https://linuxhint.com/install_tftp_server_centos7/
搞了一整天，結果是OS bug...
簡單的來說 換了RHEL8之後tftp一直不能傳，看fw會有異常的unreachable - admin prohibited filter
disable firewalld就會好，但總不能一直這樣吧....
3.106310 wan1 -- 192.168.26.26.23814 -> 192.168..100.33.69: udp 26
3.114525 wan1 -- 192.168..100.33.43341 -> 192.168.26.26.23814: udp 4
3.114943 wan1 -- 192.168.26.26 -> 192.168..100.33: icmp: host 192.168.26.26 unreachable - admin prohibited filter
8.105289 wan1 -- 192.168.26.26.23814 -> 192.168..100.33.69: udp 26
8.113544 wan1 -- 192.168..100.33.43342 -> 192.168.26.26.23814: udp 4
8.113931 wan1 -- 192.168.26.26 -> 192.168..100.33: icmp: host 192.168.26.26 unreachable - admin prohibited filter
怎麼改規則，怎麼加port都沒有效的...
/bin/firewall-cmd --permanent --zone public --add-service tftp-client
firewall-cmd --reload
sudo firewall-cmd --permanent --add-port=69/udp
sudo firewall-cmd --zone=public --add-service=tftp --permanent
firewall-cmd --reload