in previous question i try to get all valid ip addresses in a subnet , so i use for loop , but after i try it , i find that my code takes more that 2 minutes to find an all ip addresses in a sub net , and in some cases it's take more than 5 minutes!
My code is writing in C++ under Mac OS ;
but in windows , to do the same thing you only write net view/all command , and it print all ip addresses in a subnet in a moment !
and in MAC os you can use Bonjour service to do such job .
how these techniques work like this speed (Net view /all and Bonjour service ) ?
is there any way to do this job very fast like this ?
if not please tell me if is it there is APi to use Bonjour service directly into my code (C++) in mac os?
EDIT:
i found new idea
i found on apple develop some api called Bonjour API , my be it's help ,but how i can use it i c++ , because i know that mac use opbjectiv-c .
bonjour
net view /all is working on Windows networking level, not on IP level. It will only list machines with Windows networking and name resolution enabled. If you have computers that are not running Windows (or samba) they won't be listed. The same with printers, routers etc.
With IPv4 the best way is to extract the list of IP addresses in the current subnet by examining the IP address and netmask of your computer. Then force an ARP lookup to be done of each IP address. The ARP lookup will always work if the unit is present on the network, even if it is completely locked down (no ports open, not answering to ping).
With IPv6 you are essentially out of luck. The number of available IP addresses in a single subnet (18 446 744 073 709 551 616) is so wast that an exhaustive search is impossible.
You should work asynchronously. You need a function that issues a communication request but returns immediately like IcmpSendEcho2. You will have to create an array of completion events for each call. Each event handle is passed to one IcmpSendEcho2 call.
After that you call WaitForMultipleObjects waiting for ALL events set.
Related
I want to create a C++ application that can be used (in part) to communicate between users on a local area network using UDP. Each instance of the application will have a thread dedicated to listening for other instances of the application and broadcasting its presence to other instances.
Is there a reliable way to perform this type of broadcast/listening on the LAN using pure C++ and POSIX system calls? I know there's no generally reliable way to find all IPs on a LAN, but I assume this is only because other devices are not willing to respond to pings.
Don't re-invent the wheel. There are two existing technologies, that, when combined, solve your problem in a standardized, well-designed, proven manner:
RFC6762 mDNS (Multicast DNS) is a protocol that works almost exactly like DNS, except it works using IP multicast. Instead of sending your DNS request to a unicast address, you send your DNS request to a multicast group, and any member of that group can answer your request (so you may get multiple answers).
RFC6763 DNS-SD (DNS-based Service Discovery) is a way to encode Services as DNS entries, which allows you then to retrieve Services from DNS using specially encoded hostnames. (For example, looking up the hostname _ipp._tcp.example.com would return a list of all printers that support the Internet Printing Protocol over TCP within the domain example.com)
So, we have one protocol that allows us to ask DNS about Services, and we have one protocol that allows us to ask a group of hosts to answer DNS queries … when we put the two together, we get a way of asking hosts for services! The combination of those two protocols is sometimes called Zeroconf networking, and is already implemented in macOS, iOS, tvOS, and watchOS (where it is called Bonjour), Android, most Unices (via Avahi, a portable implementation of those two protocols), and many home devices such as TVs. E.g. Spotify Connect, ChromeCast, Philips Hue and many others are also based on it. It's how iTunes devices find each other on the local network, for example.
Unfortunately, support in Windows is still limited, at the moment it seems to only exist for Windows 10 apps implemented in ECMAScript. (However, nothing stops you from shipping your own implementation with your app, and AFAIK, both Avahi and Apple's mDNSResponder work on Windows.)
So, what you would basically do is to send an mDNS query to the mDNS multicast group and ask for _myprotocol._udp.local. Then, assuming that your application registers itself with the OS's mDNS service (i.e. Bonjour on macOS, Avahi on Unices, …), you would get back a list of all hosts on the local network that support your protocol.
I need to write a program (preferably C/C++) that identifies running processes that connect to the internet, together with the domain name/URL they are trying to access.
( in case the process accesses a domain name, e.g. google.com, I need to be able to identify that domain name, not the resolved IP).
The program needs to run on Windows XP, Vista, 7.
From what I have studied, winpcap cannot identify the process.
I have searched stackoverflow on similar topics, but no satisfactory answer found...
Google for tools like tcpdump , tcptrace , tcpsplit , libpCap , wireShark. And you will be able to look at their source code about how to capture on going TCP/IP flows and analyse them
You can use Detours to hook the DNS, this is a project example: CodeProject and heres the Detours Page
I need to write a win32 c/c++ application which will be able to determine whether the PC it's running on is connected to one of 2 networks. The first network is the company LAN (which has no internet connection) and the second network is a standalone switch with a single PC connected to it (the PC that the program is running on).
I'm pretty new to network programming but so far I have tried testing to see if a network drive which is held on our LAN can be mapped. This works fine if the PC is connected to the LAN, the drive mapping succeeds so so LAN detection is successful. However, if the PC is connected to the switch, this results in a VERY long timeout which is not a suitable as it will delay the program so much as to make it unusable.
Does anyone have any alternative suggestions?
I'm using c/c++ in VS 6.0
[Update]
Whilst trying a few different ideas and looking at some of the suggestions below I thought I should update with some additional information as many (if not all) of the suggestions I don't think will work.
(1) The aforementioned LAN has no external connections at all, it is completely isolated so no resolving of external DNS or pinging websites is possible.
(2) Hostname, MAC address, IP, Default Gateway, Subnet etc etc (basically everything you see in ipconfig -all) are all manually configured (not dynamic from the router) so checking any of these settings will return the same whether connected to the LAN or the switch.
(3) Due to point (2), any attempts to communicate with the switch seem to be unsuccessful, in fact almost all networking commands (ping, arp etc) seem to fail - I think due to the machine trying to connect to the LAN when it isn't there :-(
One thing I have found which works is pinging the default gateway IP which times out when connected to the switch. This is sort of ok as I can reduce the timeout of ping so it doesn't just hang for ages but it feels like a bit of a hack and I would certainly appreciate any better solutions.
Thanks
As far as TCP/IP is concerned there is no such thing as a LAN on WAN. There are a set of non-internet routable addresses like 192.168.x.x and 10.x.x.x but these are sometimes used by ISP short of IP addresses.
You best bet is to use Asynchronous APIs when making TCP/IP connections. WIN32 defines a whole buch of OVERLAPPED APIs for this purpose. This will prevent your application from grinding to a halt while waiting for a remote connection.
Alternatively put the socket stuff into another thread and then only notify the UI when the operation is done.
I would first try to differentiate between the two using information available locally--that is, from your computer. Does the output of ipconfig /all differ depending on which network you're connected to? If so, exploit that difference if you can.
Is it possible to get the MAC address of the standalone switch? Of the switch that controls the company LAN? That would be a sure way to tell. Unless somebody cloned the MAC address.
If you try using the existence or non-existence of some network service to determine which network you're connected to, you can never be sure. For example, if you failed to map that network drive, all you know is that the network drive isn't available. You can't say for certain that you're not connected to the company LAN. Same is true if you use ping. Lack of response from a particular machine means only that the machine didn't respond.
Various things you can look at for differentiation:
DNS domain name (GetComputerNameEx)
MAC address of gateway (ping it, then GetIpNetTable)
Routing table(do you have a gateway and default route on the company LAN)
WNet discovered network resources (WNetOpenEnum, WNetEnumResource)
Ability to resolve external hostnames (try a 5-10 names like www.google.com, www.microsoft.com and so on, if one resolves you should have internet)
You'll have to decide how many indicators are "enough" to decide you're on one or the other LAN though if tests fail. Then keep retrying until you have a definite result.
http://msdn.microsoft.com/en-us/library/aa366071%28v=VS.85%29.aspx has a lot of network related functions that you can experiment with to create further indicators.
I'm fiddling with the sockets ioctl's to get the current interfaces setup and I can already get the IP, interface name, netmask and check if the interface is up or down, (I just do IOCTl to SIOCGIFCONF, SIOCGIFNETMASK and SIOCGIFFLAGS).
I am looking for a way to tell if my current IP address was obtained through dhcp or if it was static.
I can check /etc/network/interfaces for everything I want, but I'm looking for a way to do it programmaticly (does this word exist?).
Does anyone have any insight into this?
One more thing, I'm working on Linux (for now).
Cheers
With the wide variety of DHCP clients on Linux -- pump, dhcpcd, dhclient, udhcpc, and quite possibly others that I do not know of -- this isn't possible in a general sense.
However, if you are targeting a specific distribution -- say, "default install of Ubuntu" -- then you can investigate solutions such as Stefan's. Note that all four of the DHCP clients listed here can be installed on Ubuntu and can replace the default DHCP client, dhclient.
If you're running Ubuntu, the leases are stored in /var/lib/dhcp3/dhclient-[interface_name].lease, maybe that's a start.
I don't think its possible to tell via a kernel interface (ioctl) if an IP address was allocated via DHCP as in most distributions DHCP is a userland app that just configures the kernel with data provided by a remote source as if the user had done it manually. In fact, if you look at the ISC dhclient it just passes the data received from the DHCP server to simple shell scripts that do ifconfig, route and various other commands that you could type as a user.
So you'll probably have to look at methods that are specific to your DHCP client and distribution as suggested by Stefan.
i have known that winpcap library enabled a person to obtain advanced information about installed devices...
given all the networking devices found in the computer, how will i know which one of this has an internet connection?!
thanks:)
You typically don't care about this. Normally you just ask the network stack to make a connection, and don't worry about details.
However, each "device" will have its own IP address. You can request the network stack to use this IP address when making a connection.
Now, to figure which devices have an intenet connection, iterate over all of them, obtain their IP address, and try to create a connection from that originating IP to a destination IP on the Internet. Typically you already know such a destination IP, e.g. your companies webserver.
GetAdaptersInfo() will give you a list of all network adapters installed in a form that you can then use in GetIfEntry(). This latter function will tell you the operational status of an adapter, so you can at least tell if the adapter is plugged into a live hub/switch/router.
If you are particularly interested in IP connectivity, you could look to see if a default gateway is configured for that interface. Don't forget you might have to support IPv6 as well as IP4 if you try this.
Correlating the network adapters found by GetAdaptersInfo() with those found by pcap_findalldevs() is left as an exercise for the reader. I don't remember the details but it was fairly obvious.