大部分IP分享器都是Linux kernel，IP分享器有支援Telnet/SSH登入，
直接修改/etc/hosts，把FTP對應IP加進去即可，Client端吃IP分享器DHCP
理論上什麼都不用改，內部固定IP就要確定DNS是設定IP分享器
以我的ASUS AC-68U為例:
代碼:
admin@RT-AC68U:/tmp/etc# ls
TZ hosts profile
cert.pem hotplug2.rules protocols
cfg_mnt key.pem rast_ipc_socket
cfgmnt_ipc_socket l7-protocols resolv.conf
dnsmasq.conf ld.so.conf server.pem
dropbear mtab services
email openssl.cnf shadow
ethertypes openvpn shadow.openvpn
fstab pam.d ssl
group passwd upnp
group.custom passwd.custom usb_modeswitch.conf
group.openvpn passwd.openvpn web
gshadow ppp wlcnt_socket
admin@RT-AC68U:/tmp/etc# vi /etc/hosts