How to Run C/C++ in Linux/Unix

Step1: Type the C/C++ source code using any text editor of your choice,
and save it with the extension .c for C programs and .cpp for C++ programs.

[linux c/cpp compiler, gcc, uses the extension of the source file to recognize the coding language].

Step2:To compile , assuming the source file name to be input_filename, type in the following command at the command prompt;

[root@localhost ~]# gcc -o

output_filename input_filename

Note:- there is no space between -o and output_filename

Step3: To run the output file, type in the following command at the command prompt:

[root@localhost ~]# ./

output_filename

END of Steps
--------------------------------

For example, to compile a source file named mysource.c, to produce an outputfile named myout, and to execute it, we can use the following steps:

[root@localhost ~]# gcc -o myout mysource.c
[root@localhost ~]# ./myout
.........................................................

How to ckeck the squid logs in real time:-

[root@localhost ~]#tail -f /var/log/squid/access.log

Note:-
tail - output the last part of file
-f - follow (output appented as the file grows)

How to Block Web sites using Squid..

Step1:-Open the /etc/squid/squid.conf file in any text editor ,preferably vim as shown below.

[root@localhost ~]#vim /etc/squid/squid.conf

Step2:-Search for the following set of lines to the script:

#Recommended minimum configuration:
………
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl internet src 192.168.1.0/255.255.255.0

Step3:-Now, add the following end of these lines to block the sites using acl (acl aclmame dstdomain "filename.squid")

acl badurl dstdomain “/etc/squid/bad-sites.squid”
........
........
Step4:-Search again for the following set of lines to the script:

#Only allow cachemgr access from localhost
http_access allow manager localhost
http_access deny manager

Step4:- Now, add the following end of these lines to deny the particular aclname using http_access (http_access deny aclname)

http_access deny badurl

:wq!

Step5:- Then create a new file /etc/squid/bad-sites.squid. Then enter the block web sites using following format.

[root@localhost ~]#vim /etc/squid/bad-sites.squid
…
.orkut.com
.youtube.com
:wq!

Step3:-Restart the squid service

[root@localhost ~]#service squid restart
[root@localhost ~]#chkconfig squid on

How to share internet using proxy Server

Step1: open the squid.conf file in any text editor ,preferably vim as shown below.

[root@localhost ~]#vim /etc/squid/squid.conf

Step2:Search for the following set of lines to the script:
.........
#Recommended minimum configuration:
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8

Step3: Now, add the following end of these lines to share the internet using acl,(acl aclname src xxx.xxx.xxx.xxx/yyy.yyy.yyy.yyy).

acl internet src 192.168.1.0/255.255.255.0
…
…
# And finally deny all other access to this proxy
http_access allow localhost
step4: Now, add the following end of these lines to allow the acl name (httpd_access allow aclname)

http_access allow internet
http_access deny all
...

Notes: -
internet -> acl name
src -> to specify source address
192.168.1.0/255.255.255.0 -> network address (or use ip address)

[root@localhost ~]#service squid restart //restart the service
[root@localhost ~]# chkconfig squid on // permanently ON the service

To configure firefox (Mozilla) using proxy server:-

Step1: open the firefox(Mozilla)
Step2:Edit->Preferences->General->Connection Settings

Step3: Ok.

Note:-
192.168.1.254 ->proxy server ip address
3128 -> default port no.

Step4: Restart the Service….

Squid Proxy Server on Linux (RHEL5)..

Purpose : Web caching, bandwidth management, URL surf control etc..

Proxy Server :squid

Package name : squid-2.6.STABLE6-3.el5

Service : squid

Configuration file : /etc/squid/squid.conf

Port no : 3128 / 8080 Tcp

Log files : /var/log/squid/access.log

Service Type : Standalone

Dependency : Network Service