How do I know visitor's MAC address on linux hosting (nginx)?
From ethernet user.
Thanks.
You cannot get that through PHP.
Networks protocol are used in a stack. When doing HTTP communications, your web server uses the HTTP protocol, responsible for the high-level communications. This protocol is implemented on the top of the TCP protocol (which brings stream-like connections and port numbers), which in turn is implemented on the top of the IP protocol (v4 or v6, which bring IP addresses for identification), which in turn is implemented on the top of the Ethernet protocol.
The Ethernet protocol is the one you would need to work with. It has both the source MAC address and the destination MAC address. However, most unfortunately, there are a lot of problems with it.
First, the data it conveys is probably hard to access: I say "probably" because I never stumbled upon how to do it.
Second, much like you get your client's router address when they access your site, you get your client's router MAC address at the Ethernet level. Unless they don't traverse any router (which would only happen if your server was directly wired to your client machine without any router interfering, because there are a whole lot of routers out there that relay data to other parts of the Internet), there is no chance that the MAC address you'll receive will be your client's.
Third, Apache will never try to access that data. And since PHP is "sandboxed" into the network environment Apache gives it, there is no way you can wind back to the Ethernet protocol.
So accessing the MAC address of a visitor from a website, from PHP, is not possible.
EDIT Seems you've taken out the PHP part from your question. So obviously, the last point won't stand anymore.
You can't get that with php it's not included in http
The more general question is this one. Since all PHP has to work with (I'm assuming this is PHP running on your webserver, here) is the HTTP request, you won't be able to get the MAC address. That requires something running on the visitor's side.
This may, or may not work. I know it will work on LAN clients, however for external clients it may be incorrect. I don't overly know my networking, but it's worth a shot right?
If you execute the arp -a command on either windows or linux, it will print out your arp records, which you can then parse for the mac.
Other than that, as far as I know, apache (and therefor php) doesn't just give out mac addresses in its env vars.
*Edited: Sorry, that won't work... The better utility is arping however that will just give you the mac of your router.
If you want to do this, clients will need to be directly connected to your server, with no router in between...
However if that is the case, then arping will work... I don't know of a better tool, but it seems a bit wasteful to do a ping (in root) for just a mac address.
The mac address is only visible on for the network provider if i'm correct (your internet host can see the mac address of your router for example), don't think you can get it with php.
Related
Sorry for asking such a mundane question, but I'm suddenly curious. If I open the network connections dialog on my Windows machine, it shows me a cute little picture of my computer connecting to a router and then to a globe (labeled Internet). What is Windows trying to connect to in order for it to decide that the computer has Internet connectivity? I assume there is no IP4 address for 'The Internet', so where is it going? Is it just sending a ping to an address back at the Microsoft home office? If that address were to disappear, would my window's machine suddenly decide that it no longer has a route to the Internet? Would Windows boxes that were 'close' to that address incorrectly report that they could get to the Internet when they couldn't.
I'll stop now before this gets too silly. But seriously, what criteria does a Windows box use to determine that it has Internet connectivity? I'm assuming that Linux and iOS systems have an equivalent feature. Do they use the same criteria?
The general IP address that is used for 'the internet' is 8.8.8.8 - or Google.com.
If you can ping it, and get a web page from it, then there's a pretty good chance you can get to at least some of the internet.
But for specifically Windows - Network Connectivity Status Indicator - it uses a different domain: dns.msftncsi.com
It will (unless disabled by GPO):
resolve the name, and verify it has the 'right' IP (131.107.255.255
fd3e:4f5a:5b81::1 )
Perform a HTTP get to this address and check it gets a result. NCSI
Presumably if different responses are retrieved, then it can tell if it has a wi-fi login or similar.
Your intuitions seem correct. I am not on a Windows machine but you could find out by firing netstat and then connecting.
If I was programming this I'd make Ping, TCP and HTTP requests. Some devices are connected through proxies such as firewalls, captive portals and others. the only way to be sure is to send something and receive a reply.
My Android device for example can detect captive portals. It probably does that by trying to HTTP connect somewhere.
We have a product that runs Windows XP Embedded SP1. We configure a fake (does not exist) MAC address for a fake IP in the ARP table. When there is a communication happening, Windows sends packets to the fake MAC and fakeIP and later we change it to real ones in a driver.
This is how the software is designed.
The problem is that sometimes Windows starts sending ARP requests for the fake IP even though it has an entry for it in the ARP table. I had no clue why this was happening and, in blind attempt to reproduce the issue, I wrote a script to delete ARP entry then add it again after some seconds. After some attempts, I saw the problem happening.
Any ideas about what should I check/change?
Can you Check the Ethernet Frame MAC Addresses in both cases, in the case where there is an entry and when there is no entry in the arp cache.
Additionally, Check your code, I think you will find some reference to the FAKE IP address inside your code (that you might have forgot to change)
There are many application layer protocols that require the use of ARP prior to their commmunication, So I think maybe you're using one of these protocols in your code and you instruct the code to communicate with the fake IP address, that's why when you invoke this protocol it uses arp to find the mac address of the fake IP.
Let me know if this answers your question.
One of my real weak points in programming is networking, so I admit that I may be a little over my head with this project. Please feel free to tell me if what I'm trying to do doesn't make any sense
What I am trying to do, basically, is run a program on my laptop (Node.JS, probably) that handles requests from a website, does some functions, and serves data back to a client running on the website. (Research tells me this is called an RPC server)
When you listen for requests in Node.JS, you specify a port and optionally an IP Address- localhost, 127.0.0.1, is what all the tutorials I've read have used, but that's not sufficient for what I'm trying to do
I've read that I'll need to set up a static IP Address? But I think those are relative to my LAN, so they'll be like 192.168.0.X. So then what would I specify for the IP for the server and the client? (I don't think the port particularly matters). Do I need a DNS?
I hope this makes sense, sorry for so many questions, thank you for your help
You can run a server on your local machine, and you will specify your local IP address for the script, like 192.168.0.x. But for this server to ever receive a connection, your client must connect to your external IP address. It is the IP address that you get from your Internet provider when you connect to Internet. If your external IP is static, i.e. it does not change, then you can use it in your client script. If the external IP changes, you must setup a DNS record that would resolve the name of your computer. DynDNS can be used for that purpose.
If you have a router, it must be setup so that it forwards connections to your laptop where the server runs. And your firewall must be configured to allow connections.
I often run into problems where I can't get something to connect to something else. I usually forget to check something obvious. Can you help with:
A tip/technique for diagnosing a connection issue
The name of a tool or application that can help (and the situation in which it's useful)
I know the question is a little non-specific, but hopefully the answers can form a useful starting point for anybody who's stuck trying to get computers/programs talking to each other.
Please can you give one answer per answer so the best ones can be voted up.
Simple checks to run when debugging network problems:
Has each machine got an IP address, Go to command prompt and run ipconfig. Key things to check here are the interfaces and ensuring the appropriate ones have IP addresses.
Check both machines IP addresses are in the same range and subnet if you are running it on an internal or Virtual network.
Try pinging each machine from the other to see if they can communicate with each other. Note that some firewalls will block ping requests.
If Pinging fails then check to see if firewalls are active. If the communication is within a 'safe' internal network then try disabling the firewalls and re-pinging.
If the connections are over a wireless network then check signal strength.
If pinging fails and you are connecting through several networks then try running a tracert to see at which will may show you where on the network the connection is failing.
If you are able to ping but not connect then check firewall settings and network connection settings. Windows 2000+ has the capability of setting port an ip access on a connection properties.
Try drawing a network diagram of the connections to help in visualising the problem.
If you are connecting through routers, firewalls and loadbalancers then check that all devices are not tied to any specific ip addresses and that the IP address redirection (if in place) is correct. Also check any NAT logs to see if connections are being received and properly re-directed.
Wireshark
Latest versions of ProcMon
netstat
Wireshark www.wireshark.org
Wireshark is a network protocol analyzer for Unix and Windows.
Features:
Deep inspection of hundreds of protocols, with more being added all the time
Live capture and offline analysis
Standard three-pane packet browser
Multi-platform: Runs on Windows, Linux, OS X, Solaris, FreeBSD, NetBSD, and many others
Captured network data can be browsed via a GUI, or via the TTY-mode TShark utility
The most powerful display filters in the industry
Rich VoIP analysis
Read/write many different capture file formats: tcpdump (libpcap), Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer® (compressed and uncompressed), Sniffer® Pro, and NetXray®, Network Instruments Observer, Novell LANalyzer, RADCOM WAN/LAN Analyzer, Shomiti/Finisar Surveyor, Tektronix K12xx, Visual Networks Visual UpTime, WildPackets EtherPeek/TokenPeek/AiroPeek, and many others
Capture files compressed with gzip can be decompressed on the fly
Live data can be read from Ethernet, IEEE 802.11, PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others (depending on your platfrom)
Decryption support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2
Coloring rules can be applied to the packet list for quick, intuitive analysis
Output can be exported to XML, PostScript®, CSV, or plain text.
work the OSI model from the bottom up
Physical (Do you have a network adapter/connection)
Link layer (arp, ethernet port blocked by network team (I've seen this where locked down environments see two MAC addresses coming from one workstation port and shut down the port)
Network layer (ipconfig, tracert, ping,)
Do you have a network address (DHCP, fixed)
Are you on a proper subnet/have routing between subnets
Is something in the middle blocking you
firewalls, routing tables
When in doubt, check to see if the windows firewall is messing with your communications. 8 times out of 10, it's at fault.
Using tracert is a good start to see how far along the chain you are getting.
For virtual machines it's usally a good idea to make sure you have the loopback adapter set correctly in the Host os.
Most frequently used tool is the ping. It can be used both to test your connection and the availability of a target
Second tool is the tracert if you want to see where the packets get lost.
For more advanced debugging I use the following tools: nmap, wireshark, etc.
Windows has a netstat utility which is pretty similar to the Unix netstat and can do a number of different things that might help you solve network issues.
Random example:
netstat -r displays routing information
netstat /? for usage information
Since you said you're using 2 virtual machines I would hazard a guess that both machines are setup in a NAT configuration (rather than a unique network device) -- In the NAT configuration, neither machine would (typically) be able to ping the other.
If you're familiar with the command line, you can try the "netstat" command.
You can also try "arp -a" to list all the IP/MAC addresses known to your PC.
The "tracert [ip address]" command will show you how many gateways/routers your packets jump through on their way to their destination. (This is probably not helpful if both machines are on the same network, though.)
And don't forget to check your Windows firewall settings.
Otherwise, if you want to get down and dirty, you can try the packet sniffer known as Wireshark: http://www.wireshark.org/ (aka. Ethereal)
Pull the network cable out
If you can get some communications to a device (eg a ping), but can't get your program to talk to a service on the computer. Then, try pulling the network cable out and see if the ping stops. This will verify you're communicating with the computer you really think you are.
On windows i user PortQueryUI : http://www.microsoft.com/en-us/download/details.aspx?id=24009
DNS activity: Portable DNS Cache and Firewall;
General network activity: Wireshark, Network Monitor;
Windows utilities: ping, netstat, nslookup.
You need to be use the process of elimination, for example if you can ping the ip address but not the hostname then there's DNS issues. If you can ping the system but not connect to a share etc.
DNS out of sync
If you're using a virtual machine and you perform a roll-back on it, then it could become out of sync with the DNS (Domain name server). Try to remove and re-add the machine to the domain, or if you've got access to the DNS machine, then get it to flush its cache.
Consider the following setup:
A windows PC with a LAN interface and a WiFi interface (the standard for any new laptop). Each of the interfaces might be connected or disconnected from a network. I need a way to determine which one of the adapters is the one connected to the internet - specifically, in case they are both connected to different networks, one with connection to the internet and one without.
My current solution involves using IPHelper's "GetBestInterface" function and supplying it with the IP address "0.0.0.0".
Do you have any other solutions you might suggest to this problem?
Following some of the answers, let me elaborate:
I need this because I have a product that has to choose which adapter to bind to. I have no way of controlling the setup of the network or the host where the product will run and so I need a solution that is as robust as possible, with as few assumptions as possible.
I need to do this in code, since this is part of a product.
#Chris Upchurch: This makes me dependent on google.com being up (usually not a problem) and on any personal firewall that might be installed to allow pinging.
#Till: Like Steve Moon said, relying on the adapter's address is kind of risky because you make a lot of assumptions on the internal network setup.
#Steve Moon: Looking at the routing table sounds like a good idea, but instead of applying the routing logic myself, I am trying to use "GetBestInterface" as described above. I believe what it should do is exactly what you outlined in your answer, but I am not really sure. The reason I'm reluctant to implement my own "routing logic" is that there's a better chance that I'll get it wrong than if I use a library/API written and tested by more "hard-core" network people.
Technically, there is no "connected to the Internet". The real question is, which interface is routeable to a desired address. Right now, you're querying for the "default route" - the one that applies if no specific route to destination exists. But, you're ignoring any specific routes.
Fortunately, for 99.9% of home users, that'll do the trick. They're not likely to have much of a routing table, and GetBestInterface will automatically prefer wired over wireless - so you should be good. Throw in an override option for the .1% of cases you screw up, and call it a day.
But, for corporate use, you should be using GetBestInterface for a specific destination - otherwise, you'll have issues if someone is on the same LAN as your destination (which means you should take the "internal" interface, not the "external") or has a specific route to your destination (my internal network could peer with your destination's network, for instance).
Then again, I'm not sure what you plan to do with this adapter "connected to the Internet", so it might not be a big deal.
Apparently, in Vista there are new interfaces that enable querying for internet connectivity and more. Take a look at the NLM Interfaces and specifically at INetworkConnection - you can specifically query if the network connection has internet connectivity using the GetConnectivity method.
See also: Network Awareness on Windows Vista
Unfortunately, this is only available on Vista, so for XP I'd have to keep my original heuristic.
I'd look at the routing table. Whichever NIC has an 0.0.0.0 route AND is enabled AND has the lowest metric, is the nic that's currently sending packets to the internet.
So in my case, the top one is the 'internet nic'.
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.0.0.10 10.0.0.51 20
0.0.0.0 0.0.0.0 10.0.0.10 10.0.0.50 25
(much other stuff deleted)
Another alternative is to ping or GetBestInterface 4.2.2.2 - this is an old and venerable DNS server, currently held by GTEI; formerly by Sprint if I remember right.
Start > Run > cmd.exe (this works in XP and Vista): ipconfig /all
This displays all info about the interfaces in your computer. The "public" facing interface should have a public IP address. For starters, it should not be 192.168.x.x or 10.x.x.x :)
running traceroute to some public site will show you. Of course, there may be more than one interface that would get you there.
Look at the routing table? Generally, unless you're routing between the networks in windows (which is possible, but unusual for a client computer these days) the interface that holds the default route is going to have the Internet connection.
Your question didn't detail why or what you're doing this with so I can't provide any specifics. The command line tool "route" may be of some help, but there are probably libraries for whatever programming language you're using to look at the routing table.
You can't rely on the IP address of the interface (e.g., assuming an RFC-1918 address [192.168.0.0/16, 172.16.0.0/12, 10.0.0.0/8] isn't the internet) since most sites have some kind of NATed firewall or proxy setup and the "internet" interface is really on a "private" lan that gets you out to the Internet.
UPDATE: Based on your further information, it sounds like you have a decent solution. I'm not so sure about the choice of 0.0.0.0 since that's a boundary case for IP address -- might be OK on your particular mix of platform/language. Sounds (from the API description) like you could just specify an address, so why not some address known to be on the Internet, e.g. the IP address of your web site, or something more random like 65.66.67.68? Just make sure not to pick one of the rfc-1918 addresses, or the localhost range (127.0.0.0/8), or multicast, any other reserved range, and any address that resolves to a .mil or .gov (while it doesn't sound like getbestinterface sends any traffic, it would suck to find out by having the feds break your door down... :)
Looking at the network point of view, either could be routing to the "internet" at any time. If things like spanning tree protocol are enabled on a switch then you may find that what may have been the routing card to begin with may not be anymore.
Ping google.com though each NIC.