq
unix  3      [ ]         STREAM     CONNECTED     9452     1221/accounts-daemo
unix  3      [ ]         STREAM     CONNECTED     7911     1221/accounts-daemo

root@xiuhua:/home/ftp# ftp 10.239.50.15
Connected to 10.239.50.15.
220 (vsFTPd 2.3.2)
Name (10.239.50.15:root): xiuhua
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>