搭建这个ftp服务器是用来给cisco路由器升级用，难度较低，几步就可以搞定。
1、安装vsftpd软件包, 先来个apt三连
sudo apt update
sudo apt upgrade
sudo apt install vsftpd
2、装完了修改配置文件vim /etc/vsftpd.conf，如果不考虑允许匿名用户的话，改两条就好了
# Run standalone? vsftpd can run either from an inetd or as a standalone
# daemon started from an initscript.
listen=YES
#
# This directive enables listening on IPv6 sockets. By default, listening
# on the IPv6 "any" address (::) will accept connections from both IPv6
# and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6
# sockets. If you want that (perhaps because you want to listen on specific
# addresses) then you must run two copies of vsftpd with two configuration
# files.
listen_ipv6=NO
#
3、配置ftp用户和组，这里用户名叫cfl-ftpuser， 随便叫啥不重要，加完了设下权限
sudo groupadd ftpuser
sudo mkdir /home/cfl-ftpuser
sudo useradd -g ftpuser cfl-ftpuser
sudo passwd cfl-ftpuser # 输入两次密码
#改下密码文件 /etc/passwd, 把/bin/sh改成/bin/bash
sudo vim /etc/passwd
cfl-ftpuser:x:1005:1003::/home/cfl-ftpuser:/bin/bash
#把家目录权限设好
sudo chown -v -R cfl-ftpuser:ftpuser /home/cfl-ftpuser/
sudo chmod -v -R 700 /home/cfl-ftpuser/
4、重启vsftpd
sudo systemctl restart vsftpd
或者
sudo service vsftpd restart
5、记得开启防火墙ftp端口
sudo ufw allow ftp
6、测试一下，可以在本机上ftp 127.0.0.1， 也可以远程ftp到服务器上put或者get一个文件看看。在Cisco路由器上，copy ftp的语法是这样的：
ftp:[[[//username [:password]@] location]/directory]/filename
