diff -up dhcp-4.2.2/client/dhclient.c.improved-xid dhcp-4.2.2/client/dhclient.c

--- dhcp-4.2.2/client/dhclient.c.improved-xid	2011-09-16 18:18:00.649730661 +0200

+++ dhcp-4.2.2/client/dhclient.c	2011-09-16 18:22:36.815035513 +0200

@@ -898,6 +898,26 @@ main(int argc, char **argv) {

 		}

 	}

+	/* We create a backup seed before rediscovering interfaces in order to

+	   have a seed built using all of the available interfaces

+	   It's interesting if required interfaces doesn't let us defined

+	   a really unique seed due to a lack of valid HW addr later

+	   (this is the case with DHCP over IB)

+	   We only use the last device as using a sum could broke the

+	   uniqueness of the seed among multiple nodes

+	 */

+	unsigned backup_seed = 0;

+	for (ip = interfaces; ip; ip = ip -> next) {

+		int junk;

+		if ( ip -> hw_address.hlen <= sizeof seed )

+		  continue;

+		memcpy (&junk,

+			&ip -> hw_address.hbuf [ip -> hw_address.hlen -

+						sizeof seed], sizeof seed);

+		backup_seed = junk;

+	}

+

+

 	/* At this point, all the interfaces that the script thinks

 	   are relevant should be running, so now we once again call

 	   discover_interfaces(), and this time ask it to actually set

@@ -912,14 +932,36 @@ main(int argc, char **argv) {

 	   Not much entropy, but we're booting, so we're not likely to

 	   find anything better. */

 	seed = 0;

+	int seed_flag = 0;

 	for (ip = interfaces; ip; ip = ip->next) {

 		int junk;

+		if ( ip -> hw_address.hlen <= sizeof seed )

+		  continue;

 		memcpy(&junk,

 		       &ip->hw_address.hbuf[ip->hw_address.hlen -

 					    sizeof seed], sizeof seed);

 		seed += junk;

+		seed_flag = 1;

 	}

-	srandom(seed + cur_time + (unsigned)getpid());

+	if ( seed_flag == 0 ) {

+		if ( backup_seed != 0 ) {

+		  seed = backup_seed;

+		  log_info ("xid: rand init seed (0x%x) built using all"

+			    " available interfaces",seed);

+		}

+		else {

+		  seed = cur_time^((unsigned) gethostid()) ;

+		  log_info ("xid: warning: no netdev with useable HWADDR found"

+			    " for seed's uniqueness enforcement");

+		  log_info ("xid: rand init seed (0x%x) built using gethostid",

+			    seed);

+		}

+		/* we only use seed and no current time as a broadcast reply */

+		/* will certainly be used by the hwaddrless interface */

+		srandom(seed);

+	}

+	else

+	        srandom(seed + cur_time + (unsigned)getpid());

 	/* Setup specific Infiniband options */

 	for (ip = interfaces; ip; ip = ip->next) {

@@ -1457,7 +1499,7 @@ void dhcpack (packet)

 		return;

 	}

-	log_info ("DHCPACK from %s", piaddr (packet -> client_addr));

+	log_info ("DHCPACK from %s (xid=0x%x)", piaddr (packet -> client_addr), client -> xid);

 	lease = packet_to_lease (packet, client);

 	if (!lease) {

@@ -2174,7 +2216,7 @@ void dhcpnak (packet)

 		return;

 	}

-	log_info ("DHCPNAK from %s", piaddr (packet -> client_addr));

+	log_info ("DHCPNAK from %s (xid=0x%x)", piaddr (packet -> client_addr), client -> xid);

 	if (!client -> active) {

 #if defined (DEBUG)

@@ -2300,10 +2342,10 @@ void send_discover (cpp)

 		client -> packet.secs = htons (65535);

 	client -> secs = client -> packet.secs;

-	log_info ("DHCPDISCOVER on %s to %s port %d interval %ld",

+	log_info ("DHCPDISCOVER on %s to %s port %d interval %ld (xid=0x%x)",

 	      client -> name ? client -> name : client -> interface -> name,

 	      inet_ntoa (sockaddr_broadcast.sin_addr),

-	      ntohs (sockaddr_broadcast.sin_port), (long)(client -> interval));

+	      ntohs (sockaddr_broadcast.sin_port), (long)(client -> interval), client -> xid);

 	/* Send out a packet. */

 	result = send_packet (client -> interface, (struct packet *)0,

@@ -2584,10 +2626,10 @@ void send_request (cpp)

 			client -> packet.secs = htons (65535);

 	}

-	log_info ("DHCPREQUEST on %s to %s port %d",

+	log_info ("DHCPREQUEST on %s to %s port %d (xid=0x%x)",

 	      client -> name ? client -> name : client -> interface -> name,

 	      inet_ntoa (destination.sin_addr),

-	      ntohs (destination.sin_port));

+	      ntohs (destination.sin_port), client -> xid);

 	if (destination.sin_addr.s_addr != INADDR_BROADCAST &&

 	    fallback_interface)

@@ -2618,10 +2660,10 @@ void send_decline (cpp)

 	int result;

-	log_info ("DHCPDECLINE on %s to %s port %d",

+	log_info ("DHCPDECLINE on %s to %s port %d (xid=0x%x)",

 	      client -> name ? client -> name : client -> interface -> name,

 	      inet_ntoa (sockaddr_broadcast.sin_addr),

-	      ntohs (sockaddr_broadcast.sin_port));

+	      ntohs (sockaddr_broadcast.sin_port), client -> xid);

 	/* Send out a packet. */

 	result = send_packet (client -> interface, (struct packet *)0,

@@ -2661,10 +2703,10 @@ void send_release (cpp)

 		return;

 	}

-	log_info ("DHCPRELEASE on %s to %s port %d",

+	log_info ("DHCPRELEASE on %s to %s port %d (xid=0x%x)",

 	      client -> name ? client -> name : client -> interface -> name,

 	      inet_ntoa (destination.sin_addr),

-	      ntohs (destination.sin_port));

+	      ntohs (destination.sin_port), client -> xid);

 	if (fallback_interface)

 		result = send_packet (fallback_interface,