Updated dnsmasq packages that fix one security issue, one bug, and addvarious enhancements are now available for Red Hat Enterprise Linux 6.The Red Hat Security Response Team has rated this update as having moderatesecurity impact. A Common Vulnerability Scoring System base score,which gives a detailed severity rating, is available from the CVE link inthe References section. The dnsmasq packages contain Dnsmasq, a lightweight DNS forwarder and DHCP server.It was discovered that dnsmasq, when used in combination with certainlibvirtd configurations, could incorrectly process network packets fromnetwork interfaces that were intended to be prohibited. A remote,unauthenticated attacker could exploit this flaw to cause a denial ofservice via DNS amplification attacks. In order to fully address this issue, libvirt package users are advised toinstall updated libvirt packages. Refer to RHSA-2013:0276 for additionalinformation.This update also fixes the following bug:* Due to a regression, the lease change script was disabled. Consequently,the "dhcp-script" option in the /etc/dnsmasq.conf configuration file didnot work. This update corrects the problem and the "dhcp-script" option nowworks as expected. This update also adds the following enhancements:* Prior to this update, dnsmasq did not validate that the tftp directorygiven actually existed and was a directory. Consequently, configuration errors were not immediately reported on startup. This update improves thecode to validate the tftp root directory option. As a result, fault findingis simplified especially when dnsmasq is called by external processes suchas libvirt. * The dnsmasq init script used an incorrect Process Identifier in the"stop", "restart", and "condrestart" commands. Consequently, if there weresome dnsmasq instances running besides the system one started by the initscript, then repeated calling of "service dnsmasq" with "stop" or "restart"would kill all running dnsmasq instances, including ones not started withthe init script. The dnsmasq init script code has been corrected to obtainthe correct PID when calling the "stop", "restart", and "condrestart"commands. As a result, if there are dnsmasq instances running in additionto the system one started by the init script, then by calling "servicednsmasq" with "stop" or "restart" only the system one is stopped orrestarted. * When two or more dnsmasq processes were running with DHCP enabled on oneinterface, DHCP RELEASE packets were sometimes lost. Consequently, when twoor more dnsmasq processes were running with DHCP enabled on one interface,releasing IP addresses sometimes failed. This update sets theSO_BINDTODEVICE socket option on DHCP sockets if running dnsmasq with DHCPenabled on one interface. As a result, when two or more dnsmasq processesare running with DHCP enabled on one interface, they can release IPaddresses as expected. All users of dnsmasq are advised to upgrade to these updated packages,which fix these issues and add these enhancements.