도움이 될지 안될지는 모르지만 proftpd.conf파일에서의
 설정부분에 한가지가 제가 설정한 내용과 틀려서...
#MaxInstances 30 
의 부분을 주석을 제거해주세염..

Dos공격을 막기위해 자식프로세스의
 maximum number를 30으로 설정한다.
오직 standalone mode에서만 가능합니다..
proftp가 안되는것과는 상관이 없을것같지만 그래도 한번 설정을
함 해보심이..^^



[김필준]님이 남기신 글:

>
>레드햇에 기본적으로 깔리는 ftp데몬이 wu-ftp잖아요....

>                           그런데 wu-ftp 가 맘에 안들어서.....뭐
 사용자 상위 디렉으로 이동을 제한하는거나 
>                           사용상의 제어가 proftpd 가 편한것
같아서.... 
>
>                           그래서 wu-ftpd를 지우고 proftpd를 깔았는데
이게 불능이네요... 
>                           rpm으로 깔아도 그렇고 소스로 깔아도
그러한데.... 
>                           메세지는 
>                           421 Service not available, remote server has closed
connection 
>                           인데요 서비스를 이용할수 없다 .서버가
접속을 끊었다 인것 같은데요... 
>                           왜 그렇죠??? 
>                           리붓도 여러번해보고 .......... 
>                           proftpd.conf를 나름데로 설정를 해보고
안되서 옆에서 돌아가고 있는 기본으로 
>                           proftpd가 깔리고 잘돌아가는 녀석의 것을
가져다 해보아도 마찮가지 입니다... 
>                           어떻게 해야하는 지요..... 
>                           제발 고수님들의 도움을 바랍네다.....

>
>                           아래에 설정파일 첨부할께요. 
>
>                          
#########################################################################

>                           # # 
>                           # ProFTPD Korea User Groups # 
>                           # http://proftpd.oops.org # 
>                           # # 
>                          
#########################################################################

>                           # ADDED : JoungKyun Kim <admin@oops.org 
>                           # If exist miss configuration, report me to via email

>                          
#########################################################################

>
>                           # This is a basic ProFTPD configuration file (rename it
to 
>                           # 'proftpd.conf' for actual use. It establishes a single
server 
>                           # and a single anonymous login. It assumes that you have
a user/group 
>                           # "nobody" and "ftp" for normal
operation and anon. 
>
>                           ServerName "ProFTPD For Korean" 
>
>                           # Determined Server operation mode 
>                           ServerType standalone 
>                           #ServerType inetd 
>                           DefaultServer on 
>                           ServerAdmin feel73@yahoo.co.kr 
>
>                           # This directive is set CHROOT for account 
>                           #DefaultRoot ~ !groupname 
>
>                           # permit to login root permisstion. If you are using PAM
module, 
>                           # first delete root line from ftpusers file 
>                           RootLogin off 
>
>                           # Port 21 is the standard FTP port. If select Server
operation mode 
>                           # "standalone", U must delete hash mark(#)
from Port line. 
>                           # Else if select Server operation mode
"inetd", you must config port 
>                           # number in /etc/services 
>                           # 
>                           Port 21 
>
>
>                           # Umask 022 is a good standard umask to prevent new dirs
and files 
>                           # from being group and world writable. 
>                           Umask 022 
>
>                           # Use Pam Module (required /etc/pam.d/ftp) 
>                           # please read /usr/doc/proftpd-version/README.PAM

>                           # 
>                           AuthPAMAuthoritative on 
>
>                           # Time that start time of end time of ftp service. This
value 
>                           # is followed 24 time format 
>                           # 
>                           # UpTime 10 
>                           # DownTime 23 
>
>                           # Deny glob() dos attack before verson 1.2.1

>                           DenyFilter \*.*/ 
>
>
>                           # Config some access time. After some seconds that user
has no action, 
>                           # connection is closed. ( 0 is unlimited ) 
>                           TimeoutIdle 600 
>                           TimeoutNoTransfer 600 
>                           TimeoutLogin 0 
>
>                           # DeferWelcome prevents proftpd from displaying the
servername 
>                           # until a client has authenticated. 
>                           DeferWelcome off 
>
>                           # We want 'welcome.msg' displayed at login, and
'.message' displayed 
>                           # in each newly chdired directory. 
>                           DisplayLogin /etc/proftpd/conf/welcome.msg 
>                           DisplayFirstChdir .message 
>
>                           # To prevent DoS attacks, set the maximum number of
child processes 
>                           # to 30. If you need to allow more than 30 concurrent
connections 
>                           # at once, simply increase this value. Note that this
ONLY works 
>                           # in standalone mode, in inetd mode you should use an
inetd server 
>                           # that allows you to limit maximum number of processes
per service 
>                           # (such as xinetd) 
>                           #MaxInstances 30 
>
>                           # Set the user and group that the server normally runs
at. 
>                           User nobody 
>                           Group nobody 
>
>                           # Support upload/download ratios 
>                           # please read /usr/doc/proftpd-version/mod_ratio.c

>                           # 
>                           # Ratios on 
>                           # HostRatio foobar.net 100 10 5 100000 
>
>                           # Normally, we want files to be overwriteable.

>
>                           AllowOverwrite on 
>
>
>                           # Show the dot(hidden) files 
>                           # LsDefaultOptions "-a" 
>
>                           # A basic anonymous configuration, no upload
directories. 
>
>                           User ftp 
>                           Group ftp 
>                           RequireValidShell off 
>
>                           # AnonRequirePassword on 
>                           # ShowSymlinks off 
>
>                           # We want clients to be able to login with
"anonymous" as well as "ftp" 
>                           UserAlias anonymous ftp 
>
>                           # Limit the maximum number of anonymous logins

>                           MaxClients 10 
>
>                           # The MaxClientsPerHost directive configures the maximum
number of clients 
>                           # allowed to connect per host. The optional argument
message may be used 
>                           # which will be displayed to a client attempting to
exceed the maximum 
>                           # value. If message is not supplied, a system-wide
default message is used. 
>                           MaxClientsPerHost 3 "Sorry, 3 connection allow per
one host" 
>
>                           # maximum number of authenticated clients that can log
into the server for 
>                           # any given user. 
>                           MaxHostsPerUser 1 "Sorry, 1 connection allow per
one user name" 
>
>                           # hide files that possess follow owner and group_owner

>                           #HideUser root 
>                           #HideGroup root 
>
>                           # Restricted bandwidth. this value is set byte.

>                           #RateReadBPS 256 
>                           #RateReadFreeBytes 5120 
>                           #RateReadHardBPS on 
>
>                           # We want 'welcome.msg' displayed at login, and
'.message' displayed 
>                           # in each newly chdired directory. 
>                           DisplayLogin welcome.msg 
>                           DisplayFirstChdir .message 
>
>                           # Limit WRITE everywhere in the anonymous chroot

>
>                           DenyAll 
>
>
>                           # Upload directory, allow upload and mkdir, deny
download. 
>                           # 
>                           # 
>                           # 
>                           # DenyALL 
>                           # 
>                           # 
>                           # AllowALL 
>                           # 
>                           # 

========================================