I'm trying to get MAC address of devices connected in my subnet.
For that, I send a ping request and read ARP table in the NIC (under Windows : arp -a)
I'm trying to mimic this behavior in a ESP32-POE module from Olimex with LAN8720 NIC.
I can do the trick on a W5500 NIC with : W5500.readSnDHAR(i,destMac);
How can I achieve that on ESP32-POE/LAN8720 ? (Arduino or ESP-IDF)
Related
I have a specialised hardware which is configured to communicate to a single IP address. But I want to communicate with 2 servers for SQL Server Availability Group(Both are Replicas to each other), So I make a cluster of 2 Servers (Windows Server).
For Example :
IP Address of Server 1 : 185.178.94.2
IP Address of Server 2 : 185.178.94.3
Cluster/Listener IP Address : 185.178.94.5
The Problem now is when hardware(Configured to communicate to 185.178.94.5) is sending ARP Request (i.e. asking MAC address of 185.178.94.5), the response is going from the correct server but it is going like this 185.178.94.2 has MAC address ae:23:dc:4r:2w:5r instead of going like 185.178.94.5 has MAC address ae:23:dc:4r:2w:5r.
The arp table of hardware now has entry
185.178.94.2 --- ae:23:dc:4r:2w:5r
instead of
185.178.94.5 --- ae:23:dc:4r:2w:5r
The same setup working fine if we use a normal laptop instead of our specialised hardware.
One more thing I would like to mention here is in case of hardware , if we remove LAN cable from one of the server, then packets starts coming and the arp table of hardware updated with an entry for 185.178.94.5.
I am building a Mini-Project and I came across this problem..I have to find MAC Addresses of all Devices that were in my Home Network .Here I got all the devices local IP addresses (I pinged from 1 to 255 and noted down all responded devices IP's).Here i am using Windows with python 2.7.x .I do also need the Network Card Manufacturer Name.
In other words I just want the raw data that the WI-FI Watcher shows.
My aim to get MAC and Network Card Manufacturer Name
First of all please make sure you ping all the hosts in your subnet. I would ping the broadcast address first, then just in case all of them, maybe some of them did not respond to your broadcast.
This way you will fill the local ARP cache of your machine. Then you can run this executable:
arp -a -v
Which will output information on all the IP addresses and their corresponding MAC address.
Then it's just a matter of looking up the OUI of the MAC address.
In pure python, as you mention in your comment, you can use "Scapy". you can find an ARP ping example here:
https://freezion.com/2009/01/22/arp-ping-using-scapy/
Basically:
from scapy import srp,Ether,ARP,conf
conf.verb=0
ans,unans=srp(Ether(dst="ff:ff:ff:ff:ff:ff")/ARP(pdst=sys.argv[1]),
timeout=2)
For OUI lookup, you can use this small bit of code, although it has an external dependency:
import requests
for addr in ['88:53:2E:67:07:BE', 'FC:FB:FB:01:FA:21',
'D4:F4:6F:C9:EF:8D', '23:45:67']:
vendor = requests.get('http://api.macvendors.com/' + addr).text
print(addr, vendor)
Also, you can try the OUI parser lib from Wireshark.
NOTE: this does not work if ICMP is disabled on the destination hosts, in that case you have to run a traditional portscan and find open ports.
My MAC is connected to Ethernet and Wifi at a time. Both are different networks. I wanted to know from which interface my system is accessing internet. I want a command to check this. By giving
traceroute google.com , i can get default route, as i know ip addresses of both networks. But the case is how can i detect this in remote machines whose ip addresses are unknown
when i give
ifconfig
I see en0 and en1 are assigned with two diff ips and are active. Even from this i am unable to differentiate.
I achieved this by following below procedure
1) networksetup -listnetworkserviceorder , by using this we will network service order of MAC, along with interface to which it is connected
2) route get default | grep interface gives the currently using interface.
By checking current interface with service order, we can know from which interface our mac is accessing internet
I need to findout the mac address of the device from which my device gets TCP requests, I ll be getting the ip address of the device by tcp endpoint but i need to find out the mac address of the device.My application will be running on both windows and linux, so please suggest me a cross platform method to find the mac address.. Any boost libraries will help me doing the same??
Firstly, you can't find the MAC address for any network interface that is not on the same local area network. That information is not transmitted beyond the router.
There is a command line tool called arp that is available on Unix and also Windows that will list IP addresses and MAC addresses of interfaces that have been in communication with your PC. i.e.
arp -a
on Windows gives something like:
Interface: 9.175.198.236 --- 0x2
Internet Address Physical Address Type
9.175.198.129 00-1b-53-46-fa-7f dynamic
and on a Unix-alike looks like:
foo.bar.com (10.27.68.72) at 00:50:56:AE:00:0B [ether] on eth0
baz.bar.com (10.27.68.77) at 00:50:56:AE:00:10 [ether] on eth0
? (10.27.68.1) at 00:50:5A:1B:44:01 [ether] on eth0
You can try invoking it and parsing the output programmatically.
arp source code is available in the below link, take the piece of code that interests you! It is c code so it should work fine.
http://www.opensource.apple.com/source/network_cmds/network_cmds-328/arp.tproj/arp.c
First thing to note is that at TCP layer, you don't know the MAC addresses.
For your case, I guess you can do two things:
use arp or write a piece of code similar to arp which looks for MAC given the IP address.
The problem with this approach is that it won't work in cases when the source is in another network.
write your server in such a way that it requests for this information from the client sending TCP request. This can be done post TCP establishment. The client should also be able to look up the machine's MAC address for the given IP.
Is there a way to find out the IP address of a device that is directly connected to a specific ethernet interface? I.e. given one host, one wired ethernet connection and one second host connected to this wired connection, which layer or protocol below IP could be used to find this out.
I would also be comfortable with a Windows-only solution using some Windows-API function or callback.
(I know that the real way to do this would probably via DHCP, but this is about discovering a legacy device.)
Mmh ... there are many ways.
I answer another network discovery question, and I write a little getting started.
Some tcpip stacks reply to icmp broadcasts.
So you can try a PING to your network broadcast address.
For example, you have ip 192.168.1.1 and subnet 255.255.255.0
ping 192.168.1.255
stop the ping after 5 seconds
watch the devices replies : arp -a
Note : on step 3. you get the lists of the MAC-to-IP cached entries, so there are also the hosts in your subnet you exchange data to in the last minutes, even if they don't reply to icmp_get.
Note (2) : now I am on linux. I am not sure, but it can be windows doesn't reply to icm_get via broadcast.
Is it the only one device attached to your pc ?
Is it a router or another simple pc ?
To use DHCP, you'd have to run a DHCP server on the primary and a client on the secondary; the primary could then query the server to find out what address it handed out. Probably overkill.
I can't help you with Windows directly. On Unix, the "arp" command will tell you what IP addresses are known to be attached to the local ethernet segment. Windows will have this same information (since it's a core part of the IP/Ethernet interface) but I don't know how you get at it.
Of course, the networking stack will only know about the other host if it has previously seen traffic from it. You may have to first send a broadcast packet on the interface to elicit some sort of response and thus populate the local ARP table.
Windows 7 has the arp command within it.
arp -a should show you the static and dynamic type interfaces connected to your system.
Your Best Approach is to install Wireshark, reboot the device wait for the TCP/UDP stream , broadcasts will announce the IP address for both Ethernet ports
This is especially useful when the device connected does not have DHCP Client enabled, then you can go from there.
You can also get information from directly connected networking devices, such as network switches with LDWin, a portable and free Windows program published on github:
http://www.sysadmit.com/2016/11/windows-como-saber-la-ip-del-switch-al-que-estoy-conectado.html
LDWin supports the following methods of link discovery: CDP (Cisco Discovery Protocol) and LLDP (Link Layer Discovery Protocol).
You can obtain the model, management IP, VLAN identifier, Port identifier, firmware version, etc.