Sheikji Nazirudeen wrote:
> Hello:
>   I am in the process of scanning HP and Sun servers. I am running into
> issues wherein, it takes a long time for the scan to complete. Is there any
> way apart from exculding certain file extensions to increase the speed. I
> would be much interested in a software solution. Let me know.

This is an opportunity to ask the providers a related question: Does ClamAV use 
every 
pattern file record and all heuristics on every file it scans? It makes little 
sense 
to use Phishing/Image spam/Scam/Windows-only patterns, and certain heuristics 
operations on Sparc ELF binaries in /usr/sbin on Sun servers, for example.

And to answer in part your question, one performance hit is scanning NFS 
mounted 
directories and there's usually ways to avoid that. And if you have very large 
directories as was the case where I worked, limiting the scan to only those 
files 
that have changed since the last scan helps. Arrange your scanning so that 
there are 
few startup costs. Each time clamscan starts up it has to load all the 
databases from 
scratch so get the most from this expense. Clamd running as an unprivileged 
user 
cannot be used to scan a lot of file areas. Consider a limited life instance of 
running clamd with greater privileges and with a config file that forces this 
clamd 
instance to operate only in protected space regards its own socket files, temp 
files, 
working area, and database files. Prune if possible unlikely candidates from 
the 
database files. If you have any form of a "SoBig" virus in your Sun server 
binaries 
you should already know about it without having to run clamav's tools.

If you have a good tripwire like tool then you can eliminate a lot of files 
from 
scanning requirements and improve your intrusion detection capacity. Even if I 
didn't 
have ClamAV I'd still run TripWire or aset for this added security. Various 
archive 
files such as .z, .bz2, .gz, .tgz, for example, that have not changed in a way 
that 
TripWire like tools can detect are probably good candidates to ignore for 
future 
scanning, assuming they have been scanned and found clean at the time they were 
TripWired.

ClamAV is optimized as a mail scanner for incoming mail. It is less useful for 
mail 
that has been delivered to an mbox file, and is very Windows-centric in terms 
of 
viruses it's looking for. In the final analysis it may not be the best tool for 
scanning Unix file systems, or may require other processes to augment it's 
effort.

dp
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