Questions tagged [ipv4]

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

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Python - Raw sockets: IPV4 Packet cant be sent to public ips (Only working on local ips) [closed]

So... i decided to create my own raw sockets structure in python (It means i wanted to create my own raw ip packet)... The code: import socket, struct, sys ip = str(sys.argv[1]) def buildIP(): ver ...
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5answers
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What is the proper term for ipaddress/hostname:port

What is the proper term for (example) hostname.tld:433 (hostname:portnumber)? It is not just hostname, and it is not really a URL either :) same goes for 10.0.0.1:3306 etc.
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1answer
27 views

How does a packet know where its destination is? [duplicate]

When I connect to my friend's mobile Wi-Fi hotspot, we both have the same public IP address. Now, when I go to duck.com, how does DuckDuckGo know where to deliver the packets? I mean, I and my friend ...
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5answers
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What happens to the unused IP addresses in the subnet that falls in between two routers?

This is probably a un-realistic question, but a question nonetheless, that has been bugging me since quite a while now. Consider the below network diagram, where R1 is a part of a 10.0.0.0/8 network (...
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1answer
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What is the reason behind not returning unused IP addresses? [closed]

There are several companies out there with one or more /8 IP addresses, for example: DoD has more than 200 million, HP has one /8 (>16 million), Apple has one /8, General Electric has one /8, IBM ...
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1answer
40 views

Duplicate IP addresses on different "levels" of subnets

My question is quite simple: let us say there is a 10.0.0.0/8 with the subnet mask of 255.0.0.0 (first 8 bits used up for network address). Let us say, one address in our subnet is 10.0.0.1 (subnet ...
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3answers
12k views

Difference between IP checksum and TCP checksum

If an error on a packet occurs on a router, who does detect the error, IP checksum or TCP checksum? I have understood that the IPv4 checksum detects errors only inside the IP header and the TCP ...
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0answers
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Really new to Networking and wondering how the first 3 octets of 255 is 1 network [duplicate]

Watching this video on subnetting and I am kind of confused as to why the first 3 octets are all counted as one network but the last octet only adding 1 bit to it makes another network entierly. I'm ...
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3answers
2k views

DHCP Server Port-Based Address Allocation on Cisco switch 2960-x

I am trying to configure DHCP Server on a Cisco 2960-X switch to achieve port-based address allocation. I would like the IP address assigned to any device connected to that port to be the same every ...
72
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5answers
32k views

Is "IPv10" a joke or a serious RFC draft?

Internet Protocol version 10 (IPv10) Specification The name is funny (IPv4 + IPv6 == IPv10), but the actual proposal looks strange (one more packet format to battle incompatibility between packet ...
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2answers
76 views

What is the minimum MTU of IPv4 68 bytes or 576 bytes?

I read that 68 bytes is the minimum size of IPv4 datagram every device must be able to forward without further fragmentation. 576 bytes is the minimum size of IPv4 datagram every device has to be able ...
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2answers
64 views

network IP packet format

i completely understand that why receiver there is 576 bytes but my question is as technology update every after one Minutes then why we can't update that limit [enter link description here][1]
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1answer
519 views

Which one right, UDP has 508 or 512 bytes payload limits?

We know the size guarantees the datagram won't be fragmented in IPv4 is maximum 576 bytes. But the size when use UDP header 8 bytes and if we take UDP payload 512 bytes and choose maximum header size ...
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9answers
89k views

Reason for both a MAC and an IP address

If my computer has an IP address,why does it need a MAC address?
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2answers
14k 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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1answer
35 views

Do IPv6 addresses have better persistence with DHCPv6?

I have a LAN with about 25 devices that occasionally grab each other's IP address via DHCPv4. I know there are certain lease time limits and it can be set to very long periods to work it around to an ...
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1answer
86 views

Are IPv4 type of service and IPv6 traffic class equivalent to each other or is traffic class IPv6 specific? [duplicate]

IPv6 has a traffic class field. According to the specification it is an IPv6 length, out of which first 6 bits are called code point or differential services code point (DSCP) and the last 2 bits are ...
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1answer
62 views

Why UDP checksum is optional for IPv4?

We know that IPv4 header has checksum for header not for data .Therefore for checking data error we need checksum in transport layer. Suppose we're using UDP in layer 4. So if I remove the checksum ...
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1answer
77 views

How to tell if an ipv4 address is public or private?

I've read the below thing, in a website. According to standards set forth in Internet Engineering Task Force (IETF) document RFC-1918 , the following IPv4 address ranges are reserved by the IANA for ...
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2answers
468 views

Why are Internet hosts "not required" to receive an IPv4 datagram larger than 576 bytes?

I'm currently studying Internet protocols and had a question regarding the IP datagram. Within the IP header I am aware there is a field called "total length" which specifies the total ...
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1answer
69 views

Why the pseudo-header is not transmitted with the UDP datagram?

I have read from E. Comer - Internetworking with TCP/IP 4th edition that "The purpose of using a pseudo-header is to verify that the UDP datagram has reached its correct destination. The key to ...
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1answer
44 views

UDP checksum calculation for checksum results in the value zero

I read UDP checksum from Wikipedia that "If the checksum calculation results in the value zero (all 16 bits 0) it should be sent as the one's complement (all 1s) as a zero-value checksum ...
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1answer
41 views

How UDP checksum get IP address to make pseudo header in transport layer?

We know that UDP checksum's pseudo header contains the most important parts of the IP header, that is, source and destination address, protocol number and data length. I hope that the concept of IP ...
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1answer
21 views

SNMPv2 to v3 conversion

Can I use a Cisco router to convert SNMPv2 from an end device in one network to SNMPv3 and the C&M software in another network? The end device can only handle SNMPv2, but the C&M community is ...
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2answers
184 views

Why can IPv4 and IPv6 use strict source routing(in options field) and flow label respectively inspite of connectionless protocol?

In IPv4 option field one field option is source routing option this means packet will always be routed by router Or not. Packet can also be routed by source such routing is known as source routing. ...
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2answers
85 views

Is it possible for TCP can accept out of order segments?

TCP is connection-oriented protocol whereas IP isn't connection-oriented protocol. Any packets before sending into transport layer sorted operation must have been done in network layer. That's why we ...
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2answers
33 views

Do routers overwrite options of IP packets?

If i use IP options to send secret messages outside of the network using for example EIP, will the router replace them before sending out to the internet?
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1answer
157 views

Ping to default gateway failing

I am trying to ping to a default gateway which i have configured as 171.2.0.1 but somehow the ping is failing . I am new to network domain so i have less idea about it . Any help is appreciated .This ...
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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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1answer
63 views

Does IPv4 of all devices follow this standard xxx.xxx.x.x?

I think the title says it all. I haven't found the answer anywhere else on the internet.
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2answers
46 views

Ping a host on the same network with special IP 0.0.0.0/8

I am trying to ping the host 192.168.1.5 from my computer. This works good. The subnet mask of the IP is 255.255.255.0, so the private IP 0.0.0.5 can also be used to ping the same host. But that ...
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2answers
118 views

Class D network for multicasting between group

We know Multicasting is defined as a single source sending to multiple recipients on a network when the receiver broadcasts a signal for acceptance. Multicasting has its own Class D IP addressing ...
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3answers
714 views

Connection between 2 end devices with different subnet masks (Packet Tracer)

I was just wondering why Packet Tracer allows 2 end devices to ping each other even though they're specced with 2 different subnet masks? am i missing something here? i.e. PC1: 192.168.1.10/24 PC2: ...
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1answer
138 views

"SWIP" Equivalent for RIPE?

With ARIN, I was familiar with using "SWIP" for IP blocks via an ORG and a POC. With RIPE, however, it seems that it's different. I have access to a RIPE account where I can make the changes,...
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2answers
63k views

Why is my Router's WAN IP different from public IP? [closed]

My Router's WAN IP is a public IP - 172.100.x.x And my public IP is - 182.x.x.x Why do I have 2 public IP's? Does this probably mean that my router is behind another router? But then what is the use ...
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2answers
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Can I assign one of my publicly available IP address to my AWS instance?

I would like to be able to use one of my publicly accessible ip addresses directly with my aws cloud instance. Is there a way I can assign or transfer one of my ip address to aws? My ARIN registry ...
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0answers
16 views

Do any subnets "Network ID" AKA "Network Address" always have an even number as the last octet? [duplicate]

Should a subnet have a "Network ID" AKA "Network Address" (eg: the first address, which is always unusable, and is the boundary between the previous subnet and the current subnet) ...
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1answer
40 views

Are routers doing NATP possibly run out of ports?

NATP helps each connection on the client device gain a "temporary identity" on the internet, by maintaining a one-to-one relationship between its local ip-port to a WAN ip-port. The binding ...
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3answers
347 views

Questions about NAT

So i just started learning about NAT and networking in general. As powerful as this technology may seem, it was specifically made for reducing the amount of IPV4 addresses used throughout the internet,...
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2answers
4k views

What is IP squat space

I came across this article and I'm trying to understand what is going on here, I found some packets on my network containing 22.0.0.0/8 and 29.0.0.0/8 IP range and It's based on: https://en.wikipedia....
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1answer
26 views

how does a host learn about other hosts IP addresses connected on the same subnet? [duplicate]

My question is similar to one posted [here][1] But answers are not understandable to me. How can a host (say my laptop) learn about IP addresses of other devices (say my phone) on the same subnet. ...
4
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1answer
107 views

What are the negative impacts of using non RFC1918 addresses on a private network?

I work for a company overseeing network design of a large industrial system. For our purposes, it's a backbone network that other stakeholders have their own L3VPNs defined on. It is a network with ...
2
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1answer
31 views

Assigning static IP address from the DHCP pool range on Cisco 800 series

What happens if I assign a static IP address to a device in a LAN where there is an active DHCP server and the address falls within the configured DHCP pool and DHCP server is Cisco 800 Series? Most ...
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3answers
4k views

Where do the layers of the OSI Model operate in the operating system?

The OSI model describes them as layers. But where do these layers actually operate in the operating system? For example, where and what actually does TCP? All these layers are described as using ...
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1answer
63 views

I cant ping across Lan?

Current configuration : 2695 bytes ! version 15.1 no service timestamps log datetime msec no service timestamps debug datetime msec service password-encryption ! hostname ...
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2answers
49 views

How does RIRs actually ensure IP ranges ownership

I'm currently learning about CIDR, subnets and IPv4 classes. I understood that IPv4 classes were used to route traffic in the beginning but nowadays we use "dynamic" subnet masks with the ...
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2answers
59 views

Are the IPv4 datagram addresses the corresponding public addresses, or the private addresses?

Inside the IPv4 datagram, there are the source and destination IP addresses. The first indicates the IPv4 of the source host, and the second indicates the IPv4 of the destination host. Are these ...
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1answer
69 views

How does a device receive default gateway IP address?

When and how does a device get information about default gateway in LAN? I know you can define default gateway statically, but which protocol is used when it is not statically defined? Is it from ...
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0answers
735 views

Logical-Tunnel Interface Juniper MX 480 doesn't "work"

I have configured a logical tunnel between my master-routing-instance and a additional routing-instance. I tested the same config (except IP addresses) on my lab-system and on one of our other core-...
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0answers
12 views

Divide IPv4 network into subnets in a SPECIFIC order [duplicate]

My private addresses start at 10.10.0.0/16. I must make 2 subnets with 120 and 450 starting with the 120 one and not leaving any unnecessarily unused addresses. Let me remark, it's IMPERATIVE that the ...

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