Study Notes

Kevin,senior engineer from TaiWan,gave us a lecture about mail server producted by his company in Shanghai.

Internet mail,also called e-mail, are invented by some teachers in US, they uses email to exchange message with others as fast way.Twenty years passed, email became more and more important communication tool not only in college but also in business activities.In 2002,experts considered the security of mail was most important,so they work hard in encrypting package flowing in the network.but with the time goes into 2003,something changed,the mail users found a large number of letters contained information they did not want to read had been sent to their own mail-box.It was very annoy.The rubbish mail saved in the harddisk of mail-server causes waste and limit the transimition of network.So people dedicate their life to computer had to resolve this trouble.In 2004,many products about preventing rubbish mail were developed.

There are total three strategies, behavior,black-out,and content filter.

Behavior strategy collects the senders’ information and analyze their behavior, then help us to decide whether receive or refuse.This is the most popular mode.Black-out,which is also called Black name list,filters those mail from the address in the black name list.Such list would be created and update by Mail server administrator or by uses themselves.Content filter,reading the whole text of mail,and compares each word with those in the sepecial dictionary,once matched,the mail-server judged these mails as rubbish and refuse to receive.In fact,it is not a good ider for preventing rubbish mail because perhaps this strategy may refuse the mail which is not rubbish.We always find that the employees of the supermark distribute the colorful ad.paper,Do they break the law?The answer is denial.So does the email.But we must do something firmly to protect people’s privacy and prevent wasting resouces.

How do users access the specific website? The packages are sent to many routers.Routers is such device that direct next step or a good man tell you where to go next.It sent from router to router until find the specific website.Note, what is the difference bwteen http and https?Https means security http transmit by using SSL(security socket layout).In contrast,http does not have high security, because the sniffer installed in some routers may catch the information of packages.

For culture is very different all around world,one same mail,some people may think it is useful,but some people may refuse. So mechanism of mail server should also contain some mail which are judges by users themselves.The uses can read it or delete it without be effected too much.

Kevin said there were many rivals,we should let customer know our pruducts also contain rival’s advantage and surely instead them,or the sales told the Project Manager to improve our products in the next generation.However,we must not give the customer any information about new product in developing.That’s crazy.

Queue is the standard of judging mail server’s performance.A good mail server system has enough queue and send mails as soon as possible.It’s powerful.If the queus is not suitable,it will cause many troubles,for example,the mail is always waiting in the queue, it will never be sent.

SMTP server:snipper(for backup),relay(the most popular,about 90% in this market).

DNS constructure:
-Authority:resolute name step by step liking router(eg,abc.com.cn,cn –> com –> abc)
-Resolution:have a large database to record resolution items,the database is updated as finding new resolution recorder,so it becomes more and more bigger and intelligent.

In the SE7520BD2 platform,when I inserted USB disk any issue the following command:

# fdisk -l

I did not find usb device.So,”lsmod”, and reload the USB modules,”rmmod –> insmod”,and then
execute this command as root:

# cd /mnt
# mkdir a
# mount /dev/sda1 /mnt/a

Then,USB device was installed successfully.