usermax:x:1004:1005::/home/usermax:
usermax:x:1004:1005:,,,:/home/usermax:/bin/bash
/etc/vsftpd.conf
listen=YES
listen_ipv6=NO
anonymous_enable=NO
local_enable=YES
write_enable=YES
chroot_local_user=YES
local_umask=022
force_dot_files=YES
chroot_local_user=YES
chroot_list_enable=YES
chroot_list_file=/etc/vsftpd.chroot_list
15 -> 1*5=5
16 -> 1*6=6
...
24 -> 2*4=8