Here I have listed out the Open Source products which are replacing the commercial products
1) Mail Server
Linux Sendmail with cyrus-imap is the good opensource replace for other commercial mailing solutions like Microsoft Exchange , Lotus Notes etc. We can integrate MailScanner and Clam-AV with Sendmail.
2) Web Server
Apache web server can be used as a Replace for Microsoft IIS
3) Active Directory
Fedora DS Replace Microsoft AD
4) Proxy Server
Squid Proxy server is one of the best proxy server. Squid can be configured with lots of Access controls. Content filter, Upload & Download Limit, User Base access, time based access, block list, are the key features.
5) UTM
Untangle , pfsense
6) Database
Mysql,
7) FTP Server
vsftpd
8) Network Monitoring Tools
Cacti, zabbix,
9) Asset Management
GLPI
10) Bug Tracking
Bugzilla
11) Web Mail
Ilohamail, roundcube
12) Other Open source Web based Applications
