I have written a network client for iOS which uses the SCNetworkReachabilityCreateWithName() function to initiate monitoring of the availability of the remote hosts. This works beautifully if the remote hosts have only IPv4 addresses or only IPv6 addresses.
A problem arises when the client is on an IPv4 only network and is monitoring a host which has both an IPv4 address and an IPv6 address. The client will monitor the IPv6 address of the remote host and indicate that the host is unavailable even though the IPv4 address is reachable.
I've searched and have been unable to find a way to instruct SCNetworkReachability to default to monitoring the IPv4 address if an IPv6 network is unavailable.
I can work around this by programmatically determining the public IP addresses of the device, manually resolving the hostname, and using the IPv4 address if a non-link local IPv6 address exists, however I'm hoping that someone has a simpler solution.
Since the functions are the same for both iOS and OS X, this problem would affect OS X clients as well.
My specific implementation is the .m and .h files for my BKNetworkReachability class:
https://github.com/bindle/BindleKit/tree/master/BindleKit/controllers
Related
Through tcpdump in dhcp-server, it shows the server can receive the DHCPDISCOVER package and send the DHCPOFFER package, but can not receive the DHCPREQUEST package from the dhcp-client, so the client can not get IP address and always in send DHCPDISCOVER package.
But the dhcp-server which runs in VMWARE's instance can send DHCPACK to client and the same client will get the IP success. The dhcp-server using the same configure as in Openstack's instance.
And, if I configure the static IP address in the client instance, it will ping the dhcp-server's IP successful.
One more thing, the server and client are in the same vlan.
Is there any limit rule in Openstack's instance? How can I resolve this problem, THX.
The essential reason is that the traffic of port is limited by the security groups in openstack.
By default, all security groups contain a series of basic (sanity) and anti-spoofing rules that perform the following actions:
Deny egress DHCP and DHCPv6 responses to prevent instances from acting as DHCP(v6) servers.
Resolution:
disable security groups (no recommend)
set dhcp-relay to the dhcp server in router (recommend)
security groups limited the traffic by hypervisor's iptables which will drop the packets which's src port is 67 and dst port is 68.
DHCPOFFER packets will send to router by src and dst port 67, and it will works to all vlans.
For DHCP relay and DHCP proxy, packets sent to the DHCP server from the router have both the source and destination UDP ports set to 67. The DHCP server responds using the same ports.
Maybe there are some methods but I can't find out until now ?
I want to make an http request via the fetch() method in React Native, and I need the IP address of the machine I'm sending the request to. I have access to the machine, and googled "what's my IP" on it. It said my public IP was 162.250.198.98, but when I googled it on another computer nearby, it gave the same address. Is this the right IP to use in a fetch request like this? If not, how do I find the right one to use?
If you have multiple machines connected to the internet via a NAT-enabled router, they will all share the same public IP address. You need to forward a specific port to the machine you want to connect to in the router's configuration e.g. to send your request on port 5000, add a rule to the router to forward port 5000 to your desired machine, then send the request to 162.250.198.98:5000
For your application to work you need a "server" with a public ip address. Later you assign a domain name to that server/ip address ex. api.domain.com
Since you don't have a server and you are using your computer to test your development, you can do this 2 options:
Use your computer IP address usually 192.168.x.x , 10.x.x.x or 172.16.x.x This will allow you to test it if your phone is connected wireless to the same network.
Since you are behind a NAT you can do a port forward to send the traffic to X port to your desired host(ip/port) behind the nat. Usually we create API's that run on port 80 or 443 do a port forward in your router to pass the traffic from this port to your computer ip/port.
I don't have a ton of experience with routers or port forwarding, but I do have a new Raspberry Pi and I wanted to see if I could set up a simple Hello World page just for educational purposes. I have quite a bit set up with apache2 already installed and the web page works great on my local area network, however I can't connect to it using my LTE from my phone, telling me this thing does not connect to the internet.
I am currently using Rasbian under all the default settings from the pi.
My router is an all in one modem and router, from xfinity. After sifting through countless sites trying to solve this issue, the following 2 were the closest thing to my particular issue. My reputation is not high enough to put more than 2 links, so I will put the most important ones..
So to the best of my knowledge this is the way to do it ...
1) Set the web server up to work locally
2) Then go into the router with the IPv4 or IPv6 (shouldn't matter which) and forward all Port 80 traffic to, say, Port 8080 where my PI 'should' be listening, then send back my web page down through Port 80 to the client calling the web page.
Under 10.0.0.1 I find this...
Then I go to 'Advanced'
I have tried from Start port 80 to End port 8080, which my 2 PI files I edited to listen for that port.
Those files are under
sudo nano /ect/apache2/sites-enabled-000-default.conf
and
sudo nano /ect/apache2/ports.conf
I changed
Listen 80
to
Listen 8080
and all other combinations alongside changing my router Start and End ports... none of which worked so I am lead to believe there is either a knowledge gap or I am doing something terribly wrong.
I just want to put a simply Raspberry pi web server online from my Local connection at home using a Comcast xfinity router. If anyone has any experience doing, I would seriously appreciate it, I've spent far too many hours trying to walk through this alone, so now I am reaching out to the faithful stackoverflow community.
It sounds like you are almost there.
For you to be able to access your raspberry pi server from the internet, you need to find your external ip address. Your router has one external ip address that you can reach from the internet. While on your wifi, search google for "what is my ip" Google may display it as the top result, or you might have to click into a site like ipchicken. Write this IP address down.
Next, setup your router to forward all port 80 (default http port). Try setting Apache to listen on port 80, and have your router set with start port and end port to be port 80 (this makes it so you don't have to put :port-number in the address, i.e. you will do http://your-ip-address rather than http://your-ip-address:8080). The start port is the port on the external network, the end is the port that your Apache server is running on the raspi.
It looks like your raspi has the ip address of 10.0.0.17 on your local network based on your screen shot. If it doesn't, change the IP address in the port forwarding section of the router configuration to be the IP address of your pi. You can figure out what the assigned IP address of your pi is through the router interface, or by typing ifconfig -a and looking for the ip address of the adapter that you're using to connect to the network. Your router may have the ability to assign a static ip address to your raspberry pi while it's connected to your network. It would say something like DHCP reservation. You'd need to find the MAC address of your pi. You can do that with ifconfig -a as well. Then configure your modem to always assign your pi the same ip address that you've configured in the port forwarding.
Now that everything is setup, switch to your cellular connection and then try to go to the ipaddress that Google gave you.
type your-ip in browser address bar -> port 80 request to your modem's IP -> you've set external port 80 requests to be forwarded to port 80 on your internal network for the device 10.0.0.17 -> your raspberry pi will serve the HTML
Note: The external ip address of your modem is most likely not static unless you specifically pay for a static address. This address usually will stay the same for at least a day though, so if you're just testing, it's not a big problem. In the future, if you want to ensure that you'll be able to reach your pi, look into dynamic dns.
I have installed Ubuntu on Windows 8 using Hyper V. Having also installed Apache 2 I had the notion that I was going to use this as a web dev environment. I set up an external switch so that my ubuntu installation could access the internet. So far everything was progressing swimmingly. The problem I am encountering is that I have no idea how to access the web server from my machine. I can get the IP address that ubuntu picks up and type that into my browser whereupon I am informed "It works!". That's all good but I move around among several networks and I should not have to look up the IP address every time, and that can't facilitate having multiple sites installed. I just want to be able to enter something like
"http://mytestserver/"
into my browser to access it.
Any pointers on how to set this up properly would be much appreciated.
I have always had the most success with Bridged networking in VM Guests and would definitley recommend you go with that option. What you then could do and what I have done is to assign a static IP for the server and assign the hostname as below. You will have to know what IP addressing is available or you can use 192.168.1.x if your inside your network.
The easiest way would be to assign a static IP in /etc/network/interfaces replacing the 0.0.0.0 with the correct entries for your network
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 0.0.0.0.0
netmask 0.0.0.0.0
gateway 0.0.0.0.0
broadcast 0.0.0.0.0
dns-nameservers 0.0.0.0.0 0.0.0.0.0
and then edit your /etc/hosts file and add that static IP and add the Hostname mytestserver. You will already have the localhost entry and possibly others. Just make sure you assign the Static IP address you assigned in interfaces to mytestserver. You may also have to make this same entry in your machines hosts file simply because it will not have a DNS record.
127.0.0.1 localhost
0.0.0.0 mytestserver
I have two real machines.
One is responsible for NAT and IP redirect called NC2 and another is responsible for eucalyptus KVM established 3 virtual machine.
No doubt, the OS of machine which is responsible for eucalyptus is Linux.
The guest OS of virtual machines are Windows XP.
Each virtual machine is a web server which runs Tomcat
NC2 gives an private IP 192.168.0.3 to Linux server.
Linux server gives 3 IPs which are private class B to virtual machines.
For example, one of guest OS gained IP 172.16.1.5
Now I use NC2 to redirect a physical IP x.x.x.x to 172.16.1.5
Here is my problem:
I can use other PC ,outer IP, connect to the website which is established on 172.16.1.5 with IP x.x.x.x, but I can't use machine with IP 172.16.1.5 to connect to it's own website.
I turned off the firewall on 172.16.1.5, and it's able to connect to internet such as yahoo or amazon. But it just can't use x.x.x.x to connect to it's own website.
I tested other guest OS which are gained 172.16.x.x also not able to connect to x.x.x.x.
How can I do to make guest OS connect it's redirected physical address?
It look likes this is caused by a NAT issue called 'hairpin'. Here is the explanation:
Let machine A on a LAN have a private IP address 192.168.0.10.
Let NAT N translate A's private IP to public 77.33.45.67 for the WAN.
Some 'early/old' NATs take for granted that the translated address in only going to be used from the WAN. Therefore, they don't forward packets on the LAN having ip address = 77.33.45.67 and only let in and forward those with this ip address when they come from the WAN.
This problem is solved in more recent NATs which detect these situations and forward packets properly. This problem is sometime encountered in P2P systems.
If you are lucky, your NAT be may be reconfigured to enable usage of translated address on the LAN. If not, then you need a new NAT.