I have a REST service running on Mac OS X, which im currently accessing using "localhost:8888" and "10.0.2.2:8888"
I want to access the same service from another computer which is in the same network.
I disabled the firewall also and I typed
nc -v 192.168.1.3 8888
and got the result as
nc: connectx to 192.168.1.3 port 8888 (tcp) failed: Connection refused
currently i use localhost (to access using java application) and 10.0.2.2 (to access using android application runs in the simulator) which both runs on the same machine which the server runs too.
I want to put the android application to my phone and give the machine ip addess ( because if i connect to internet via wifi, it'll be in the same local area network) i should be able to access my service runs on my machine.
can some one please tell me what im doing wrong here? Thank you
You can't access localhost from your front end code. It needs to refer to the server's name or address.
The localhost address should be 127.0.0.1, which is in the loopback range of addresses. Any address in the 127.0.0.0/8 block can never appear anywhere on any network, nor can any address in that block be used as a source or destination address outside a host. It is not possible for one host to access anything in that address range on another host.
The goes back at least as far as RFC 990, ASSIGNED NUMBERS:
The class A network number 127 is assigned the "loopback" function,
that is, a datagram sent by a higher level protocol to a network 127
address should loop back inside the host. No datagram "sent" to a
network 127 address should ever appear on any network anywhere.
RFC 1122, Requirements for Internet Hosts -- Communication Layers:
(g) { 127, }
Internal host loopback address. Addresses of this form MUST NOT
appear outside a host.
Also RFC 3330, Special-Use IPv4 Addresses:
127.0.0.0/8 - This block is assigned for use as the Internet host loopback address. A datagram sent by a higher level protocol to an
address anywhere within this block should loop back inside the host.
This is ordinarily implemented using only 127.0.0.1/32 for loopback,
but no addresses within this block should ever appear on any network
anywhere [RFC1700, page 5].
Related
My firm produces some devices with a network interface. The devices are sent with a IP address = 0.0.0.0. The customers plugs the device on the private net in the field and, by using a tiny app written with VB6, discover it and set the correct IP address.
This working by using UDP messages: the app broadcast a "Who's there?" UDP message, read back the answer(s) containing the MAC address of the device(s), and the the user send another UDP message containing the new IP address for target MAC.
Now, for some unknown reasons, one of these device get its IP address set to 127.0.0.2. The problem is that now the VB app can't find (via UDP) the device anymore, making it impossible to change the IP address to a valid one.
Further analisys revealed than if the app is running on Windows XP it sees the device, but if the app is running on Windows 7 the UDP message does'nt arrive to to the "socket" (while Wireshark can see the answer from the device).
Now, there a solution to allow Win7 to let "pass" an UDP message sent from a 127.0.0.2 external address? If yes, we could avoid to ship around the world a replacement device with a correct IP address and all the trouble of phisically mounting it in the field.
Here's a Wireshark capture of the "question" and the "answer" not "detected" by the VB app:
cap.pcapng
Now, for some unknown reasons, one of these device get its IP address set to 127.0.0.2.
You need to fix that.
The 127/8 block is reserved for the "loopback" address (ie. localhost). No packets sent to 127.0.0.2 will leave your systems NIC. Unless there are bugs in the drives (or hardware): this could be the case with WinXP.
app = require('http').createServer()
app.listen(5000, '75.113.126.31')
Error: listen EADDRNOTAVAIL
People say this error means I'm trying to listen on an IP address that I don't own. But that is my external IP address according to google.
Also, if I omit my IP, it only works when I visit localhost:5000 and 127.0.0.1:5000, visiting 75.113.126.31:5000 doesn't work, even though people say node should listen there too when I don't give a 2nd argument to listen. I also tried listening on IP 0.0.0.0 with no luck accessing it through external IP.
What are the possible causes? I disabled Windows firewall but that didn't help.
Your external IP and your computer's network address often have almost nothing in common. In fact it would be very unusual if they did match.
Normally you bind to 0.0.0.0 if you want your service to be available remotely.
It's also worth noting that if you have some kind of router or firewall you'll need to configure port mapping to get port 5000 to route to your local IP correctly.
ipconfig should show you your actual IP address.
You should also be aware that some routers don't handle mapping internal traffic back to a local IP. Many do, so it's not always a problem, but if it doesn't work that might be the case.
The error message you are getting is correct. I'm going to assume you are on a computer behind a router. That ip address Google is reporting is the ip address assigned to your router not your computer, i.e your computer doesn't own it. You can prove this by running the command ipconfig in a cmd prompt, finding out your eth/wifi ip address, and using that in your app.listen (it'll probably start with 192 or 10), it should work. If you want to make your app public an easier way might be to just forward the port 5000 from your router the computer running the node app. Hope this helps!
Is it possible that set a proxy for windows (7) and all packets go Through the proxy server ? I mean all packets even ARP packets !
Sure it is take a look at arp spoofing/poisoning basically arp protocol works by machine saying this is my IP address and the router takes note and forwards any packets with this IP to that machine (Mac Address). SO basically you have to send out the arp messages at a faster rate tricking the router that messages should be bound to your machine and not the actual mac address that IP should belong to.
just to note (arp is a LAN protocol) so if your proxy is not within the the subnet as the machine your presumably attacking their is no way you can get these packets
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.
Imagine a Windows box, which:
hosts a WCF service
has multiple NICs
sits behind NAT
When a user issues a request to the service (on top of the WCF infrastructure), he uses the external address assigned to the target machine by the NAT.
I have to write some piece of code inside the WCF service, which must know which of the several NICs that the machine has was used to actually handle the network traffic. How does this code identify the NIC is less important - it could be its MAC address (the best) or it could be the (internal) IP address of the NIC.
How can I do it?
EDIT1
I will try to supply the question context. There are two agents. Both expose the same WCF service. In addition, one of the agents can be instructed to start probing the network towards the second agent in the following fashion:
Agent A is asked to probe the network to agent B
Agent A negotiates with agent B the UDP port to utilize for the sake of probing using the WCF service exposed by the agent B.
Once negotiation is over, the agent A starts some custom protocol over UDP, where the agent B acts as the server - i.e. it binds to the UDP port negotiated in the previous item.
Binding to a UDP port requires two pieces - the IP address and UDP port, where the IP address can either be a specific IP address or * (to bind to all the IP addresses associated with the machine). The latter option is not good for us - I will omit the reasons. This leaves us the former option - binding to the specific IP address. However, when the agent B is behind NAT, the IP address used to talk to the WCF service is the external IP address assigned to the agent by the NAT. Binding, on the other hand, requires the respective internal IP address - how to get it?
Can you check the OperationContext.Current.Channel.LocalAddress (it's an EndpointAddress) inside a WCF operation?
As a side note, getting the remote address can be done with:
OperationContext context = OperationContext.Current;
MessageProperties prop = context.IncomingMessageProperties;
RemoteEndpointMessageProperty endpoint =
prop[RemoteEndpointMessageProperty.Name] as RemoteEndpointMessageProperty;
string ip = endpoint.Address;
--larsw
To get the MAC use
System.Net.NetworkInformation.NetworkInterface.GetPhysicalAddress();
All Nics:
System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces();
to find out what is the real listening ip address you can write a code that listen to your port on each address and ping it from an agent emulator to see that the address is valid.
Cheers,
Gilad