I'm running WireShark on the latest version of Ubuntu and I can't seem to be able to capture traffic coming from other devices besides my own. I see a TON of SSDP packets but not much of anything else. Also, I notice that a lot of the packets seem to be encrypted because they have mostly characters that don't mean anything in them. I am positive that I have Promiscuous Mode turned on. Can anyone help with this? I just would like to see decrypted traffic on other devices (my Nexus tablet in particular).
Edit: I can see IP addresses of other devices, however I can't see any TCP packets for them. Only SSDP
If this is on a wired network, it might be switched.
If this is on a wireless network, you might have to capture in monitor mode.
In both of those cases, promiscuous mode won't be sufficient.
Related
I'm struggling to get an embedded platform with fairly standard IPV4 networking running. I have a working prototype which obtains an IP via DHCP without problem on a point to point connection (single cat5 cable) attached to a test laptop.
On my new hardware I get the link up but no DHCP request gets to the server (monitoring with wireshark). However what I do see, 100% repeatable, when those packets should be received, is a couple of ICMPv6 packets from the test laptop. This happens every time, there is no other activity on that link at any other time.
It seems to me that those packets are trying to tell me something, but what? Perhaps the DHCP request is going out but malformed for some reason?
(I can't post the actual packet from my phone, will make a copy and do so later.)
Seems to be something generated by the laptop when it sees the link comes up. Turned out to be unrelated to the issue I had (which was hardware related).
I was reading that in order to capture traffic for more than just my machine I need to put the nic into promiscuous mode. By default the nic seems to filter out the packets which are not meant for it.
My Question is : How come my nic even receive traffic that is not intended for it? Isn't my router supposed to route packets only to the computer for which it is meant?
Sorry - newbie here and this may be an absolute down votable question that I am asking.
I have heard that in case of wireless networks, the traffic takes multiple paths and the NIC combines these signals to form the original signal. So when a NIC sends something to the gateway it will send multiple signals and some if not all may even be captured by your packet sniffer.
Monitor mode also works like this
The short answer: It depends. :)
Wireshark Wiki: Ethernet capture setup should be of help to get you started.
I'm app developer from Korea.
Let me have one supposition.
There is one PC and one android tablet.
these devices are in same network.
(192.168.0.x ...same in C class)
My question is same as followings
"using PC, how can I find another device by the device's MAC address only?"
I know there are network protocols including UTP , TCP/IP ....
which one should I use ?
and What algorithm should I use?
Please Help.
Thank you so much for reading.
I would suggest just passively listening until the device sends a packet. As soon as you see a packet with that MAC address as its source, its source IP address will (most likely) be that devices IP address. The specifics of how you promiscuously monitor a network vary by operating system.
The most portable way to do it is probably to attempt to communicate with ever IP address in the subnet, checking the operating system's ARP table to see if you found the right MAC. This requires non-portable code only to pull the ARP table. It's unpleasant if you happen to find yourself on a /16 subnet -- that's over 65,000 IPs with broadcast traffic needed for each one of them.
There's probably a better way to solve your outer problem, whatever it is.
I have a small home network that I would like to analyze and capture the traffic on. What are my options for doing this? Ultimately, I would like to use a packet capture library, such as libpcap, to sniff the network in real-time as my router receives packets. I'm mainly interested in HTTP traffic. Thus far, when I run my program, I only seem to be able to see packets sourced or destined to my machine. Is there a way that I may inspect any traffic that travels through my wireless modem/router?
From the research I've done, it seems that the only way this is possible is through ARP poisoning or using a CISCO router that features Embedded Packet Capture.
Has anyone tried either of these and how successful were you? Are these my only options or is there something I may have overlooked?
Hi :) I think ARP poisoning and so on is not so easy to drop in.. ;) but you could start by trying one of the most famous network packets analyzer: Wireshark. Networking is very far to be easy.. :P but Wireshark will help you a lot and, btw, supports also libcap. Hope that helps :)
I'm trying to confirm a user a unplugged my embedded device from a network before performing some maintenance. I'm considering "ping"ing all IP address on my sub-net, but that sounds crude. Is there a broadcast/ARP method that might work better?
You can try a broadcast ping (this is from linux):
ping -b 255.255.255.255
Another option is to download Nmap and do a ping-scan.
You could use nmap. It's still crude, but at least it's using a tool designed to do it so you don't have to spend time on it.
If you can't get reliable link state information from your Ethernet device (which most chipsets should support these days, BTW...), sending an ARP request for each IP on your local subnet is a decent substitute. The overhead is minimal, and as soon as you get a single response, you can be sure you're still connected to a network.
The only possible problem I see here, is that if your device is on a /8 subnet, it can take quite a while to loop through all 4294967296 possible IPs. So, you may want to consider some optimization, such as only sending ARP requests for your default gateway, as well as all IPs currently in your ARP table.
If there's a peer you know you were connected to recently you could try pinging or arping that first. That could cut down on the traffic you're generating.
you could also run tcpdump -n to see what's active on the network too.
Not receiving any responses to ICMP pings or ARP requests is not a 100% guarantee that there's no network connection. For instances, there might be devices on the network that are firewalled off.
EDIT: May be you could access some lower-level information on your embedded device to check whether the network interface has its link up without actually sending any data.
Is there any chance that your device supports UPnP or Bonjour? Beside of the low-level protocols your should also have a look at these protocols which support some kind of plug-&-Play functionality. A UPnP device for example sends a message on the LAN before it is switched off (though, this doesn't help if it is just removed by unplugging it...).