I'm trying to setup a connection b/w GNS3 Router and Local PC. Following are the steps done so far in GNS3:-
1. setup a router interface, e0/0/ = 192.168.1.1 255.255.255.0
2. created a cloud loopback adapter, interface, and assigned IP = 192.168.1.5 255.255.255.0
(Note: loopback adapter has been created as Mictosoft KM-Test loopback on my PC. and same interface has been added to cloud in GNS3 which is then connected to Router interface, e0/0)
When I tried ping from my PC to GNS3 R, arp entries get created in Router (running on GNS3 topology). See below:
RTR#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 192.168.1.1 - aabb.cc00.0200 ARPA Ethernet0/0
Internet 192.168.1.5 134 0200.4c4f.4f50 ARPA Ethernet0/0
But ICMP isn't successful on Router (See below) :-
RTR#ping 192.168.1.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Can anyone help here pls ??
Try setting the IP address of the KM-Test adapter to an address outside your home network. Such as 10.0.0.1/24. Attach your cloud to the network adapter and then create persistent static routes by opening a command prompt as administrator and entering the command.
route -p add [Destination] mask [Subnet Mask] [Gateway(KM-Test)]
Note that any additional network you create within GNS3 will need a static route so that windows knows to send your packets through the KM-Test rather than your home network gateway.
Related
Trying to connect to a react app that is running inside a Virtualbox wit Ubuntu 18.04.
Did the network config on virtualbox by adding a second network configured via NAT and added all my forwarded ports.
Ports forwarded:
Server ports listening:
Result when trying to connect to port:
My problem is that all the other ports that I am forwarding work perfectly except for 3000 or 3001, which are both react apps.
What am I doing wrong?
You should specify Host IP and Guest IP in port forwarding.
To define Guest IP you need to call ifconfig command via console and find inet addr. In my case it equals to 10.0.2.15.
Your Host IP is 192.168.0.6 based on the screenshot above.
Please Clarify my doubt in ARP. In the below Topology,.
Looking for better understanding, how ARP works when Hosts are connected between default Gateways .
Host A(10.10.10.1)-----Switch-----(10.10.10.2)Router(20.20.20.2)--------HostB
When a Host want to communicate to Host B , does hostA send an ARP request for Destination IP (20.20.20.1) or to Default Gateway (10.10.10.2) .
If it send ARP for HOST B mean, Host A identifies Host B is in different network, it will send the Packet only to the Configured Default Gateway , so will it request for Default Gateway Mac address
Host B mac will not be learnt by Host A by any cost, So does Host A will generate ARP request for each time?
Since a MAC address is only useful for a layer-2 domain which is bounded by a layer-3 device (router), a host will not ARP for a MAC address on a different subnet unless it has a misconfigured mask.
The host will ARP for the address of its configured gateway so that it can send the frame to the gateway, and the gateway will remove the layer-2 frame and try to forward the layer-3 packet to the port toward the end host. The router will then encapsulate the layer-3 packet with a new layer-2 frame (possibly using ARP if the nest hop isn't in its ARP cache) for the next link.
I have been trying to setup a cisco gateway router that has a Mail server behind it. The challenge has been that the static nat entries are no effective or perhaps do not work. Has anyone done this in areal life environment? testing for open ports shows that all the static NAT ports are closed .Please share
Try this:
ip nat inside source static tcp LAN_MAIL_IP_ADDRESS 25 MAIL_PUBLIC_IP_ADDRESS 25 extendable
!
interface FastEthernet0/1
description "TO INTERNET"
ip nat outside
!
interface FastEthernet0/0
description "TO LAN"
ip nat inside
I Actually found out that the problem was the gateway on the mail server that was still pointing to the old ISP instead of the router connecting to the new ISP.
Please if you can help me about my problem. On one side I have server with IP 172.27.13.2 connected to the WAN interface of router 172.27.13.1 ...Then on wireless LAN of my router 192.168.1.1 I have connected a few clients. Now I will write code in C where client are requesting some UDP streams from server, then server broadcasts streams to clients, and if some packets get lost clients must send NACK to server. My questions is:
Because server and clients are on different subnets how can I broadcast from server?
And how the client can send request and NACKs to server because they are in different subnets?
Are these problems can be solved by router configurations or in C code?
Thank you for helping
You cannot broadcast to different subnets. Routers do not usually forward broadcast packets to different subnets, unless you have a very special router that can be configured properly (e.g. Cisco ...). You could however use multicast for such a task. Here's a C example
Also check this: UDP broadcast packets across subnets
NOTE: some includes in the c example are missing, but they are easy to find
As both server & users are in different subnets .As router donot forward broadcast .But we have solution by modifying the router configuration .
If you have cisco router & users are connected on cisco switch ,you can use ip helper address command on switch on vlan .You can allow udp packet on router ACL
My question is, how to connect to socket on romote mechine?
I can only connect sockets on same network..
I wrote a simple code (in c), that simulate a server (open socket and listen for client). in Mac.
I'm trying to connect this socket as a client from iPhone (with simple objectiv-c code).
If my internet on both, server and client, is on the same network (WiFi) and in client I trying to connect to 192.168.1.x, it's working.
But when, in client, I'm trying to connect via external IP (with the same port) connection is failed.
I never did this bofore. Maybe I miss somthing.. I've tried to turn my FireWall off. It did not help.
Thanks.
Edit: If it's not clear.. my Mac is connected by router.
In a setting like this, the "external IP" would typically be the IP of the router. In all likelihood you'll need to configure the router to forward the relevant port to the internal IP address.
It could also be the case that for the port forwarding to work, the request has to come in on the external (WAN) interface. This depends on how the router is configured. If that's the case, you'll need to make sure that you're accessing the external IP via the cellular network and not the Wi-Fi connection on your iPhone.
If you're connecting to your server via a local IP address (i.e., you're connecting to another machine on the same local router via a delegated DHCP address), then your issue is on the network, not the IP-stack of the local machine.
You'll need to look into your router settings ... many routers will block a number of services, especially those on custom ports, in order to prevent malicious attacks from sources external to the local network.