I have an application that is designed and working that is receiving UDP broadcasts on a port. The application has been working just fine, but I have wanted to compare the packets received by the application with a Wireshark capture. I'm trying to make sure that I'm capturing as many of the packets as possible with minimal data loss.
I initially thought that I'd run Wireshark and compare the raw packets captured against the packets shown in our application. However, when I run Wireshark, the packets are never captured at the IP layer for that port. I see other traffic from the server, but I never see Wireshare packets for this specific port.
The application continues to capture the data just fine. When I look at the IP src/dest fields, the src looks correct, 10.12.10.42, however the destination IP address is 0.0.0.0. I would have expected something like 255.255.255.255 instead for the destination address.
I don't have access to the application that is broadcasting the data, but I did write a quick sample UDP broadcaster and receiver to make sure I my expectations were correct. the sample application worked as expected.
Any ideas on why a UDP broadcast would be received by an application, but not show up in a Wireshark capture? Does Wireshark ignore an address like 0.0.0.0 and not capture it all?
Wireshark only captures Ethernet frames that are going through an interface you are listening on. Thus, packets destined on loopback addresses are not captured. I would check your machine's routing tables to see where packets are actually going.
Related
I am trying to ping a host and capture the packets using Wireshark. I need to view the results in ICMP so I can view the IP addresses, but Wireshark keeps capturing the packets in ICMPv6 and as a result I can only see MAC addresses. Is there a way to change that?
I've tried looking in the options of my capture interfaces and didn't really find anything helpful. I'm not sure if it's a Wireshark issue or an issue with my system.
i'm trying to do the following:
a) Set Contiki in Promiscuous Mode.
b) Then retrieve all UDP and RPL packets send, not only to current node but also between two other nodes within communication range.
I have the following code:
NETSTACK_RADIO.set_value(RADIO_PARAM_RX_MODE, 0);
simple_udp_register(&unicast_connection, 3001,
NULL, 3000, receiver);
where receiver is an appropriate callback function. I am able to collect UDP packets send to the current node, but still unable to receive packets send between other nodes in my communication range.
Setting the RADIO_PARAM_RX_MODE only controls which packets the radio driver filters out. There are multiple layers in an OS network stack, of which the radio driver is only the first one. The next ones are RDC and MAC, which still filter out packets addressed to other nodes, and there is no API to disable that.
The solution is to either modify the MAC to disable dropping of packets not addressed to the local mode or write your own simple MAC. The latter is what the Sensniff (Contiki packet sniffer) does - see its README and source code. By the way, if you just want to log all received packets, just use Sensniff!
When I enable Wireshark capture on my laptop, the application becomes slow because it captures all the packets. I am running about 100 Mbps of traffic with different packet sizes.
Let's say, I only need to capture rtp,sip packets and ignore the other UDP, TCP, DHCP etc.
How can I do it using Wireshark?
Note: I know the filter option to view only the packets I need, but the request is to only capture rtp packets
From the Wireshark SIP wiki page:
Capture Filter
You cannot directly filter SIP protocols while capturing. However, if you know the UDP or TCP or port used (see above), you can filter on that one.
For help with writing capture filters, refer to the pcap-filter man page.
I am a complete novice to this... I have a webcam behind my router, and it's configured to be accessible on a particular port (e.g. 30000) using a port forwarding configuration. It has a fixed IP in my network.
Using wireshark, I can see the camera responding to requests coming from within my network (i.e. another client), and this does not use port forwarding.
However, when I access the camera from outside my network (i.e. using external IP plus port), wireshark does not show anything (but I see the camera streaming on the client).
I use wireshark on ubuntu, eth0, and ip.addr == 192.168.x.y as filter
When the camera was streaming data to the internal client, were you also capturing packets with Wireshark on that same client? I'm guessing that you were, which is why you saw the data.
When the camera streams to a client on an external network, the stream flows through the router, but your client is likely plugged into another switch port on the back of your router, and the router doesn't forward the packets to that port, which is why you don't see them.
In order to observe the packets, you would need to configure your capture PC such that it can capture the packets. There are a few different methods to achieve this, for example, using a hub, a SPAN/mirror port on a managed switch if you have one, or a TAP. I would recommend reading the detailed information available on the Wireshark Ethernet capture setup wiki page, which describes several different methods for successfully capturing Ethernet frames and provides helpful pictures as well. Choose a capture scenario that best meets your needs (and $$ budget).
How can I use wireshark to capture all the packets destined to the router. I want to run wireshark on the router. Is this possible?
No, it's not possible to run wireshark on the router.
What you can do, however, is run wireshark on one of the computers in the network in sniffer/monitor mode and filter out all the packets with destination address set to address of the router. Note, if you want to capture also the wired packets to your router, this won't work.