security in samba

[Yunjung Hyun]

Hi,

I am wonderng whether or not samba has some function related with
security.

In our group, we used to use 'samba' in UNIX machine (OS: AIX 4.3). One
day the UNIX machines were broken by a hacker, and we could not figure 
out how the hacker could break the system. So now we are concerned to 
keep using 'samba' for this security matter. 
Is there any function that samba can help for security?
I had 'hosts allow' commands in configuration file. 
I am also wondering if 'hosts allow' function is reliable enough for
security.

Look forward to help.