配置BOOTP/DHCP选项
静态路由（DHCP选项33）--该配置已被淘汰，资料：https://tools.ietf.org/html/rfc3442，由rfc2132定义，被rfc3442淘汰
无类静态路由（DHCP选项121）
选项代码：121
类型：string
值：由16进制字符串组成，格式为 [子网掩码长度][IP地址的前三个数][路由地址]，结构如下
Code Len Destination 1 Router 1
+-----+---+----+-----+----+----+----+----+----+
| 121 | n | d1 | ... | dN | r1 | r2 | r3 | r4 |
+-----+---+----+-----+----+----+----+----+----+
Destination 2 Router 2
+----+-----+----+----+----+----+----+
| d1 | ... | dN | r1 | r2 | r3 | r4 |
+----+-----+----+----+----+----+----+
示例：IP范围：10.0.8.0/24，路由地址：192.168.1.1，转换完成如下 18:0a:00:08:c0:a8:01:01 由 24:10:0:8:192:168:1:1 这种格式转换而来。
资料来源：
https://www.reddit.com/r/PFSENSE/comments/5ei112/dhcpoptions_pushing_a_static_route/
https://forum.netgate.com/topic/67684/explained-example-dhcp-option-121-249/2
https://ercpe.de/blog/advanced-dhcp-options-pushing-static-routes-to-clients
https://www.freebsd.org/cgi/man.cgi?query=dhcp-options&sektion=5
https://forum.netgate.com/topic/25087/dhcp-option-121-249-please-help-provide-static-routes-via-dhcp-to-win-clients/15
https://tools.ietf.org/html/rfc3442
https://tools.ietf.org/html/rfc2132
http://www.networksorcery.com/enp/protocol/bootp/options.htm
http://www.networksorcery.com/enp/protocol/bootp/option033.htm
