diff --git a/CHANGES b/CHANGES
index effcf1e8b1..7633bded32 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4109.	[port]		linux: support reading the local port range from
+			net.ipv4.ip_local_port_range. [RT # 39379]
+
 4108.	[func]		An additional NXDOMAIN redirect method (option
 			"nxdomain-redirect") has been added, allowing
 			redirection to a specified DNS namespace instead
diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index 012bcf6dd8..2dea1edc92 100644
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -488,6 +488,12 @@
 	  to be configured on the server is now available.
 	</para>
       </listitem>
+      <listitem>
+	<para>
+	  Retrieving the local port range from net.ipv4.ip_local_port_range
+	  on Linux is now supported.
+	</para>
+      </listitem>
     </itemizedlist>
   </sect2>
   <sect2 id="relnotes_bugs">
diff --git a/lib/isc/unix/net.c b/lib/isc/unix/net.c
index 0fa038885a..9bcd189225 100644
--- a/lib/isc/unix/net.c
+++ b/lib/isc/unix/net.c
@@ -778,12 +778,12 @@ getudpportrange_sysctl(int af, in_port_t *low, in_port_t *high) {
 		sysctlname_lowport = SYSCTL_V6PORTRANGE_LOW;
 		sysctlname_hiport = SYSCTL_V6PORTRANGE_HIGH;
 	}
-	portlen = sizeof(portlen);
+	portlen = sizeof(port_low);
 	if (sysctlbyname(sysctlname_lowport, &port_low, &portlen,
 			 NULL, 0) < 0) {
 		return (ISC_R_FAILURE);
 	}
-	portlen = sizeof(portlen);
+	portlen = sizeof(port_high);
 	if (sysctlbyname(sysctlname_hiport, &port_high, &portlen,
 			 NULL, 0) < 0) {
 		return (ISC_R_FAILURE);
@@ -817,12 +817,12 @@ getudpportrange_sysctl(int af, in_port_t *low, in_port_t *high) {
 		miblen = sizeof(mib_lo6) / sizeof(mib_lo6[0]);
 	}
 
-	portlen = sizeof(portlen);
+	portlen = sizeof(port_low);
 	if (sysctl(mib_lo, miblen, &port_low, &portlen, NULL, 0) < 0) {
 		return (ISC_R_FAILURE);
 	}
 
-	portlen = sizeof(portlen);
+	portlen = sizeof(port_high);
 	if (sysctl(mib_hi, miblen, &port_high, &portlen, NULL, 0) < 0) {
 		return (ISC_R_FAILURE);
 	}
@@ -841,11 +841,34 @@ getudpportrange_sysctl(int af, in_port_t *low, in_port_t *high) {
 isc_result_t
 isc_net_getudpportrange(int af, in_port_t *low, in_port_t *high) {
 	int result = ISC_R_FAILURE;
+#if !defined(USE_SYSCTL_PORTRANGE) && defined(__linux)
+	FILE *fp;
+#endif
 
 	REQUIRE(low != NULL && high != NULL);
 
 #if defined(USE_SYSCTL_PORTRANGE)
 	result = getudpportrange_sysctl(af, low, high);
+#elif defined(__linux)
+
+	UNUSED(af);
+
+	/*
+	 * Linux local ports are address family agnostic.
+	 */
+	fp = fopen("/proc/sys/net/ipv4/ip_local_port_range", "r");
+	if (fp != NULL) {
+		int n;
+		unsigned int l, h;
+
+		n = fscanf(fp, "%u %u", &l, &h);
+		if (n == 2 && (l & ~0xffff) == 0 && (h & ~0xffff) == 0) {
+			*low = l;
+			*high = h;
+			result = ISC_R_SUCCESS;
+		}
+		fclose(fp);
+	}
 #else
 	UNUSED(af);
 #endif