中科大ubuntu 更新服务器（安徽省合肥市，推荐教育网,网通用户使用）：

deb http://debian.ustc.edu.cn/ubuntu/ jaunty main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ jaunty-security main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ jaunty-updates main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ jaunty-proposed main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ jaunty-backports main restricted universe multiverse
 完整阅读

1. 安装vnc4server

root@frank-desktop:~# sudo apt-get install vnc4server

2. 设置vnc密码

root@frank-desktop:~# vncpasswd
Password:
 完整阅读

As everyone knows, the NTP is sync clock protocol.
That knowledge less other protocol.
But there are some attention:
——————————————
1. When you config more than one server in customer network.
Please don’t use the same stratum.
Base on the stratum, refer to
http://www.cisco.com/en/US/docs/ios/netmgmt/command/reference/nm_10.html#wp1093957
If customer use same stratum, it would instability and lost sync.

2013-1-22 更新
There are two reason will lead NTP flapping(lost sync):
1. If you have 2 ntp servers this sort of behavour can happen if the ntp parameters from those servers are similar. This is likely if your peering to two N7Ks. Note also that “prefer” is not a priority selection on XR.
2. NTP version mismatch between V3 and V4

Refer to “Prefer” option, may solve this problem, in most of the case but this is not a 100% solution. If the time from the “preferred” source reaches the client earlier than other configured peers, it is taken to be authoritive and independent of the current time and offset. And we sync to it, but before the NTP client is synchronized to this preferred peer (which should take a few seconds in general or a maximum of 5 minutes), if time updates from other configured peers reach the NTP client, the clock selection algorithms are applied to all of these and we have all the time sources pass through the selection algorithms and NTP tunes the client’s time to some peer, considering the other factors of offset, sync distance and dispersion.

We do have more than 2 servers at the same stratum level, in the CASE, We should try using prefer option to see if we have no issues with time stabilities. But if we have the two servers almost at the same distance, even “prefer” option would not help much.

So it is advisable to to have one server per stratum level.

完整阅读

问题：

Customer have two 2500W power, now customer want to replace the 6000W power.
Customer want to check whether impact the business when replace the 6000W.

解决：

If customer have power usage exceeds need the downtime, as some of the linecards will go down due to lack of power. In case you have less than 2500w usage on the router, then follow the below steps.

1. have your power supply in redundant mode.
2. pull the power supply which is not active
完整阅读

一直想在Ubuntu下设置FTP服务器，但一直就没成功。
今天有些时间，经过测试终于成功了。
由于在linux中的ftp软件很多，这里我只介绍vsftpd。

1. 安装vsftpd

frank@frank-desktop:/etc/apt$ sudo apt-get install vsftpd

2. 配置

以下是我的配置，我只介绍我配置的主要参数，带“#”号的配置没有介绍，以后如果应用到其他配置，我会更新此文章。
完整阅读