diff --git a/docs/config.md b/docs/config.md
index a7284884..16256a5b 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -546,5 +546,7 @@ Attribute | Description | Default
 `vlan-priority` | VLAN priority | 0 
 `length` | Layer 3 (IP + payload) traffic length (76 - 1500) | 128
 `pps` | Stream traffic rate in packets per second | 1 
+`source-ipv4-address` | Overwrite source IPv4 address (downstream only) | 
+`source-ipv6-address` | Overwrite source IPv6 address (downstream only) | 
 
 For L2TP downstream traffic the IPv4 TOS is applied to the outer IPv4 and inner IPv4 header. 
\ No newline at end of file
diff --git a/src/bbl_config.c b/src/bbl_config.c
index 09481f6f..900efdd6 100644
--- a/src/bbl_config.c
+++ b/src/bbl_config.c
@@ -319,6 +319,20 @@ json_parse_stream (json_t *stream, bbl_stream_config *stream_config) {
     } else {
         stream_config->pps = 1;
     }
+
+    if (json_unpack(stream, "{s:s}", "source-ipv4-address", &s) == 0) {
+        if(!inet_pton(AF_INET, s, &stream_config->ipv4_source_address)) {
+            fprintf(stderr, "JSON config error: Invalid value for stream->source-ipv4-address\n");
+            return false;
+        }
+    }
+
+    if (json_unpack(stream, "{s:s}", "source-ipv6-address", &s) == 0) {
+        if(!inet_pton(AF_INET6, s, &stream_config->ipv6_source_address)) {
+            fprintf(stderr, "JSON config error: Invalid value for stream->source-ipv6-address\n");
+            return false;
+        }
+    }
     return true;
 }
 
diff --git a/src/bbl_stream.c b/src/bbl_stream.c
index 6a9e1e6c..6aa3dc5d 100644
--- a/src/bbl_stream.c
+++ b/src/bbl_stream.c
@@ -285,7 +285,11 @@ bbl_stream_build_network_packet(bbl_stream *stream) {
             eth.type = ETH_TYPE_IPV4;
             eth.next = &ipv4;
             ipv4.dst = session->ip_address;
-            ipv4.src = ctx->op.network_if->ip;
+            if(stream->config->ipv4_source_address) {
+                ipv4.src = stream->config->ipv4_source_address;
+            } else {
+                ipv4.src = ctx->op.network_if->ip;
+            }
             ipv4.ttl = 64;
             ipv4.tos = config->priority;
             ipv4.protocol = PROTOCOL_IPV4_UDP;
@@ -299,7 +303,11 @@ bbl_stream_build_network_packet(bbl_stream *stream) {
             eth.type = ETH_TYPE_IPV6;
             eth.next = &ipv6;
             ipv6.dst = session->ipv6_address;
-            ipv6.src = ctx->op.network_if->ip6.address;
+            if(*(uint64_t*)stream->config->ipv6_source_address) {
+                ipv6.src = stream->config->ipv6_source_address;
+            } else {
+                ipv6.src = ctx->op.network_if->ip6.address;
+            }
             ipv6.ttl = 64;
             ipv6.tos = config->priority;
             ipv6.protocol = IPV6_NEXT_HEADER_UDP;
@@ -313,7 +321,11 @@ bbl_stream_build_network_packet(bbl_stream *stream) {
             eth.type = ETH_TYPE_IPV6;
             eth.next = &ipv6;
             ipv6.dst = session->delegated_ipv6_address;
-            ipv6.src = ctx->op.network_if->ip6.address;
+            if(*(uint64_t*)stream->config->ipv6_source_address) {
+                ipv6.src = stream->config->ipv6_source_address;
+            } else {
+                ipv6.src = ctx->op.network_if->ip6.address;
+            }
             ipv6.ttl = 64;
             ipv6.tos = config->priority;
             ipv6.protocol = IPV6_NEXT_HEADER_UDP;