I'm writing a website where the server is on a pi running a C program using libwebsockets. I'm wondering if it's possible to determine if the host is local (connected from LAN) or remote (from WAN). I'd like to limit what the web page can do if it's from a remote source.
You can use the lws_get_peer_simple function to obtain the IP address:
char name[16];
lws_get_peer_simple(wsi,name,16);
From there, it should be easy to determine if the IP address is in local subnets. One way to do it is by simple string comparisons:
if(strstr(name,"10.")==name)return(LOCAL_NET);
if(strstr(name,"192.168."==name))return(LOCAL_NET);
return(PUBLIC_NET);
Related
Basically I need to send data from Esp8266 to a server which is created using XAMPP on the laptop.
I have been using the following code on the ESP side
AT+CWJAP="dlink","password"
AT+CIPMUX=1
AT+CIPSTART=4,"TCP","192.168.0.105",80
AT+CIPSEND=4,6
123456 busy s...
AT+CIPCLOSE
My question is whether the IP address which i'm using is the correct IP for the server created using XAMPP? Do I need to send a GET request in order to send data? Do I need to make changes on the server side or just running the apache service is enough for my purpose?
The IP will be different in every network. I assume your network is set up with DHCP in which case the server might get different addresses every time.
There are mDNS libraries for ESP82666 that you can use to lookup the server by its local domain name (for example servername.local). Or you can configure the server to use a static IP.
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].
Is there a way to access a machine from outside the LAN without port forwarding?
I have two scenarios in my current setup port forwarding is complicating:
I have two FTP servers on the same router I want to access from outside
I want to Remote Control/Access files on Windows computers on the network
Right now, the first option is possible, but it needs reconfiguring the router, while other one seems impossible outside the LAN.
Is there something like [global IP address]/[machine name] or [global IP address]/[Local IP address]?
We need more information. Are these addresses IPv4 RFC 1918 addresses, publicly routed addresses, or IPv6?
If they are in the RFC1918 (10.x.x.x, 172.16.x.x, 192.168.x.x) address space then, simply no. Those addresses are not publicly routed and therefore must be translated to a non-RFC 1918 address.
Otherwise, yes, you can.
If your servers should be available to the public - the answer will be "no".
If you plan to give a limited number of users (for example, only you) access to this servers then you have some options:
Use SSH tunnels with, for example, PuTTY and set up a Forwarding for each service you want to expose to your computer and access it over localhost:port.
localhost:21001 --> 192.168.1.3:21 (FTP1)
localhost:21002 --> 192.168.1.4:21 (FTP2)
Advantage: you can setup your "port-forwardings" at clinet-side
Disadvantage: you need a router or another computer running the SSH server
Use a VPN (for example, OpenVPN, PPTP, etc.) to get access to your LAN from outside. Then you can act like you are in your LAN.
Advantages:
easy to use if setup properly
you can use almost every protocol
Disadvantage: Need to setup VPN Service/Gateway
I have developed a program in an academic project. This program includes a client and a server portion and aims to allow two notebooks to exchange information in an adhoc network:
The program should establish an adhoc connection with another computer
The program should send a message to the other computer through the adhoc connection
I did the first step. I developed a program that uses Windows WLAN API to connect to an adhoc network. The problem is the second step. I want to use Sockets API to send the message. Therefore, I need the IP address of the other computer. How can I get the IP address of this computer in an adhoc network?
I think you should be able to enumerate all the network interfaces connected to your network and dump the addresses known for each adapter. Something like this:
var addresses = Dns.GetHostEntry((Dns.GetHostName()))
.AddressList
.Where(ip => ip.AddressFamily == AddressFamily.InterNetwork)
.Select(ip => ip.ToString())
.ToArray();
Also take a look at ManagedWifi
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