DHCP Server某網段的IP range被用完了該怎麼辦？

做實驗時不小心把某個網段的IP scope用完了，距離release時間有一天，影響到新的client拿不到IP了，靈機一動就想把它手動砍掉吧！不過我要對付的是整個IP scope，嘿嘿～派出sed一行指令就結束了。

Steps:

1. dhcpd的lease table是放在/var/lib/dhcpd/dhcpd.leases

2. 檢查一下格式:

lease 10.10.6.125 {
  starts 2 2012/10/16 22:12:53;
  ends 3 2012/10/17 22:12:53;
  tstp 3 2012/10/17 22:12:53;
  binding state active;
  next binding state free;
  hardware ethernet b8:ac:6f:21:53:ec;
  uid "\001\270\254o!S\354";
  client-hostname "D129252S";
}

10.10.6這個range被fake DHCP client用完了，所以我要把它們手動通通砍掉。

3. Sed:

sed -i "/10.10.6/,/}/d" /var/lib/dhcpd/dhcpd.leases

4. 重啟DHCP Server:

# /etc/init.d/dhcpd restart

參考: http://en.kioskea.net/faq/1451-sed-delete-one-or-more-lines-from-a-file

Install Monitorix on CentOS

Monitorix是一套free, open的套件能幫助系統管理者觀察主機的各種狀況，比如網路的流量，磁碟的使用率與服務的負載等等。安裝與配置的方法則是出乎意料的簡單。

Step1. Installation:

# yum install httpd rrdtool rrdtool-perl perl-libwww-perl perl-MailTools perl-MIME-Lite perl-CGI perl-DBI perl-XML-Simple

# rpm -ivh http://www.monitorix.org/monitorix-n.n.n-1.noarch.rpm
(where n.n.n is the latest version,2.6.0 for example)

Step2. Configuration:

Configure file is in /etc/monitorix.conf
Apache configure file is in /etc/httpd/conf.d/monitorix.conf, and you need to configure it allow connect to Monitorix from any where.

Step3. Restart service:

# /etc/init.d/monitorix start && chkconfig monitorix on
# /etc/init.d/httpd restart && chkconfig httpd on

Step4. Access:
http://X.X.X.X/monitorix/
(Where X.X.X.X is your IP address)