Настраивал proftpd+mysql, всё работало нормально. Как ввёл вритхосты, так перестали авторизироваться пользователи, которые находятся в mysql, толкьо реальные, заведённые в системе, могут авторизироваться и анонимусы.
slackware 10.1, proftpd 1.3.0rc2.

proftpd.conf:

ServerName                      "some company FTP Server"
ServerType                      standalone
DefaultServer                   on
ServerIdent                     on "Welcome to the some company  FTP server. Please login..."

UseReverseDNS                   off
IdentLookups                    off

TimeoutLogin                    120
TimeoutIdle                     600
TimeoutNoTransfer               900
TimeoutStalled                  3600
Port                            21
Umask                           022
MaxInstances                    100

User                            nobody
Group                           nogroup

AllowOverwrite          on

<Limit SITE_CHMOD>
  DenyAll
</Limit>

RootLogin off
RequireValidShell off

TransferLog             /usr/local/proftpd/var/transfer.log
ExtendedLog             /usr/local/proftpd/var/access.log WRITE,READ write
ExtendedLog             /usr/local/proftpd/var/debug.log ALL

###### our FTP server
<VirtualHost 10.0.0.4>
  ServerName                    "DigiLan FTP Server"
  ServerIdent                   on "Welcome to the DigiLan FTP server. Please login..."
  MaxClients                    30
  MaxLoginAttempts              2
  DeferWelcome                  on
  DefaultRoot ~

    # The passwords in MySQL are encrypted using CRYPT
    SQLAuthTypes            Plaintext Crypt
    SQLAuthenticate         users* groups*
    SQLConnectInfo  ftpdb@192.168.100.3 ftpuser ftppass
    SQLUserInfo     ftpuser userid passwd uid gid homedir shell
    SQLGroupInfo    ftpgroup groupname gid members
    SQLMinID        500
    SQLHomedirOnDemand on
    SQLLog PASS updatecount
    SQLNamedQuery updatecount UPDATE "count=count+1, accessed=now() WHERE userid='%u'" ftpuser
    SQLLog  STOR,DELE modified
    SQLNamedQuery modified UPDATE "modified=now() WHERE userid='%u'" ftpuser

    # User quotas
    # ===========
    QuotaEngine on
    QuotaDirectoryTally on
    QuotaDisplayUnits Mb
    QuotaShowQuotas on
    SQLNamedQuery get-quota-limit SELECT "name, quota_type, per_session, limit_type, bytes_in_avail, bytes_out_avail, bytes_xfer_avail, files_in_avail, files_out_avail, files_xfer_avail FROM ftpquotalimits WHERE name = '%{0}' AND quota_type = '%{1}'"
    SQLNamedQuery get-quota-tally SELECT "name, quota_type, bytes_in_used, bytes_out_used, bytes_xfer_used, files_in_used, files_out_used, files_xfer_used FROM ftpquotatallies WHERE name = '%{0}' AND quota_type = '%{1}'"
    SQLNamedQuery update-quota-tally UPDATE "bytes_in_used = bytes_in_used + %{0}, bytes_out_used = bytes_out_used + %{1}, bytes_xfer_used = bytes_xfer_used + %{2}, files_in_used = files_in_used + %{3}, files_out_used = files_out_used + %{4}, files_xfer_used = files_xfer_used + %{5} WHERE name = '%{6}' AND quota_type = '%{7}'" ftpquotatallies
    SQLNamedQuery insert-quota-tally INSERT "%{0}, %{1}, %{2}, %{3}, %{4}, %{5}, %{6}, %{7}" ftpquotatallies

    QuotaLimitTable sql:/get-quota-limit
    QuotaTallyTable sql:/get-quota-tally/update-quota-tally/insert-quota-tally

  <Anonymous ~ftp>
    MaxClientsPerHost                   3
    User                                ftp
    Group                               ftp
    UserAlias                   anonymous ftp
    MaxClients                  40
    DisplayLogin                welcome.msg
    DisplayFirstChdir           .message
    AuthAliasOnly on

    <Limit WRITE>
      DenyAll
    </Limit>

    <Directory "/ftp/files/incoming">
      <Limit WRITE>
        AllowAll
      </Limit>
    </Directory>
  </Anonymous>

</Virtualhost>

######## Internet server
<VirtualHost 1.2.3.4>
  ServerName                    "some company  FTP Server"
  ServerIdent                   on "Welcome to the some company FTP server."
  DefaultRoot ~

  <Limit LOGIN>
    DenyAll
  </Limit>

  <Anonymous /ftp/users>
    MaxClientsPerHost 3
    User                                ftp
    Group                               ftp
    HideNoAccess                        on
    MaxClients                  30

    UserAlias                   anonymous ftp
    MaxClients                  40
    DisplayLogin                welcome.msg
    DisplayFirstChdir           .message

    AuthAliasOnly on

    <Limit LOGIN>
      AllowAll
    </Limit>

    <Limit WRITE>
      DenyAll
    </Limit>

    <Directory "/ftp/users">
      TransferRate RETR 32
    </Directory>

  </Anonymous>
</VirtualHost>

• proftpd+virtual+mysql,Assorted, 15:22 , 07-Дек-05

сорри. нашёл грабли.
в виртхостах не стояло RequireValidShell off
а шеллы кривые все были :)