Linux systems can be used as

– File Servers – Samba – Windows-compatible file server

– Print Servers –lpd, cups, etc.

– Mail Server – Sendmail (historically insecure), Qmail, Postfix

– VPN Server – FreeS/WAN

– Databases – PostgreSQL, MySQL (free), Oracle, Sybase, DB2 (commercial)

– DNS Servers – BIND

– LDAP Servers

– Time Servers