1.27.2. RHBA-2011:1038: dhcp bug fix and enhancement update

Updated dhcp packages that fix several bugs and add an enhancement are now available for Red Hat Enterprise Linux 5.

The Dynamic Host Configuration Protocol (DHCP) is a protocol that allows individual devices on an IP network to get their own network configuration information, including an IP address, a subnet mask, and a broadcast address. DHCPv6 is the DHCP protocol version for IPv6 networks.

This update fixes the following bugs:

* Previously, the dhcpd service sometimes started to give new leases to clients in the INIT state rather than to presently active clients. That led to premature exhaustion of available leases for new clients. With this update, the server's "by client-id" and "by hardware address" hash table lists are sorted according to the preference to re-allocate the lease to returning clients, and the pool starvation problem no longer occurs in the described scenario. (BZ#615995)

* Previously, moving the server from the "communication-interrupted" state to the "partner-down" state did not force the server to take over the partner's leases. Consequently, clients could not get an IP address from the pool of the previously terminated DHCP server. With this update, a failover server in "partner-down" state is able to re-allocate leases to clients. (BZ#610219)

* Previously, the dhclient utility wasn't requesting the interface-mtu option by default. This caused difficulties when the network configuration changed and the MTU (Maximum Transmission Unit) value needed to be changed on all hosts. With this update, the dhclient utility requests the interface-mtu option by default. (BZ#694264)

* Previously, the dhcpd init script lacked several variables and actions required by the Linux Standard Base (LSB). With this update, the init script has been amended and it is now LSB-compliant. (BZ#610128)

* Previously, when the dhcpd service was used in a failover configuration, the primary server sometimes wrote so many "lease imbalance" messages into its log files, that it resulted in a termination. With this update, these messages are not logged unless rebalance is attempted, and the bug no longed occurs. (BZ#661939)

* Previously, when the system had been rebooted while the network switch had been down, after the network connection was recovered, the network interface configuration was not configured with DHCP, even if the dhclient utility was running in persistent mode. With this update, the dhclient-script file has been amended to refresh the ARP (Address Resolution Protocol) table and the routing table instead of bringing the interface down, which fixes the bug. (BZ#685048)

* Previously, when multiple DHCP clients were launched at the same time to handle multiple virtual interfaces on the same network interface card (NIC), the clients used the same seed to choose when to renew their leases. Consequently, virtual interfaces for some clients could have been deconfigured over time. With this update, the dhclient utility uses the PID (Process Identifier) for seeding the random number generator, which fixes the bug. (BZ#623953)

* Previously, it was impossible to configure the dhcrelay service to run the dhcrelay daemon with additional arguments. With this update, a DHCRELAYARGS variable is available for the /etc/sysconfig/dhcrelay configuration file, which allows additional arguments to be passed to the dhcrelay daemon properly. (BZ#624965)

* There was a small error regarding the dhcp-lease-time option in the dhclient.conf(5) man page. With this update, the man page has been amended. (BZ#585855)

This update adds the following enhancement:

* The dhcp package now provides support for IPoIB (IP over InfiniBand) interfaces. (BZ#660679)

Users of dhcp are advised to upgrade to these updated packages, which fix these bugs and add this enhancement.