How do I find the software in linux ?

use the terminal, type:

retnet @ retnet: ~ $ apt-cache search security camera
camstream - collection of tools for webcams and other video-devices
zoneminder - Linux video camera security and surveillance solution

or

retnet@retnet:~$ apt-cache search webcam
motion - V4L capture program supporting motion detection
cheese - A tool to take pictures and videos from your webcam
aatv - A program to watch TV in a text-based console
came - Rewrite of the xawtv webcam app using imlib2
cameramonitor - Webcam monitoring in system tray
camgrab - A command line tool to download a single image from a webcam
camorama - gnome utility to view and save images from a webcam
camstream - collection of tools for webcams and other video-devices
camstream-doc - documentation for CamStream

emesene - platform independent MSN Messenger client
feh - imlib2 based image viewer

fswebcam - Tiny and flexible webcam program
geekast - GNOME interface to peercast
geekast-binary - GNOME interface to peercast - binaries
gkrellkam - GKrellM plugin that displays a periodically updating image
gmotionlive - A simple multipart/x-mixed-replace viewer
kamoso - Tool to take pictures and videos from your webcam
libdecodeqr-dev - A C/C++ library for decoding QR code
libdecodeqr-examples - Sample program in C/C++ library for decoding QR code
libdecodeqr0 - A C/C++ library for decoding QR code
.............

or

retnet @ retnet: ~ $ apt-cache search virus
clamav - anti-virus utility for Unix - command-line interface
clamav-base - anti-virus utility for Unix - base package
clamav-daemon - anti-virus utility for Unix - scanner daemon
clamav-dbg - debug symbols for ClamAV
clamav-docs - anti-virus utility for Unix - documentation
clamav-freshclam - anti-virus utility for Unix - virus database update utility
libclamav-dev - anti-virus utility for Unix - development files
libclamav6 - anti-virus utility for Unix - library
clamav-milter - anti-virus utility for Unix - sendmail integration
clamav-testfiles - anti-virus utility for Unix - test files
amavisd-new - Interface between MTA and virus scanner/content filters
exim4-daemon-heavy - Exim MTA (v4) daemon with extended features, including exiscan-acl
amavis-stats - Virus statistics RRDtool frontend for Amavis
amavisd-new-milter - Interface between sendmail-milter and amavisd-new
clamassassin - email virus filter wrapper for ClamAV
clamav-getfiles - Update script for clamav
clamfs - user-space anti-virus protected file system
clamsmtp - virus-scanning SMTP proxy
dansguardian - Web content filtering
frox - Transparent caching ftp proxy
graphdefang - grapher for MIMEDefang spam and virus logs
havp - HTTP Anti Virus Proxy
klamav - KDE frontend for ClamAV
libclamav-client-perl - A client for the ClamAV virus scanner daemon
libfile-scan-perl - Perl lib to scan files for viruses
libspf2-2 - library for validating mail senders with SPF
libspf2-dev - Header and development libraries for libspf2
linkchecker - check websites and HTML documents for broken links
mailscanner - email gateway for virus scanning, spam and phishing detection
nautilus-clamscan - Antivirus scanning for Nautilus
nomarch - Unpacks .ARC and .ARK MS-DOS archives
p3scan - transparent POP3-proxy with virus- and spam-scanning
partimage - backup partitions into a compressed image file
picalib - Set of PICA helper scripts and configuration files
policyd-weight - a Perl policy daemon for the Postfix MTA
proxsmtp - multi purpose SMTP Proxy
python-clamav - Python bindings to ClamAV
python-pyclamd - Python interface to the ClamAV daemon

then select the one you want to install.

example:

retnet @ retnet: ~ $ sudo apt-get install cheese

then wait until the end.
after that search in applications - sound and video - cheese

good luck.