远程登录到服务器，执行dir/ls等命令，一律是：
ftp> ls 500 Illegal PORT command. ftp> dir 500 Illegal PORT command.
服务器有问题？上网搜索，很多人都人云亦云，自己都没试用。找了半天，终于找到了一个解决办法。即使用quote/passive更改模式：
ftp> quote pasv 227 Entering Passive Mode (192,168,2,2,1111,5555) ftp> passive Passive mode on. ftp> dir 227 Entering Passive Mode (192,168,2,3,117,56) 150 Here comes the directory listing. drwxr-xr-x 9 0 0 220 Sep 16 2019 apache-tomcat-8.5.46 drwxr-x--- 3 0 0 18 Nov 20 2020 apache-tomcat-home drwxr-xr-x 9 0 0 202 Aug 19 2020 apache-tomcat-plugin_test drwxr-xr-x 9 0 0 220 Jul 03 2020 apache-tomcat-reader drwxrwxr-x 9 1123 1123 220 Aug 12 2020 apache-tomcat-temp-test drwxr-xr-x 9 0 0 220 Jul 03 2020 apache-tomcat-upgrade drwxr-x--- 3 0 0 18 Nov 20 2020 apache-tomcat-wo 226 Directory send OK.
