[PATCH v1] dts: only sniff inbound packets

[PATCH v1] dts: only sniff inbound packets

[Patrick Robb]

Add a filter to the Scapy traffic generator sniffer which
forces the sniffer to ignore outbound traffic, preventing
double counting of packets. Without this change sniffing
will double count packets when DTS is being run with a
single link topology, because the Scapy packet transmission
and Scapy sniffing is happening on the same port. The
correct behavior is to only count inbound traffic which is
being returned to the traffic generator by the DTS SUT.

Fixes: dfb667368077 ("dts: add Scapy asynchronous sniffer")

Signed-off-by: Patrick Robb <probb@iol.unh.edu>
---
 dts/framework/testbed_model/traffic_generator/scapy.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dts/framework/testbed_model/traffic_generator/scapy.py b/dts/framework/testbed_model/traffic_generator/scapy.py
index 9e15a31c00..c6e9006205 100644
--- a/dts/framework/testbed_model/traffic_generator/scapy.py
+++ b/dts/framework/testbed_model/traffic_generator/scapy.py
@@ -203,7 +203,7 @@ def _sniff(self, recv_port: Port) -> None:
         ready_prompt = "Ready."
         self.send_command(
             "sniff("
-            f'iface="{recv_port.logical_name}", quiet=True, store=False, '
+            f'iface="{recv_port.logical_name}", filter="inbound", quiet=True, store=False, '
             "prn=lambda p: bytes_base64(p.build()).decode(), "
             f'started_callback=lambda: print("{ready_prompt}")'
             ")",
-- 
2.49.0

Re: [PATCH v1] dts: only sniff inbound packets

[Andrew Bailey]

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Tested-by: Andrew Bailey <abailey@iol.unh.edu>
Reviewed-by: Andrew Bailey <abailey@iol.unh.edu>

On Tue, Mar 10, 2026 at 1:13 PM Patrick Robb <probb@iol.unh.edu> wrote:

> Add a filter to the Scapy traffic generator sniffer which
> forces the sniffer to ignore outbound traffic, preventing
> double counting of packets. Without this change sniffing
> will double count packets when DTS is being run with a
> single link topology, because the Scapy packet transmission
> and Scapy sniffing is happening on the same port. The
> correct behavior is to only count inbound traffic which is
> being returned to the traffic generator by the DTS SUT.
>
> Fixes: dfb667368077 ("dts: add Scapy asynchronous sniffer")
>
> Signed-off-by: Patrick Robb <probb@iol.unh.edu>
> ---
>  dts/framework/testbed_model/traffic_generator/scapy.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/dts/framework/testbed_model/traffic_generator/scapy.py
> b/dts/framework/testbed_model/traffic_generator/scapy.py
> index 9e15a31c00..c6e9006205 100644
> --- a/dts/framework/testbed_model/traffic_generator/scapy.py
> +++ b/dts/framework/testbed_model/traffic_generator/scapy.py
> @@ -203,7 +203,7 @@ def _sniff(self, recv_port: Port) -> None:
>          ready_prompt = "Ready."
>          self.send_command(
>              "sniff("
> -            f'iface="{recv_port.logical_name}", quiet=True, store=False, '
> +            f'iface="{recv_port.logical_name}", filter="inbound",
> quiet=True, store=False, '
>              "prn=lambda p: bytes_base64(p.build()).decode(), "
>              f'started_callback=lambda: print("{ready_prompt}")'
>              ")",
> --
> 2.49.0
>
>

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Re: [PATCH v1] dts: only sniff inbound packets

[Luca Vizzarro]

Reviewed-by: Luca Vizzarro <luca.vizzarro@arm.com>