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Questions tagged [ip]

For questions about Internet Protocol (IP), an OSI layer-3 network protocol. There are two current IP versions in use: IPv4 and IPv6.

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Linux netfilter: How can i capture and modify packets going to a specific ip? [closed]

I am trying to write a linux service that captures the packets that go to a specific destination and performs necessary changes to them. More specifically, i want to find all of the tcp segments that ...
abe_carmgl's user avatar
0 votes
1 answer
51 views

Why is IPsec transport mode "vulnerable" for not having integrity of variable fields? Why is this so important?

With IPsec transport mode we CAN'T have integrity of variable fields (eg TTL and checksum). Why is it a problem? Is it? What could be the attack? I think TTL expire or checksum modification (so both ...
allexj's user avatar
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1 answer
48 views

Could address be omitted from packet in IPv4 if router is sending to / from that address?

Imagine an IPv4 packet routed like this: A -> Router1 -> Router2 -> B When constructing a packet per the structure, it seems A will have to include both source address (A) and destination ...
Mario Ishac's user avatar
3 votes
2 answers
704 views

In IPv4 Fragmentation, should the first block be necessarily the closest smaller multiple to 8

Is it mentioned in any RFC's that when one is splitting a Datagram into fragments, the bytes in the first fragment should be "the closest multiple of 8" or is it just a standard ...
mrtechtroid's user avatar
0 votes
1 answer
55 views

How localhost and its opposite 0.0.0.0.0 works

Here I am running an application on a computer, host=localhost, the application runs on localhost:5000, or 127.0.0.1:5000. When the computer accesses 127.0.0.0/8, or 127.0.0.0 subnet mask 255.0.0.0, ...
hodini's user avatar
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-1 votes
0 answers
12 views

Perform subnetting and assigning address to host [duplicate]

Question : An organization is granted the following block of address 200.166.16.69/18. The organization need to create 10 subnets from the block. Perform sub netting and assign addresses to hosts. ...
Ankit Chauhan's user avatar
1 vote
2 answers
69 views

What exactly does the term "main network" mean in subnetting?

In the computer networks course, we solve subnetting questions together with the teacher. There is a term we call the "main network". As far as I understand, we fill in this according to ...
Furkan KARADENİZ's user avatar
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0 answers
20 views

GSM and LTE-M connection with SIM7070G for MQTT data transmission

I am working on a tracker project using the SIM7070G modem from SIMCOM. The objective is to maximize the connection by working with both LTE-M and GSM, aiming to send location data via MQTT. I have ...
Santiago Mercante's user avatar
4 votes
5 answers
2k views

The Reasoning Behind TCP and UDP Multiplexing Tuple

I understand that TCP and UDP are multiplexed protocols, and the multiplexing key in them is the (sender.ip, sender.port, receiver.ip, receiver.port) tuple. I understand the reasoning behind sender.ip,...
Soroush Sherafat's user avatar
0 votes
2 answers
82 views

Do destination hosts decrement the TTL?

I was trying to understand more about traceroute when I stumbled upon this site and I have a question about this diagram: As you can see in the diagram, the destination host S1 receives a packet ...
Noob_Guy's user avatar
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2 answers
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What TTL value should i use to make sure the packet never leaves the broadcast domain

If i put the TTL as 0, will it never leave my broadcast domain? If I wanna send something to someone in my broadcast domain, can the ttl be 0 or will it still be dropped? Or should it be 1?
Tomas Ramos's user avatar
0 votes
1 answer
119 views

Too many mac addresses in a switch - Cisco Packet Tracer

The image of a network im refering to is above. In Cisco Packet Tracer after having used a command ping 192.168.1.3 from pc1 to pc3, when I check mac addresses in both SW1 and SW2 using show mac ...
pieceofpaper's user avatar
1 vote
1 answer
79 views

Why can't we use large-scale NAT system with thousands of private IP addresses assigned to a single public IP

Instead of assigning everyone an individual public IP address, could we use a very strong NAT system with thousands of private IPs behind a single public IP? This could reduce public IP demand and ...
Arash Seifi's user avatar
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69 views

End to end delay over N link including the (simplified) propagation delay

It is well know (see this question) and easily verifiable that end-to-end delay in case of trasmission of P packets of size L over N equal links (same transmission rate R) with zero propagation delay ...
frhack's user avatar
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1 answer
46 views

Is a private network the same concept as a network which uses private IP addresses inside it?

Kurose's TopDown Network book says: 8.7.1 IPsec and Virtual Private Networks (VPNs) An institution that extends over multiple geographical regions often desires its own IP network, so that its hosts ...
Tim's user avatar
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1 answer
88 views

How can I have multiple servers and IPs if I only have 1 ip with gigabit connection?

I have 1 gigabit connection with static public IP address... Without depending on my local ISPs colaboration, is it possible to buy IPs from an online service and route each individual IP to my local ...
adrianTNT's user avatar
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1 answer
74 views

IP fragmentation and PMTUD

I have 2 questions. 1) According to a lot of sources, when IP packets gets fragmented, in this case, lets take icmp, the icmp header is present only in the first packet. But I have observed on some ...
RRHS's user avatar
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1 vote
1 answer
78 views

Would a /24 public ip range typically be from the same country?

Would a /24 public ip range typically be from the same country? This to reduce the amount of ipstack requests, checking from what country an IP is. (due to bot requests)
MichaelD's user avatar
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0 answers
19 views

Why the length of IP address is fixed? [duplicate]

Is there technically reason for the fact that the length of IP address need be fixed? Now IPv4 address is 32 bits and IPv6 128 bits. If IP address doesn't need fixed length, we would can structure IPs ...
worner's user avatar
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0 votes
1 answer
62 views

What is hiearchy of IP addresses? [duplicate]

What is structure/hiearchy of IP addresses? I mean, is mandatory that IP address e.g. 216.9.10.0 is subnet of 216.9.0.0? Of course many times that is the case and IMO it would be logical, but I have ...
worner's user avatar
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1 vote
1 answer
80 views

The TTL and packet drop [duplicate]

I would just like to verify one thing. When a router receives a packet with a TTL of 1, the router can still process and accept it if its destined for itself, correct? Because for example, eBGP ...
Mitrixsen's user avatar
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-1 votes
1 answer
40 views

ISP ARP tables and routing [closed]

So I'm Network+ certified and have a beginners understanding of how network communication works, my head starts to split a bit though when I think about how the information is actually communicated ...
user1047228's user avatar
0 votes
1 answer
53 views

Can two separate computers connect over 127.X.X.X IP range? [duplicate]

Is it possible to set two computers (each have one lan interface) to communicate over 127.X.X.X IP range (e.g. one PC 127.15.0.1 and the other 127.15.0.2) +-----------+127.15.0.1+-----------+ | MyPC ...
DEKKER's user avatar
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0 votes
1 answer
102 views

Layer 3 Switch IP Problem on Packet Tracer

I set up a network. It contains vlans. I assigned devices ip addresses from different subnets. I have 2 layer 3 switches to communicate them. I assigned switches ip addresses from different subnet. I ...
shiva13's user avatar
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1 answer
42 views

Simple question about NAT [duplicate]

So I am learning about NAT. I understand that it changes IP from public>private and vice versa. From my understanding, when a packet or info gets sent to the public ip towards the private ip, ...
yea im a noob's user avatar
0 votes
1 answer
171 views

Basic Networking - IP address

guys, I am currently going through basic networking concepts... There is this piece of information: 'Briefly, an IP address (or Internet Protocol) address can be used as a way of identifying a host on ...
Jan's user avatar
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0 votes
1 answer
78 views

No access to internet via DHCP, but works with manual IPs

My DHCP server was giving out IPs in the range 10.0.0.1/24, but I ran out of usable IPs, so I changed the subnet to 10.0.1/21 to have more available addresses, however I am now having a weird problem: ...
Mike's user avatar
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0 votes
2 answers
83 views

Advertising IP prefixes to the internet using BGP

I am studying BGP at the moment. From what I've learned, in order to participate in routing on the internet and use BGP, we need to register a public provider-independent IP address block and a public ...
Mitrixsen's user avatar
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1 vote
1 answer
41 views

RIP v2 Network Command

I am comparing the Boson ExSim Lab to the Neil Anderson's Lab on RIP. On one of the labs on Boson ExSim, it asks to configure RIP on the routers, all of which are on some form of a 192.168..0.0/24 ...
Gyd-4nc3's user avatar
0 votes
1 answer
38 views

What does "Configure kernels to not follow the RFC 5681 SHOULD" mean?

Netflix documentary The Playlist about Spotify, they present one of the technical breakthroughs that they created their own TCP implementation to reduce the latency from first click to playing the ...
zirkelc's user avatar
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0 votes
1 answer
46 views

How to prevent a user from using YouTube while connected to my network [closed]

i need to restrick specific user from using youtube and other socialmedia during job time
Kapala's user avatar
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1 vote
1 answer
222 views

Understanding IPv4 model of operation

I'm new to networking and reading RFC791 about IP protocol specification and got some question regarding the paragraph 2.2 Model of Operation. Here is what is discribed: The internet module prepares a ...
Some Name's user avatar
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0 votes
1 answer
319 views

IP and Ethernet endianness

I'm completely new to the topic, I've read that Ethernet sends Bytes in a Big-Endian way, but that bits are sent with Little-Endian. I've also read that IPv4 uses Big_endian order. So my question is, ...
mizius's user avatar
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1 vote
1 answer
78 views

Recognizing the next protocol in MPLS header

How can I know what is the next protocol in MPLS header? I do know that MPLS header does not provide any information about the next protocol, But I somehow need to know how to recognize it, as I am ...
user89902's user avatar
0 votes
2 answers
169 views

does routers use MAC addresses to map request/response?

we know that Local machines use private ip address inside a company and share a single public ip address when communicate to the outside world, so does routers use MAC addresses to map request/...
whoisit's user avatar
0 votes
1 answer
641 views

Why Linux answers ARP requests for IPs that belong to different network interfaces? [closed]

My machine has a physical network interface (eno1) and a bunch of virtual network interfaces (e.g. tap0). Each interface has its own IP and their subnets do not overlap. I noticed that if I perform an ...
felipeek's user avatar
  • 103
1 vote
2 answers
79 views

How did ATM switches that were implemented in a core of IP network improve QoS and higher data rate?

How can ATM switch improve Quality of service and data rate just by incorporating them into the core of IP network? What was used in the sore of IP networks before ATM switches and what is used today ...
Vladimir Pejanovic's user avatar
1 vote
2 answers
356 views

How does subnetting solve the problem of IPv4 address shortage?

Reading articles on the web, they all say that "subnetting solves the problem of IPv4 address shortage by dividing a large physical network into multiple smaller networks". I do not ...
penguin99's user avatar
  • 135
1 vote
1 answer
70 views

Why does a PIM DM assert loser reply with a prune?

In PIM Dense Mode, why does an Assert loser send a Prune message to the winner? What is the actual motivation for this?
Marcus's user avatar
  • 183
0 votes
1 answer
990 views

Not able to ping device with different subnet on gateway and ip adress

I am trying to ping a device with IP 192.168.0.200, subnet mask 255.255.255.0. It is configured with gateway adress 192.168.1.1. Is it because the gateway subnet, and ip adress subnet is different i ...
alehol's user avatar
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1 vote
0 answers
29 views

What are the triggers for PIM-DM prune and assert messages?

There are articles explaining the PIM-DM mechanics, and they only confused me. Considering the most common topology, that of three routers, connected to each other like a triangle as such: R1 -- R2 \ ...
Marcus's user avatar
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0 votes
2 answers
50 views

Hop 1 of the traceroute to Internet is not the gateway [closed]

I'm assigned to a public IP address from my organization. Here is my default route: IP: 45.150.164.x Gateway: 45.150.164.1 netmask: 255.255.255.0 And here is the result of traceroute 8.8.8.8 from my ...
wyb's user avatar
  • 9
0 votes
1 answer
1k views

Sharing same IP address inside LAN? [duplicate]

Q: if 2 devices A and B share same ip address in LAN, can device A retrive all messages whose destination is device B? I think this depends on how the LAN is configured. If it's wireless then device A ...
Albert's user avatar
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0 votes
1 answer
493 views

The relationship between IP address and AS number

I've recently been looking for the IP prefixes originating from a specific AS. And there are a few questions I'd like to get confirmed. We can register IP addresses and ASN from RIR. But where can we ...
wyb's user avatar
  • 9
0 votes
2 answers
314 views

Connecting L3 and L2 switches with VLAN settings

I have 1 L3 switch with Static ip - 192.168.0.252 Two L2 switches Switch A - 192.168.0.250 Switch B - 192.168.0.251 I have created VLANs in L3 switches with 192.168.1.1 and 192.168.2.2 ips abd set it ...
Arahasya's user avatar
  • 101
0 votes
1 answer
22 views

Detect the use of a VPN connection _to_ a box by traffic coming _from_ the box [closed]

Imagine that we have three boxes: A <--(VPN)--> B <--(public internet)--> C A and B are connected via a VPN. B and C are connected via the public internet. Let's assume that A and B run ...
9000's user avatar
  • 103
0 votes
1 answer
38 views

Can anyone explain what the numbers at the top of this IP Header diagram represent?

… and what is the significance of the grouping? many thanks!
TimPowders's user avatar
0 votes
1 answer
226 views

What are all the reasons for using a separate /31 subnet for a p2p link?

For example in this LAN, the 13.65 and 13.66 are a separate subnet between slip and bsdi, but what is the reason that they have a separate subnet? The only reason i can think of is that bsdi cant have ...
user87014's user avatar
2 votes
3 answers
802 views

How to obtain a range of IPv4 or IPv6 addresses as an individual

I am building a hobby service that can host user's containerized applications on request. These must be publicly accessible. After some googling I came to conclusion that there is no way around having ...
jlkiri's user avatar
  • 21
1 vote
0 answers
15 views

How to specify the address of the host in IPv4? [duplicate]

Lets say the IPv4 address is: 192.168.50.112 /26 which provides 4 subnets subnet mask: 255.255.255.192 network address 192.168.50.64/26 There are 6 bits left for the Host, how do you specify the host ...
20MikeMike's user avatar

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