//我使用的Ubuntu版本：19.10
Ubuntu自帶了一個FTP服務器，叫做vsftpd (Very Safe FTP)，安裝起來很方便，所以這里我將使用vsftpd來作演示。
STEP 1：安裝vsftpd
sudo apt update sudo apt install vsftpd
STEP 2：新建FTP專用用戶
如果想要給FTP服務器設置用戶名和密碼，就需要新建一個用戶。FTP的登陸賬號和密碼就是該用戶的賬號和密碼。
一個FTP服務器可以有多個賬號，不同賬號的訪問權限還可以不一樣。
//注：其實並不是必須新建一個FTP專用的用戶，可以使用已有的用戶。但是這樣會造成很大的安全隱患，所以不建議這么做。
創建用戶文件夾：
sudo mkdir /home/EFtp
這是用戶文件夾，以后還會用來存儲FTP服務器的文件。文件夾的名字應與用戶名保持一致。
//注：我的FTP用戶名是EFtp，這個名字可以按照個人喜好設置，沒必要跟我的一樣。如果要使用你自己的用戶名，請把本教程的所有EFtp改成你自己的用戶名（已經被我用紅色勾了出來）。
設置文件夾權限：
sudo chmod 777 -R /home/EFtp
777：開啟全部權限。
-R：將子文件和子文件夾一同設置。
創建用戶：
sudo useradd -d /home/EFtp -m EFtp
-d：設置用戶文件夾
-m：設置用戶名
設置密碼：
sudo passwd EFtp
然后根據提示設置密碼。
注意，輸入密碼的過程中，密碼不會顯示出來。
STEP 3：配置vsftpd
打開配置文件：
sudo vim /etc/vsftpd.conf
更改為這樣（需要注意的行用綠色表示了出來）：
1 # Example config file /etc/vsftpd.conf 2 # 3 # The default compiled in settings are fairly paranoid. This sample file 4 # loosens things up a bit, to make the ftp daemon more usable. 5 # Please see vsftpd.conf.5 for all compiled in defaults. 6 # 7 # READ THIS: This example file is NOT an exhaustive list of vsftpd options. 8 # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's 9 # capabilities. 10 # 11 # 12 # Run standalone? vsftpd can run either from an inetd or as a standalone 13 # daemon started from an initscript. 14 listen=NO 15 # 16 # This directive enables listening on IPv6 sockets. By default, listening 17 # on the IPv6 "any" address (::) will accept connections from both IPv6 18 # and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6 19 # sockets. If you want that (perhaps because you want to listen on specific 20 # addresses) then you must run two copies of vsftpd with two configuration 21 # files. 22 listen_ipv6=YES 23 # 24 # Allow anonymous FTP? (Disabled by default). 25 anonymous_enable=NO 26 # 27 # Uncomment this to allow local users to log in. 28 local_enable=YES 29 # 30 # Uncomment this to enable any form of FTP write command. 31 write_enable=YES 32 # 33 # Default umask for local users is 077. You may wish to change this to 022, 34 # if your users expect that (022 is used by most other ftpd's) 35 #local_umask=002 36 # 37 # Uncomment this to allow the anonymous FTP user to upload files. This only 38 # has an effect if the above global write enable is activated. Also, you wil l 39 # obviously need to create a directory writable by the FTP user. 40 #anon_upload_enable=YES 41 # 42 # Uncomment this if you want the anonymous FTP user to be able to create 43 # new directories. 44 #anon_mkdir_write_enable=YES 45 # 46 # Activate directory messages - messages given to remote users when they 47 # go into a certain directory. 48 dirmessage_enable=YES 49 # 50 # If enabled, vsftpd will display directory listings with the time 51 # in your local time zone. The default is to display GMT. The 52 # times returned by the MDTM FTP command are also affected by this 53 # option. 54 use_localtime=YES 55 # 56 # Activate logging of uploads/downloads. 57 xferlog_enable=YES 58 # 59 # Make sure PORT transfer connections originate from port 20 (ftp-data). 60 connect_from_port_20=YES 61 # 62 # If you want, you can arrange for uploaded anonymous files to be owned by 63 # a different user. Note! Using "root" for uploaded files is not 64 # recommended! 65 #chown_uploads=YES 66 #chown_username=whoever 67 # 68 # You may override where the log file goes if you like. The default is shown 69 # below. 70 #xferlog_file=/var/log/vsftpd.log 71 # 72 # If you want, you can have your log file in standard ftpd xferlog format. 73 # Note that the default log file location is /var/log/xferlog in this case. 74 #xferlog_std_format=YES 75 # 76 # You may change the default value for timing out an idle session. 77 #idle_session_timeout=600 78 # 79 # You may change the default value for timing out a data connection. 80 #data_connection_timeout=120 81 # 82 # It is recommended that you define on your system a unique user which the 83 # ftp server can use as a totally isolated and unprivileged user. 84 #nopriv_user=ftpsecure 85 # 86 # Enable this and the server will recognise asynchronous ABOR requests. Not 87 # recommended for security (the code is non-trivial). Not enabling it, 88 # however, may confuse older FTP clients. 89 #async_abor_enable=YES 90 # 91 # By default the server will pretend to allow ASCII mode but in fact ignore 92 # the request. Turn on the below options to have the server actually do ASCII 93 # mangling on files when in ASCII mode. 94 # Beware that on some FTP servers, ASCII support allows a denial of service 95 # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd 96 # predicted this attack and has always been safe, reporting the size of the 97 # raw file. 98 # ASCII mangling is a horrible feature of the protocol. 99 #ascii_upload_enable=YES 100 #ascii_download_enable=YES 101 # 102 # You may fully customise the login banner string: 103 #ftpd_banner=Welcome to blah FTP service. 104 # 105 # You may specify a file of disallowed anonymous e-mail addresses. Apparently 106 # useful for combatting certain DoS attacks. 107 #deny_email_enable=YES 108 # (default follows) 109 #banned_email_file=/etc/vsftpd.banned_emails 110 # 111 # You may restrict local users to their home directories. See the FAQ for 112 # the possible risks in this before using chroot_local_user or 113 # chroot_list_enable below. 114 #chroot_local_user=YES 115 # 116 # You may specify an explicit list of local users to chroot() to their home 117 # directory. If chroot_local_user is YES, then this list becomes a list of 118 # users to NOT chroot(). 119 # (Warning! chroot'ing can be very dangerous. If using chroot, make sure that 120 # the user does not have write access to the top level directory within the 121 # chroot) 122 chroot_local_user=YES 123 chroot_list_enable=YES 124 # (default follows) 125 chroot_list_file=/etc/vsftpd.chroot_list 126 # 127 # You may activate the "-R" option to the builtin ls. This is disabled by 128 # default to avoid remote users being able to cause excessive I/O on large 129 # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume 130 # the presence of the "-R" option, so there is a strong case for enabling it. 131 #ls_recurse_enable=YES 132 # 133 # Customization 134 # 135 # Some of vsftpd's settings don't fit the filesystem layout by 136 # default. 137 # 138 # This option should be the name of a directory which is empty. Also, the 139 # directory should not be writable by the ftp user. This directory is used 140 # as a secure chroot() jail at times vsftpd does not require filesystem 141 # access. 142 secure_chroot_dir=/var/run/vsftpd/empty 143 # 144 # This string is the name of the PAM service vsftpd will use. 145 pam_service_name=vsftpd 146 # 147 # This option specifies the location of the RSA certificate to use for SSL 148 # encrypted connections. 149 rsa_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem 150 rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key 151 ssl_enable=NO 152 153 # 154 # Uncomment this to indicate that vsftpd use a utf8 filesystem. 155 #utf8_filesystem=YES 156 #Set default directory 157 local_root=/home/EFtp
注意：最后兩行原文中是沒有的，需要自己添加上去。
//再次提醒：把157行的EFtp改成你自己創建的FTP專用用戶名。
保存，退出文件。
運行命令：
sudo vim /etc/vsftpd.chroot_list
在新建的文件中輸入允許訪問FTP服務器的用戶名（一行一個）。這里我就寫的是：
EFtp
保存，退出文件。
打開最后一個需要更改的文件 (2020/7/30: 今天又試了一下，發現這一步不做也行。同志們可以先跳過這一步，如果有問題再補上)：
sudo vim /etc/pam.d/vsftpd
更改為如下（需要注意的行號已經標出。其他的地方有區別的話盡量不要管，只改我標出來的行）：
1 # Standard behaviour for ftpd(8). 2 auth required pam_listfile.so item=user sense=deny file=/etc/EFtp onerr=succeed 3 4 # Note: vsftpd handles anonymous logins on its own. Do not enable pam_ftp.so. 5 6 # Standard pam includes 7 @include common-account 8 @include common-session 9 @include common-auth 10 auth required pam_shells.so item=user sense=deny file=/etc/EFtp onerr=succeed
保存，退出。
最后，重啟一遍vsftpd服務
sudo service vsftpd restart
至此，FTP服務器已經配置成功，可以使用。
所有FTP服務器的文件會被存在/home/EFtp文件夾下
ps: 如果有什么錯誤發生，請在留言區提問，謝謝！