Questions tagged [ipv4]
For questions about Internet Protocol version 4 (IPv4); as specified in RFC791.
726
questions
0
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0answers
10 views
Are network IP addresses ever used as source or destination IPs? [duplicate]
The first IP address of an IP subnet is the network address, which stands for the whole network, while the last address is the broadcast address.
As far as I understand, we never really send packets ...
0
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0answers
15 views
TCP connection closes instantly (without timeout) when I change my IP address through the windows network and sharing center [closed]
I have tcp connection to some tcp server on internet. Tcp client is a simple application that I have created which works on my computer. The problem is that when I change my ip address through the ...
0
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0answers
13 views
IPv4 header length maximum size [closed]
The minimum header length is 20 bytes but in the datagram the IHL is only assigned 4 bits. Why it is like that?
1
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1answer
34 views
IPv4 maximum datagram size
The IPv4 datagram consists of two parts:the header length and the payload. The maximum header size is 60 bytes and minimum is 20 bytes. The maximum size of the data can be 65515 bytes. So why the ...
-1
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0answers
17 views
Why does `curl <this machine's IP>` behave differently than `curl localhost`? [closed]
I have two Raspberry Pis on my network - let's call them Pi and Rho.
I'm trying to set up port forwarding via ssh tunnel between them, such that an application can connect to a port on Rho and get ...
0
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0answers
8 views
Cannot port forward traffic from public IP (WAN) to OpenVPN (remote) clients [closed]
I'm looking for some advice here or a nudge in the right direction, seeing as I've reached an apparent dead end.
I have a static IP for my business (200.78.xxx.xxx) and I set up an OpenVPN Server on ...
1
vote
1answer
127 views
Broadcasting to unknown Class C Network
I am trying to use python to broadcast to my local network, and I cannot find a way to get the subnet mask. I have been suggested to use the default Class C network subnet mask 255.255.255.0, and use ...
1
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2answers
43 views
Where are broadcast packages filtered out
When I have one network with a switch. Within that network I have 10 PC. Halve of them are configured within the 192.168.1.0/24 range and the other halve is configured at 192.168.2.0/24.
This means I ...
0
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1answer
36 views
Find Routes not containing these subnets [closed]
Let's say I have 1000 ranges and I would like to make routes that doesn't match these ranges, anyone has any particular tips or tools to share beside doing math ?
Example :
I have these ranges
13....
2
votes
1answer
53 views
Why Classful addressing is not in use if we can subnet them?
So,
Let's think that organization needs 5000 IP addresses. Giving 20 C Class IP addresses will cause of adding 20 entries for ISP router. That's problem. We could give Class B IP address, but that ...
0
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0answers
19 views
How to find minimum of hosts bits needed and assign equally to five subnets? [duplicate]
I have a 192.168.1.0/18 network block. How do I determine the minimum number of host bits to be borrowed and assigned equally to five subnets? How to calculate the number of users that can be ...
2
votes
2answers
49 views
The MSB of IPv4 flags
In IPv4 header, there is 3 bits field called "flags". The MSB of this field must be reset to zero (as many networking blogs say without telling why).
i want to know what will happen if I managed to ...
0
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2answers
57 views
Do NAT devices need to have private IP addresses?
If a NAT's job is to create mappings between internal ip/port pairs and external ip/port pairs with one Internet-routable IP address, does a NAT need a private IP address for itself? I think one ...
0
votes
2answers
55 views
Routing Table Settings To Access An Internal Network Through VPN
I have a remote computer behind a VPN (which I have no control of). The IT team of the remote factory wanted me to install Palo Alto Networks' Global Protect program to access the VPN, which is ...
0
votes
1answer
69 views
Can I run 2 separate ranges on the same physical network
My current set up is 1 router and 2 switches, the router being 192.168.10.1 with a connection to each switch then 8 and 10 devices on the 2 switches all 192.168.10.x
I have an NVR with 2 ports, 1 of ...
0
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2answers
58 views
When a packet is received, how does it know which internal machine to send it to?
I am familiar with ARP and routing, but I think I am failing to put two and two together here. On an IPv4 packet we have the source IP address, which allows any router to send the response back to the ...
2
votes
1answer
37 views
Is an IP broadcast always a layer 2 broadcast also
On my PC I see 255.255.255.255 in ARP with MAC FF:FF:FF:FF:FF:FF, so I'm assuming that in most cases the L3 broadcast is also encapsulated into an L2 broadcast frame, but is this standardized?
For a ...
0
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2answers
52 views
Why can some people use public ip address to access a server from an internal network with the client device within the internal network
As the title suggests. I find it mind breaking to think how network architecture can differ to allow/not allow using public IP address to access a server within internal network from within the ...
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0answers
26 views
How can I configure a Cisco router 4300 to allow internal server ip:80 to be accessed on public ip:4500
I have an internal web server on port 80. I need help commands maybe to configure port forwarding to access the server on my private network from a public IP
Current running config
interface ...
1
vote
2answers
324 views
MTU the most Confusing Networking term. Lot of questions
I have ton of questions and i feel this is most confusing term for me. The more i read the confusion deepens.
I am not able to connect dots. please help.
Do we need MTU adjustment with EoMPLS/dot1q ...
1
vote
1answer
38 views
IPv4 Subnetting for 1200 or more devices for WiFi
I am currently looking over my schools existing Subnets and their usage. Some seem to be sufficent, others not so much.
What is the best practice when you need to support 1200 or more devices on a ...
1
vote
2answers
65 views
Question about the destination IP inside an IPv4 packet
I'm reading about link and network layers for the first time and I'm trying to put the pieces together to understand how they work together. My question may not have to do with the link layer but I'm ...
0
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0answers
9 views
Given a subnet mask, how can I determine which addresses can be assigned to public network hosts? [duplicate]
For example, I'm given a subnet mask of 255.255.255.248 and need to determine from a list -
16.70.118.63
134.178.18.56
200.47.224.159
68.111.178.93
192.168.16.87
217.37.10.192
- which addresses can be ...
0
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0answers
13 views
Building simple network configuration [duplicate]
For the below network configuration I need to propose an IP addresses, netmask and anything else obvious that I am possibly forgetting.
The network is built of four Computers, Router and a Switch. I ...
17
votes
5answers
8k views
Usage of 192.168.xxx, 172.xxx and 10.xxx in private networks
I know that the organization that distributes IP addresses decided to assign 192.168.xxx, 172.xxx and 10.xxx to private networks. However, I thought that private networks have their own address space ...
1
vote
0answers
23 views
Is it possible to access 127.0.0.xxx in anyway [closed]
So I've been configuring my network at work. We've got a lot of devices from NAS servers to Dante AoIP devices.
While configuring some of my devices I managed to set the IP adress of one device to ...
5
votes
3answers
2k views
Does NAT violate end to end argument?
Does NAT violate end to end argument?
What does end to end argument means in this context?
2
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0answers
53 views
How is it possible to have a default gateway outside of the network range of any interface? [closed]
I always thought that the default gateways has to be on the same network as the server/client trying to connect to the internet. However today I rented a server from Hetzner and the server is able to ...
1
vote
2answers
42 views
How TCP connections between origin and node servers over a BGP Anycast gets established?
Server A and B have the same IP address with anycast. Server B connects to the origin server that is very close to server A and very far away from server B, since server A is closer, the response will ...
0
votes
1answer
46 views
Remotely Connecting an IPv6 Computer to a IPv6 Private Web Server
I have a private web server at my office, and I want to access that server remotely at my house via IPv6.
My office has both IPv4 and IPv6 enabled, but my home has only IPv6.
IPv4 works, but I have ...
0
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2answers
81 views
Loopback with / 32
When we dealing with bgp, osp. Why do we especially use loopback interfaces with / 32!?
Is there an advantage or something different from other subnets like 24.
0
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0answers
11 views
Why is the source / destination address ordering in IPv4 and IPv6 headers opposite of Ethernet source and destination MAC addresses? [duplicate]
Engineers always do things for a reason.
I've noticed that in Ethernet frames, the ordering is destination MAC address first, and then the source MAC address.
What's the reason for reversing the ...
0
votes
1answer
43 views
Setting the network address freely [duplicate]
I'm trying to understand IP Addressing, but there's something what's still not clear for me.
With mask
1111111.1111111.1111111.00000000 (/24)
Am I able to set network address "freely" like this?
...
1
vote
1answer
40 views
Next Header field in IPv6 vs Protocol field in IPv4, any difference?
So I am new to the IPv6 concept, and I seen that the Protocol field seems to be replaced with Next Header, and I have a question.
Question:
Is Next Header a complete replace of Protocol, or is they ...
1
vote
3answers
118 views
What is the intuition behind subnetting a base IP?
Take a look at this picture:
My professor usually gives a topology like this and gives me a base IP. Let's say the base IP given is: 223.1.0.0/24. We're then asked to construct the given topology by ...
2
votes
1answer
73 views
Confusion about IANA “Protocol Numbers” registery
In the IANA registery for "Protocol Numbers", there listed 2 IP protocol versions: IPv4 at #4 and IPv6 at #41. Their "protocol" column says IPv[46] Encapsulation, and "reference" column points to 2 ...
2
votes
3answers
171 views
Will pinging the multicast “all hosts” IP 224.0.0.1 fill my ARP cache with all hosts on my current subnet?
Just wondering in case I ever have a want / need to see all the hosts on my subnet.
2
votes
1answer
43 views
Typical signs of fragmented IP fragments
Given, for example, a Wireshark trace, how can I identify that the IP fragments that I am sending are themselves being fragmented?
For example, if I'm sending 1500 byte IP fragments, and the server ...
2
votes
1answer
133 views
How does NAT ensure that every machine has a unique public IP?
I am trying to understand the distinction between public and private IP addresses in IPv4 networking. The picture I've been told has some problems with it, so I would like to present it here and ask ...
16
votes
4answers
5k views
Why is 10.1.255.255 an invalid broadcast address?
I’ve been following the CCENT official certification book(100-105) and came upon this question in the “do I know this already?” quiz. The books only covered /24 subnetting only so far.
Which of the ...
1
vote
1answer
117 views
Can communication to broadcast 224.0.0.1 be made to reach hosts outside of the local subnet?
I been asked the question if it is possible for an a IP host to use multicast to address 224.0.0.1 in order to reach (and get a response from) another host which is not on the local network segment ...
0
votes
1answer
49 views
When IP header of length 22bytes is there then how padding will work?
My base IPv4 header of 20bytes + 2bytes i used for Options making it 22bytes means 176bits so padding will add 16 Zeroes to make it multiple of 32? is this correct way to understand?
Boundary of ...
0
votes
1answer
67 views
Which IPv4 options must be copied on fragmentation and why?
In RFC 791 page 14 it says
The copied flag indicates that this option is copied into all
fragments on fragmentation.
0 = not copied
1 = copied
If I understand correctly it is possible ...
-2
votes
2answers
401 views
What's the DF flag mean in IP packet header?
In the IP package, there is DF flag: Don't Fragment.
I have doubt about it, is it mean let all the L3 device do not to fragment the IP packet (if the L3 device found it is bigger than MTU, device ...
0
votes
2answers
21 views
Can 2 Directly connected PCs having the same network ID but different subnet mask talk? [duplicate]
If Pc1 has IP 192.168.10.2 / 24 ---> Network ID : 192.168.10.0
and Pc2 has IP 192.168.11.3 / 23 ---> Network ID : 192.168.10.0
directly connected (no switches no routers).
Why cant i ping?
But if ...
-1
votes
1answer
60 views
Floating Number representation for Ipv4 address
I'm wondering if we can have floating point(3.3 9.9 2.2 6.3) or Hexadecimal(6A.65.D5.77) representation for Ipv4 address that is also 32 bit long to compensate for IPv4 address shortage. Same ...
2
votes
1answer
485 views
Why the IPv4 need Don't fragment Flag?
Why the IPv4 need Don't fragment Flag?
We know the IPv4 Flags options are: Reserved bit, Don't fragment, More fragments, fragment offset options.
Why there need the Don't fragment Flag? if it is ...
1
vote
1answer
69 views
How to understand the Flags is IP_MF, what will happen?
For data packets whose length exceeds the MTU of the interface, fragmentation processing is required. The fields related to fragmentation in the IP header are as follows:
Identification - Used to ...
0
votes
4answers
167 views
How do devices connected to a switch get their IPs?
It should go without saying, I'm new and still learning about networking. One of the things I'm not clear on and couldn't find a satisfying answer to, although I've done some digging around, is how ...
3
votes
2answers
200 views
Global BGP Routing only by only importing supernet prefixes
I was wondering if global IPv4 Routing can be technically achieved only by importing from the ISP Provider (providing us with a IPv4 BGP full table) a subset from the BGPv4 routes (i.e. all prefixes ...
