o Document net.inet.ip.portrange.random* sysctls.

o Correct a comment about random port allocation threshold
implementation.

Reviewed by:	silby, ru
MFC after:	3 days

2 files changed, 26 insertions, 8 deletions

diff --git a/share/man/man4/ip.4 b/share/man/man4/ip.4
index dd86514..65dd308 100644
--- a/share/man/man4/ip.4
+++ b/share/man/man4/ip.4
@@ -32,7 +32,7 @@
 .\"     @(#)ip.4	8.2 (Berkeley) 11/30/93
 .\" $FreeBSD$
 .\"
-.Dd June 14, 2004
+.Dd March 23, 2005
 .Dt IP 4
 .Os
 .Sh NAME
@@ -331,6 +331,21 @@ In scenarios such as benchmarking, this behavior may be undesirable.
 In these cases,
 .Va net.inet.ip.portrange.randomized
 can be used to toggle randomization off.
+If more than
+.Va net.inet.ip.portrange.randomcps
+ports have been allocated in the last second, then return to sequential
+port allocation.
+Return to random allocation only once the current port allocation rate
+drops below
+.Va net.inet.ip.portrange.randomcps
+for at least
+.Va net.inet.ip.portrange.randomtime
+seconds.
+The default values for
+.Va net.inet.ip.portrange.randomcps
+and
+.Va net.inet.ip.portrange.randomtime
+are 10 port allocations per second and 45 seconds correspondingly.
 .Ss "Multicast Options"
 .Pp
 .Tn IP
diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c
index efdab89..3ff8615 100644
--- a/sys/netinet/in_pcb.c
+++ b/sys/netinet/in_pcb.c
@@ -148,12 +148,14 @@ SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, reservedhigh,
 	   CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedhigh, 0, "");
 SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, reservedlow,
 	   CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedlow, 0, "");
-SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomized,
-	   CTLFLAG_RW, &ipport_randomized, 0, "");
-SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomcps,
-	   CTLFLAG_RW, &ipport_randomcps, 0, "");
-SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomtime,
-	   CTLFLAG_RW, &ipport_randomtime, 0, "");
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomized, CTLFLAG_RW,
+	   &ipport_randomized, 0, "Enable random port allocation");
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomcps, CTLFLAG_RW,
+	   &ipport_randomcps, 0, "Maximum number of random port "
+	   "allocations before switching to a sequental one");
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomtime, CTLFLAG_RW,
+	   &ipport_randomtime, 0, "Minimum time to keep sequental port "
+	   "allocation before switching to a random one");
 
 /*
  * in_pcb.c: manage the Protocol Control Blocks.
@@ -1211,7 +1213,8 @@ in_pcbsosetlabel(so)
  * allocation should be continued.  If more than ipport_randomcps
  * ports have been allocated in the last second, then we return to
  * sequential port allocation. We return to random allocation only
- * once we drop below ipport_randomcps for at least 5 seconds.
+ * once we drop below ipport_randomcps for at least ipport_randomtime
+ * seconds.
  */
 
 void