Questions tagged [ipv4]

For questions about Internet Protocol version 4 (IPv4); as specified in RFC791.

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2answers
162 views

A question about firewall usage

I have a project that includes a firewall and two routers. I have created two subnetworks with VLSM for both routers and I have a cable that represents a serial connection between them. The firewall ...
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1answer
168 views

Determine the minimum address range that contains some given IPs

I recently started to learn how IPv4 works. I know how to divide a given address range in smaller ones and set up a network in that way (at least in Netsim K). But I wanted to do a bit of something ...
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2answers
448 views

'Copying' UDP Broadcast to Specific IP Address?

I'm very inexperienced in networking, so please pardon any idiocy. We are mechanical engineers trying to connect weird hardware that talks on Ethernet. We have a device A that can only send UDP ...
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1answer
529 views

How to design a physical topology? [closed]

I need to design a network. I'm a newbie and going step-by-step. Let me briefly explain my little "project" to you: I'm designing a network to a company. This company has two offices at two distant ...
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2answers
4k views

How can a router change the IP address like that?

I would like to ask something. Probably, that was a simple thing but I'm new at network business so thanks for your kindness. In the topology image given below, the router "Router1" has an ...
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1answer
189 views

classless network [closed]

I'm having trouble figuring setup for my network, have done quite some reading and testing already, yet still, some solutions remain unclear to me and I hope to find an answer for these here. What I ...
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2answers
409 views

How does CIDR help in routing

Classless Inter Domain Routing (CIDR) is a method to allocate IP addresses and route IP packets. I understand how it saves IP address space but I dont understand how it helps the routing process , ...
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3answers
3k views

Finding all used IP addresses within a LAN without assigning an IP address to your NIC

I've been wondering if there's a possibility to find the IP addresses of all the nodes connected to a particular LAN without assigning your NIC an IP address.Taking under consideration that some nodes ...
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1answer
123 views

IP Conflict in the Network

I am not a Network administrator, but i am having a IP Conflict in one of the system that uses Static IP (A Application Server), other systems are given Dynamic IP addresses. I just want to know ...
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1answer
3k views

What are the differences between classful and classless subnetting? [closed]

ip: 10.5.2.1 subnetmask: 255.255.255.240 {10.5.2.1/28} what is correct maximum subnetworks ???? What are the differences between classful and CIDR subnetting????
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1answer
440 views

What is the difference between Unicast RPF and Reverse Path Forwarding?

What is the difference between Unicast RPF and Reverse Path Forwarding? They both verify the source address of each packet before forwarding it to the destination. Is Reverse Path Forwarding used ...
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1answer
64 views

Port restrictions and MACs [closed]

I have a question regarding connections within a university setting. In my room I have two network points. One for my pc and one for my voip phone. Each network port is restricted to one mac address, ...
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1answer
1k views

how to create a file in Cisco IOS

I want to make a file in Cisco flash to use as static mapping file for the DHCP , how can i do this? is there any command to create a text file in IOS
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1answer
709 views

Update IP Geolocation for new public IPs [closed]

We have been recently assigned new public IPs by ARIN but we have been having trouble with IP Geolocation. Some services block our IPs saying they are outside the US, others locate us in the ...
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1answer
187 views

Why does my router get kicked off network? [closed]

My network has a server that does DHCP, and I have a switch that connects multiple computers. Currently I have a wireless backup solution that works subpar and I would like to get ADSL up and running. ...
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1answer
544 views

Multiple DHCP Offers - Which is selected? [closed]

I have created a testing scenario in VMWare for a man in the middle attack using DHCP spoofing. It's for a college project. Windows 8 machine bridged to host adapter Kali linux bridged to host ...
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2answers
520 views

Strange IP packet payload corruption [closed]

I'm working on developing a transport protocol layered directly atop IP and while performing an experiment to see how routers on the internet would react to an undefined protocol I've observed some ...
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2answers
171 views

EIGRP protocol not connecting networks together

I have used the EIGRP protocol to connect the relevant networks but it will refuse to acknowledge the presence of the other network I shall write the map out with the relevant addresses: Main Router -...
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2answers
5k views

Router unable to assign IP addresses to ports

Alright, so I have a 2811 router in Packet Tracer 6.1, I equipped it with what I thought were FastEthernet ports, even though it shows up when I'm cabling them as 'FastEthernetx/x'. **(The equipment ...
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1answer
3k views

Under what circumstances are multiple loopback (127/8) addresses useful?

I made an app in java where a client sends ip-packets to a server via the looback-address 127.0.0.1. A really simple app just to test how things work. At first I thought If I created several client-...
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4answers
1k views

Network Address used for hosts?

I was always taught that a network address (eg. 192.168.1.0) cannot be the IP address of a host? Is there a reason for this? After all it isn't used anywhere else like a broadcast address.
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0answers
132 views

Is it possible to link two VPS Cloud servers together? [closed]

Is it possible to link two VPS Cloud Servers together to be used as one. If I have two vps cloud servers and each have 80GB of space and 1TB bandwidth can they be linked together as one to have 160GB ...
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2answers
15k views

Subnetting Question [closed]

Consider a router that interconnects three subnets: Subnet1, Subnet2, and Subnet3. Suppose all of the interfaces in each of these three subnets are required to have the prefix 223.1.17/24. Also ...
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1answer
140 views

Host Not Accessible [closed]

A strange thing happened recently. I have a few servers that have statics IP's and I can not longer access the servers. I cannot ping or trace them. However, I can go to their web portals. Each server ...
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2answers
2k views

Forcing an ARP request [closed]

I'm writing a program that detects ARP poisoning. What I want to do is somehow clear my routers ARP cache, so that it can force send an ARP request, so then I can check the source address of the ...
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2answers
1k views

Mikrotik CloudCore1036 static DHCP configuration using multiple NIC - LAN and WLAN [closed]

My question is it possible to configure CC1036 like a DHCP server which would be able to: gives to specified host (for example Local Station 5) same IPv4 address based on his MAC LAN and MAC WLAN ...
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2answers
613 views

splitting an already in use subnet

Note: the below examples are probably not realistic but work with the question. Say I am attempting to plan for the future and I allocate a 10.1.0.0/16 for a certain floor of a building but do not ...
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2answers
889 views

Arping for local broadcast address

Given the local IP-network 10.173.128.0/24 I am looking at a wireshark and there is an ARP for 10.173.128.255. Why would a network client ever ARP for a broadcast address? Does this indicate a ...
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1answer
3k views

Can access website with URL but not IP [closed]

The following command ping www.yesshou.com gives the IP address of this website as 118.126.13.10 However, while I can access this website using the URL, I cannot access it using the IP address ...
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5answers
20k views

Is a 192.169.0.0/16 a private address range?

I know that 192.168.0.0/16 are adresses reserved for private networks. What about 192.169.0.0/16 addresses and other.. in 192.0.0.0/8. Are they routable in the "Internet" or are they also private?
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2answers
290 views

IP packet fragmentation - not all fragments recieved

What happens on a recieving device, when not all the fregments are recived? The last fragment has the "more fragment" flag set to 1, meaning there should be another fragment after. But somewhere ...
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1answer
2k views

How packets know which device on another lan to go to [closed]

If I know the public IP address of a network, I can talk to the router for that network.. But how would I specify to the router which device in the network I want to start talking to? What I'm asking ...
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2answers
2k views

What's the difference between a local-link address and a local-link route?

AFAIK Local link addresses are addresses that can only talk to devices within its own subnet. Routers will not forward packets that come from local link addresses. Local link addresses are defined in ...
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1answer
4k views

How to add Options in IPv4 Header

I am working on a project in which I need to add some options in the IPv4 header field. I am following this draft for the implementation. I have a doubt! As the above mentioned draft says, I need to ...
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6answers
1k views

Is there any way to know if two nodes are connected to the same switch or not?

If I have two nodes/computers connected to each other on the same range of IPs. Say: Node A: 192.168.0.1/30 Node B: 192.168.0.2/30 How to know (from Node A) if B is connected directly to it (via the ...
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4answers
20k views

How to divide an IPv4 network into subnets of different sizes as efficiently as possible? [closed]

I need to divide a network 172.16.0.0/12 into 3 different subnets for different purposes. One of them needs 6 host addresses, another 85 host addresses and the last 100 host addresses. It should be ...
5
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1answer
681 views

Who assigns IP s to the ISP s?

How a particular ISP get it's IP ? Is there any centralized authority to distribute IP s ?
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2answers
1k views

Man In The Middle on IPv6, are IPv4 packets affected?

If I successfully Man in the Middle attack an IPv6 Address of my victim can I also sniff its IPv4 packets? Attacks like Neighbor Advertisement Spoofing or Last Hop Router?
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1answer
300 views

Broadcast to subnet

Will a broadcast on a supernet broadcast address reach all the subnets? For example if I sent a broadcast to the address 10.172.255.255, would it affect the clients in the subnet 10.172.2.0/24?
2
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1answer
157 views

When using AS prepending in a multi-homed BGP environment, how fast is reconvergence of inbound traffic when the primary router goes down?

When using AS prepending in a multi-homed BGP environment (primary/secondary routers, secondary prepends one more ASN), how fast is reconvergence of inbound traffic when the primary router goes down? ...
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1answer
394 views

Rediscover method of calculation Subnet [duplicate]

I am preparing for my CCENT exam and about 3-4 month ago, I had found a method of calculating subnet. Unfortunately I did not bookmark the site and i forgot how to do it. All I remember is how you ...
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6answers
5k views

Raw IP communication?

I'm studying the difference between the protocols IP and TCP. IP is said to provide an unreliable datagram service whereas TCP provides a reliable bytestream service. Further, TCP works on top of IP. ...
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2answers
1k views

Why is this a network if all host bits are zeros?

let's say that we have a router with address: 172.31.219.33/27 from this I can tell several things: Subnet mask: 255.255.255.224 Broadcast address (here I am not sure if last digit should 64 or 65 - ...
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3answers
2k views

Is it possible to brute force search/guess symmetric NAT port prediction for hole punching?

Say we have two clients A and B that wish to connect to each other, both behind symmetric NAT's NA and NB respectively. Also there is a rendezvous server S that exists to assist clients A and B with ...
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5answers
655 views

Why is the IP layer aware of higher layers in the network stack?

In the IP packet header there is an 8-bit Protocol field (at offset 9) that holds the "next level protocol", with assigned numbers given in RFC 790. For example, TCP is 6. My question is, why is the ...
6
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2answers
15k views

Local pref VS prepend AS-path for two eBGP router

I have two routers, AS50 and AS100, both are under my control. Since they are using different ASN, they should be eBGP routers. These two routers are connected by internet VPN and lease line, which ...
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4answers
4k views

Ipv4 routing - 2 host of diferents nets ping each other in the same Hub

Look this scenario. Host 1: Ip:192.168.0.1 mask:255.255.255.0 gateway: not defined Host 2: Ip:192.168.1.1 mask:255.255.255.0 gateway: not defined Is it possible to ping from host 1 to host 2? ...
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2answers
162 views

Purpose of network address in IPv4? [duplicate]

While broadcast address in IPv4 is used to send traffic to all the hosts in the network, then what is the purpose of network address in IPv4 network?
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1answer
486 views

Multicast over Unicast IPv4 Routing

I have a little question and I did not find any direct answer on the WWW. So maybe someone else in this forum has the answer. I have two Cisco 2960X switches running in a stack with the sdm prefer ...
3
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2answers
4k views

subnetting, nested subnetting, VLSM & broadcast addresses

A teacher told us about VLSM and "nested subnetting": you should NOT use all-1 / all-0 subnets the same public network you got, can be split up in subnetworks of different size / having different ...

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