Server hacked on known port Post: 303029984

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Special Forums Cybersecurity Server hacked on known port Post 303029984 by bakunin on Monday 4th of February 2019 06:37:06 AM

02-04-2019

Registered User

If i remember correctly 1521 is one of the standard ports for the Oracle listener, so i suppose you have an Oracle database running there. That the listener listens is quite as it should be, no?

What makes you think the server "was hacked"?

I mean, iptables is just a packet filter and as such it cannot discern between legitimate content and an illegitimate one. It filters packets based on IP address (layer 3) and port (layer 4), nothing more, nothing less. Obviously you need to allow traffic to the configured port of the listener otherwise the database would not be usable. So either you allow this port or you disable it (eventually restricting to a certain range of IP addresses), but what content goes over this port (i.e. legitimate database queries vs. malicious content) the packet filter is the wrong tool to assess. For that you will need a "stateful inspection" type of firewall which iptables is not.

Also be aware that the concept of "host based firewalls" is a flawed one per design. A hosts role is either providing a service (that is: some application) OR providing firewall services, but not both! The reason is you don't want the host you want to protect run the firewall itself, beause in this scenario the malicious packages already have reached the interface they are trying to attack. You want the firewall in front of (and separated from) the host you try to protect so that the malicious content doesn't even reach the interface you want to protect.

I hope this helps.

bakunin

Last edited by bakunin; 02-04-2019 at 05:08 PM.. Reason: confused "stateful inspection" with "deep state inspection" - oh, the paranoia

bakunin

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ipkungfu

ipkungfu(8)						      System Manager's Manual						       ipkungfu(8)

NAME

       ipkungfu - An iptables-based firewall for Linux

SYNOPSIS

       ipkungfu [ -c ] [ -t ] [ -d ] [ -h ] [ -v ] [ --quiet ] [ --panic ] [ --no-caching

DESCRIPTION

       ipkungfu  is an iptables-based Linux firewall. The primary design goals are security, ease of use, and performance, in that order. It takes
       advantage of advanced features of iptables, tcpwrappers, and the Linux kernel. It also simplifies the configuration of internet	connection
       sharing, advanced routing, and other networking needs.

OPTIONS

       -c  (or	--check)
		   Check whether ipkungfu is loaded, and report any command line options it may have been loaded with.

       -t  (or	--test)
		   Runs  a configuration test, and displays the results.  Note that this does not test or display all configuration options.  This
		   gives you an opportunity to verify that major configuration options are correct before putting them into action.

       -d  (or	--disable)
		   Disables the firewall.  It is important to know exactly what this option does.  All traffic is allowed in and out, and  in  the
		   case  of  a gateway, all NATed traffic is forwarded (the option retains your connection sharing options).  Custom rules are not
		   implemented, and deny_hosts.conf is ignored.

       -f  (or	--flush)
		   Disables the firewall COMPLETELY.  All rules are flushed, all chains are removed.  Any port forwarding or  internet	connection
		   sharing will cease to work.

       -h  (or	--help)
		   Displays brief usage information and exits.

       -v  (or	--version)
		   Displays version information and exits.

       --quiet	   Runs ipkungfu with no standard output

       --panic	   Drops  ALL traffic in all directions on all network interfaces.  You should probably never use this option.	The --panic option
		   is available for the highly unusual situation where you know that an attack is underway but you know of no other  way  to  stop
		   it.

       --failsafe  If  ipkungfu fails, --failsafe will cause all firewall policies to revert to ACCEPT.  This is useful when working with ipkungfu
		   remotely, to prevent loss of remote access due to firewall failure.

       --no-caching
		   Disables rules caching feature.

FILES

       /etc/ipkungfu/ipkungfu.conf
       /etc/ipkungfu/advanced.conf
       /etc/ipkungfu/accept_hosts.conf
       /etc/ipkungfu/deny_hosts.conf
       /etc/ipkungfu/custom.conf
       /etc/ipkungfu/log.conf
       /etc/ipkungfu/redirect.conf
       /etc/ipkungfu/services.conf
       /usr/sbin/ipkungfu
       /usr/share/doc/ipkungfu/AUTHORS
       /usr/share/doc/ipkungfu/README
       /usr/share/doc/ipkungfu/FAQ
       /usr/share/doc/ipkungfu/ChangeLog
       /usr/share/doc/ipkungfu/COPYING

SEE ALSO

       iptables(8).

								   January 2003 						       ipkungfu(8)