Hello,

I have RedHat 4 ES box with all services are installed (web,ftp,mail).can anybody tell me how to block certain hosts or IP addresses to access services on my box. Example, I need to block these hosts(192.168.0.1 and 192.168.0.2)to access any services(mainly sshd) on my box and others can have access. Is this possible via IP tables or TCP wrappers? Please explain with examples...

Thanks

Yes you can do all of that with either a firewall or TCP wrappers. For examples on TCP wrappers check out

http://docsrv.sco.com/NET_tcpip/filt...p_wrap_ex.html
http://linux.about.com/od/commands/l...stsde.htm?rd=1
(both easily found with google)

For setting up a linux firewall I recommend using a program such as firestarter. Once the firewall is setup you don't actually have to use the program anymore. Firestarter also has this nice feature that allows you to see hits on your firewall as they happen and allows you to easily modify your fireall based upon the information you gather from the event. If you would rather do it the manual way then I suggest checking out a page such as http://tldp.org/HOWTO/Firewall-HOWTO.html.

I personally just use TCP wrappers to deny everything unless explicitly allowed (ALL:ALL in hosts.deny) and then use a firewall to do the rest.

Thank you for your information!! That firestarter firewall certainly good

To find out wether you could use tcp_wrapper with your application try this one:

If the program is linked with libwrap.so (==1) then tcp_wrapper will work. Else it won't (==0)