I did follow:
1. Installling libaio1 (must for Oracle 11g, optional for 10):
apt-get install libaio1
2. Installing alien:
apt-get install alien
3. Downloading RPMs from here:
http://www.oracle.com/technetwork/topics/linuxsoft-082809.html
4. RPMs converting into .deb through alien:
alien [download_file.rpm]
5. Installing debian-package:
dpkg -i [file_from_paragraph_4.deb]
aptitude search oracle
And we must see:
p cl-sql-oracle - CLSQL database backend, Oracle p libmono-oracle1.0-cil - Mono Oracle library p libmono-oracle2.0-cil - Mono Oracle library i oracle-instantclient11.1-basic - Instant Client for Oracle Database 11g i oracle-instantclient11.1-devel - Development headers for Instant Client. i oracle-instantclient11.1-sqlplus - SQL*Plus for Instant Client. p spamoracle - A statistical analysis spam filter based on Bayes' formula p spamoracle-byte - A statistical analysis spam filter based on Bayes' formula