logs
 

where can I find the logs from the ssh conection ? or the logs from ftp and sendmail conections ? If the loging system is not started how can I start it ?

By default, ssh logs will be mixed in with /var/log/messages from what I've experienced.

Usually on most systems system logs are started with the syslogd daemon.

SSH logs generally, goes into: /var/log/secure, /var/log/messages
Sendmail: /var/log/maillog
FTP: /var/log/xferlog (depends in FTP server)

/etc/init.d/syslogd restart
will log into /var/log/messages

hope this helps,

how can I figure out that a hosts scans me ?

The answer to your original question:
su -
enter root password
cat /var/logs/messages|grep ssh|more (to view all ssh logs)
cat /var/logs/messages|grep ftp|more (to view all ftp logs)
etc, etc, etc

The answer to the scanning question:
Install portsenty.