The Diary of a SysAdmin

In name based virtual hosting we run several web sites in one IP address.To do that request from browser should come in HTTP/1.1 protocol. To demonstrate this process I used this scenario. Imagine we have three web sites called as www.bict,lk , www.ucsc.lk and www.scs.lk. And our apache server runs in 192.168.1.1IP address and 8080 port. Following document roots are used. www.bict.lk    /var/opt/www.bict.lk/htdocs www.ucsc.lk   /var/opt/www.ucsc.lk/htdocs www.scs.lk   /var/opt/www.scs.lk/htdocs In an each htdocs directory you should create separate index.html files. note : You can change those document root in /etc/apache/sites-available/default file. And it has default document root as /var/www . To edit that use $ vi /etc/apache/sites-available/default    command. There should be a index files (index.html) relevant to each web site. To make easy understand I explain this step by step . step 1.      Edit the ports.conf file     $vi /etc/apache2/ports.conf     In thi

In this article I try to explain how to create our own log file in apache2. Log files are there to keep records about the details of users ,time , host's IP  etc.. These details are used to analyzed about the users who visits web sites. First of all you had to create a web site and should host in apache server.Following guidelines will help to you.According to your document root create a directories to keep your index file. In my case I keep it /var/www/www.mypage.lk/htdocs. If you are not define custom log file to your site it will go to default place in /var/log/apache2 .And I create a log directory in side the www.mypage.lk to keep records of www.mypage.lk. Normally log files are keep in /var/log/apache2. This is the default directory where apache log files are keep.  In this scenario I create log directory inside the www.mypage.lk directory. So my log file path will be /var/www/www.mypage.lk/logs. go to /etc/apache2 and edit ports.conf file ( you can use an editor like v

I think most of the people used ubuntu as their linux OS. There will be a little bit conflict when you are trying to use virtual hosting in apache2 according to centOS. In this article I will try to explain how it should done in ubuntu apache2. Anyway there is a few more things to know before you start. 1. httpd.conf  file is equal to apache2.conf in /etc/apache2/ 2. In apache2.conf includes some other conf file so that necessary settings should be done those files. e.g. changing port numbers should be done in ports.conf I will explain step by step vertual hosting using apacge2. I take /etc/var/www as a DocumentRoot any way if you want to change it, Change the default file which locate in /etc/apache2/sites-available/default file. To easy access create a folder called www.bict.lk (any choice)  and create htdocs and logs two folders inside www.bict.lk. Don't forget to create index.html file in htdocs folder. (html file which shows www.bict.lk ). These folders should be cre

I think it is better to tell the difference of Subnet Mask and Variable Length Subnet Mask(VLSM) at the beginning. As I discuss in earlier article Subnet Mask is there to split one IP address into several IP’s which can use in difference LAN’s. But the question is it limit the number of accessible hosts(computers) in each LAN.  Let takes the previous example,  192.168.5.0/26 (LAN A) can only have 62 (2^6 -2) computers(hosts). But Imagine that we need to keep 100 computers in LAB A? Now I think you can understand how Subnet Mask is questioned. The answer is Variable Length Subnet Mask. I try to discuss how we use VLSM in practice in this article. I rearrange the previous example as following. ISP given address -> 192.168.5.0 /24 LAN A -> 100  (lets think LAN A need 100 computers). LAN B ->50 LAN C -> 50 LAN D ->50 Let see how we solve this problem. 192.168.5.0 /24 is the given IP and we take one bit from host side of that IP. We can define two different IP’s b

Imagine that you need to make four different networks(LAN’s). Then you ask form ISP(Internet Service Provider) to four different IP’s. But each of network has less than 20 computers. So ISP will say we cannot give four IP’s and we give you one IP and Split it into four difference networks. Let see how we done it. ISP given network address: 192.168.5.0 255.255.255.0                                                                                                                                  The number of networks that we have : 4 (2^2) 192.168.5. 00 000000        (we take two bits from available host’s bits because we need four different networks).       0     0     0   0   0  0  0   0        (consider last 8 bits) 128  64  32 16  8  4  2   1 00  -> 192.168.5.0       LAN A                                01 -> 192.168.5.64      LAN B 10 ->192.168.5.128     LAN C 11 ->192.168.5.192      LAN D LAN Name Network Address Broadcast Address Host’s IP Range

As I mention in earlier article network address will give when we make all host side bits zero. The main difference between class full and class less IP addressing is there is no standard bit position to divide network and host side in class less IP. But we had to tell what is the point that network and host side divide in this case. That is why sub net mask address comes to seen. Subnet mask address is also 32 bit binary number. The sub net mask address will give when all network side bits makes 1(one ‘s) and all host side bits makes 0(zero). I think you can take better idea by looking  following e.g. e.g. 1 IP Addr: 192.168.1.1                                        11000000.10101000.00000001 .00000001 Sub net mask: 255.255.255.0                             11111111.11111111.11111111 .00000000 We can write both IP and sub net mask or can write like this, 192.168.1.1/24. Number of network side bits are written as “/n “ after the IP.    e.g.2 Let say 192.168.1.1/26 and a