本教程测试过程基于Newifi+PandoraBox/ 小云系统V3.0。理论上 OpenWrt原生同样适用。

修改路由器的软件源

dest root /
dest ram /tmp
lists_dir ext /var/opkg-lists
option overlay_root /overlay
src/gz 14.09_base http://downloads.openwrt.org.cn/PandoraBox/ralink/packages/base
src/gz 14.09_telephony http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/telephony
src/gz 14.09_packages http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/packages
src/gz 14.09_routing http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/routing
src/gz 14.09_management http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/management
arch ralink 1
arch all 2
arch ramips_24kec 3

注:软件源由于硬件配置不同的会有所区别，Newifi是MT7620方案，其他芯片方案的请移步以下两个网址自行匹配：

OpenWrt中文网址 http://downloads.openwrt.org.cn/
OpenWrt download area https://downloads.openwrt.org/

配置Odhcpd

• 软件包中更新并安装最新版本的odhcpd
• 修改dhcp文件（文件路径：/etc/config/dhcp，不熟悉ssh的可以使用winscp修改)

config dnsmasq
    option domainneeded '1'
    option boguspriv '1'
    option filterwin2k '0'
    option localise_queries '1'
    option rebind_protection '1'
    option rebind_localhost '1'
    option local '/lan/'
    option domain 'lan'
    option expandhosts '1'
    option nonegcache '0'
    option authoritative '1'
    option readethers '1'
    option leasefile '/tmp/dhcp.leases'
    option resolvfile '/tmp/resolv.conf.auto'
    option localservice '1'

config dhcp 'lan'
    option interface 'lan'
    option start '100'
    option limit '150'
    option leasetime '12h'
    option dhcpv6 'hybrid'
    option ra 'hybrid'
    option ndp 'hybrid'
    option ra_management '1'

config dhcp 'wan'
    option interface 'wan'
    option ignore '1'

config odhcpd 'odhcpd'
    option maindhcp '0'
    option leasefile '/tmp/hosts/odhcpd'
    option leasetrigger '/usr/sbin/odhcpd-update'

config dhcp 'wan6'
    option interface 'wan'
    option dhcpv6 'hybrid'
    option ra 'hybrid'
    option ndp 'hybrid'
    option master '1'

修改后保存并重启路由器即可。

后话

配置后好像dns出了一些问题，在访问其他校内以.byr.cn或.bupt.edu.cn为后缀的网址显示dns错误，如果有大牛解决了这个DNS问题，可以分享一下思路。
2018.9.9更新：后话所述问题已经解决
https://www.jianshu.com/p/644378ce25e3