Questions tagged [udp]

UDP (User Datagram Protocol) is a simple connectionless transmission model formally defined in RFC 768.

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Does openssl DTLS 1.0.2k takes fragmented input and reassemble fragmented packets? [migrated]

I am facing an issue where DTLS handshake packets are greater than 1500 bytes and I do fragment to make sure it is less than 1500 bytes. The fragmentation is as per RFC dictated. Now, when I check ...
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190 views

What is this service? [closed]

Fairly new to infosec and am going through a course on nmap. While scanning I found this and it looked interesting and was wondering if you all had any information on this? This is the port,state and ...
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429 views

Do I have to block UDP ports when I launch my own server with a public IP?

I am trying to give better security to my Raspberry sever. When I installed UFW, I allowed just port 80/tcp and my own high port for SSH communication, and by default are all others ports "deny". ...
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1answer
28 views

Why do processes on servers have socket types associated to the port number? [closed]

Why do some servers have TCP/UDP alongside the port they're listening to. To my understanding TCP and UDP are socket layers, they're methods of determining how the traffic is being sent over the ...
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What is the difference between DNS flood attack and UDP flood attack?

As title says, what is the difference between DNS flood attack and UDP flood attack? Plus, do they only exhaust the network bandwidth or do they also exhaust the server-side assets such as CPU, ...
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Encrypting UDP? (not using DTLS)

We are exploring options on encrypting messages to 3rd party devices which operate on UDP messages. Since each vendor will need to implement the encryption-decryption process as well, we would like ...
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2answers
282 views

How does DTLS replace the transport encryption of TLS? [duplicate]

I've been reading the RFC for DTLS over UDP, but can't seem to understand, how the transport encryption aspect of TLS was handled. It reads to me, like they just didn't bother, since there can be ...
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1answer
42 views

is -nU an option with nmap?

My coworkers seem to have -nU (no udp) as an option for their nmap scripts but I've never seen this in use and when I try to use this option with nmap, it does not work. I thought no udp was enabled ...
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112 views

One way protocol with encryption without tcp

I am trying to brainstorm how I might either: 1) create a protocol (although against this option) 2) use an existing protocol That does the following: 1) allows 1 way communication from 1 node to ...
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1answer
1k views

Vulnerabilities of DNS when utilized on a TCP port

There was some specific cyber security challenge (Cyber Cube 2018, GE). In one of the tasks, objective was to gain the access to some specific file that server included. After successfully solving ...
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Machine reaching out to Microsoft IP address using NBTstat command

I have limited logs for this event but the IPS says its a NBTstat query outbound over UDP port 137 to a Microsoft owned IP address. Should UDP 137 ever reach out externally? This is about all the ...
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1answer
156 views

Security implications of setting the broadcast flag on a UDP socket

Are there any negative security effects of setting the SO_BROADCAST option in a C UDP socket? I'm writing a C program and if I just set the broadcast option to 1 then all IP addresses work as intended,...
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886 views

UDP vs ICMP flood

How can we measure the efficiency of the flood technique? Will it be by the number of bots required for flooding the link? In case of UDP and ICMP, which one would be more efficient and why?
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434 views

Why is spoofing allowed in reputed VPS services?

I just learned about IP spoofing and so I set up VMs and sent spoofed UDP packets (8.8.8.8, Facebook's IP, Twitter's IP) to myself (home PC and mobile) from well-reputed VPS providers like AWS, ...
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2answers
933 views

How many UDP packets is too many?

My Company recently got hit by a spam email with a link that executed an .exe file. Apparently our Antivirus stopped it from executing (Symantec enterprise). I'm no security expert, but I am a ...
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UDP flood 300 Kbps + SYN probes / other attacks. Flood or DDoS at low rate?

So for over 2 weeks, Im receiving what appears a combination of attacks non-stop 24/7. First this UDP flood at a strangely small rate of 280 Kbps / 110 pps (360 bytes length) 02:29:41.978484 IP (tos ...
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Insecure/Obsolete TCP/UDP Ports? [closed]

I used CurrPorts to monitor TCP/IP network connections. This image shows when I don't connect to the Internet but I don't know why Avast Antivirus established this port. Is it insecure? This image ...
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1answer
145 views

How to handle UDP abnormally disconnection in DTLS?

DTLS-UDP is used between client and server. If the client ends abnormally,how does the server know that the client is gone? i have read rfc6347 and find nothing about that. thanks in advance.
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If TCP is more “secure” than UDP, how would a practical UDP “attack” look, for example during the initiation of a MS RDP connection?

In accordance to the recent question Why is TCP more secure than UDP?. How would an "attack" look when it comes to the practical aspect? A great example would be the use of TCP or UDP for Microsoft ...
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Why is TCP more secure than UDP?

During reading MS SDL presentations I found a recommendation to replace UDP by TCP in applications because TCP is more secure than UDP. But both of them are only transport layers, nothing more. So ...
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1answer
309 views

How to block an application with iptable which use random port

Scenario: My goal was to allow TeamViewer to connect to my home workstation from my laptop only. So I have tried to bind my laptop's MAC with an IPtables rule as following, [arif@arif:~]$ sudo ...
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Spoofing an IP/MAC address to avoid ICMP Destination Unreachable being sent back [duplicate]

As far as I understand UDP flooding the idea is to send UDP packets across all ports from e.g. Alice to Bob, and get Bob's machine to check who listens to certain ports and generate many ICMP ...
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754 views

Using IPsec through NAT

I have read that it is recommended to encapsulate IPsec packets into UDP (port 4500) packets in order to circumvent NAT. Could anyone please provide a detailed explanation of the reasons behind this ...
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2answers
870 views

Authenticate a user thru a UDP socket

so let's say I had a basic socket, doesn't give you any information about the user other than the IP address, what would be my options If I wanted to authenticate a user in the most optimal way ...
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2answers
1k views

Windows firewall settings to receive UDP and pings

I use a windows 10 to receive UDP packets or pings from another computer which runs Win/Mac/Linux. I default, I turn off the firewall to receive pings or packets. I prefer not to turn off the ...
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1answer
451 views

Is it possible to scan the top X UDP ports and the top Y (X!=Y) TCP ports in Nmap using a single command?

Given X!=Y, is there any way to scan the top (--top-ports) X TCP ports and the top Y UDP ports using a simple Nmap command? The --top-ports parameter affects both the TCP and UDP scans (e.g., when -...
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140 views

Does the choice of protocol affect the efficiency of a DOS attack?

I was wondering, to make a DOS attack you need to send something to the target you are DOS-ing. And to send something you need to use some protocol. My question is, are all protocols the same speed? ...
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2answers
4k views

How realistic is it to spoof a specific UDP IP address? [duplicate]

Let's say that I'm a malicious user Bob and I have found a vulnerability in an application that will allow me to impersonate another user, Alice. Alice is connected to 'X' server with her IP address (...
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1answer
203 views

Client security using UDP

Introduction I am currently trying to build up a networking layer for Unity from scratch. Currently I am testing the communication via UDP using Node.js for the server and the client. However I guess ...
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1answer
1k views

Is it possible to successfully send a spoofed UDP header with a completely unrelated source IP?

I've read that many networks use ingress/egress filtering to eliminate the number of spoofed UDP packets sent and received by their network. Given that network provides have been much more diligent ...
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1answer
269 views

What is UDP port 56183

We seen suspicious probing from source port 53 to destination port 56183. May I know what services use port 56183 (udp)?
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1answer
75 views

Is it possible to get All IP's that belongs to given zip code? [closed]

For this kind of things can use Country IP blocker , but it only gives whole country IP's, so what im asking is , Is there any way to get All IP's that belongs to given Zip code?
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1k views

Does a Server connecting to port 3544 pose an increased risk

I had look at the firewall logs and i can see my production server connects to microsoft (13.92.90.48) on UDP port 3544. A quick reading suggests this is to do with Teredo tunneling (IPV6 translation ...
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No authentication, AES encrypted JSON over UDP

I was recently assigned the task of testing a new hardware device which communicates with a JSON API over UDP. For some reason or another, it was decided that AES-CBC-128 should be used to encrypt ...
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2answers
96 views

Find DNS Server of an IP over Internet [closed]

I know that many clients in the same network has a same DNS (Most of time but it can be changed.) But is there anyway to understand what DNS Server that an specific IP (Over Internet) uses through ...
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2answers
696 views

Minimum required processes with open ports on AWS?

I recently started an AWS box to be used for a public web site and it seems to have the following ports open... I was long ago convinced that it's a good idea to minimize the attack surface on any box ...
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215 views

How does DTLS use a CBC cipher if the application data is not reliable over UDP?

From what I understand, when using DTLS, the TLS handshake is made reliable, but the transport of application data is not. I'm looking at a PCAP from the DTLS section of the Wireshark site. The ...
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1answer
518 views

UDP replay “attack”

Suppose that there is a client-server application using UDP and you have full control over client. The task is to automate few known actions on the client and make them very fast.(Possibly bypass ...
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1answer
135 views

Following strategy using DDoS mitigation service - UDP bandwith exhaustion attack from spoofed IPs

I need to defend against receiving a massive spam of UDP packets from random spoofed IP addresses. I would make it this way: In my protocol, every UDP packet contains username and password. Firewall(...
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2answers
777 views

How to deal with UDP bandwidth exhaustion DDoS attacks?

I am building a service, which will use UDP. It will run on Amazon AWS - in the firewall they provide, I can block everything except that one UDP port my service will run. The only thing I'm ...
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2answers
497 views

Do I have a IP leak if I use Tor and Skype/UDP?

I configure my OS so that it sends all traffic over the Tor (assume that, I configure Tor like proxy). I use Tor (which does not support UDP) and Skype (which uses UDP). My questions are: Does that ...
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282 views

Linux service on UDP ports under MITM or fuzzing attack

I am rather new to this forum but I will try my best to explain my situation. I run a game server for an outdated game called Project Reality. The community is rather small and the remaining servers ...
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2answers
658 views

IP leakage on Skype through VPN

Does anyone know how the traffic behaves if you configure a VPN natively through SSTP (WIN or MAC)? Because most applications use the TCP, but Skype uses UDP. I try to formulate more specific ...
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3answers
2k views

Why does our network firewall drop netbios-ns packets?

In our local domain environment, we use Sophos UTM to protect our network. When I check the firewall logs, I can see that a huge number of packets dropped by the firewall are netbios-ns (UDP 137) ...
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3answers
7k views

Is QUIC (Quick UDP Internet Connections) safe to allow through firewall?

Our firewall currently blocks QUIC (UDP 443) traffic which seems to be enabled by default in Google Chrome. Is it safe to allow QUIC or should I wait until it is implemented in all the major browsers? ...
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665 views

UDP flood from my own IP

A few moments ago I was trying to open Youtube when the browser (Chrome) notified me that I have no internet connection. All of my cable connections were OK. I disconnected the cable from my computer ...
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2k views

How is UDP hijacking even possible?

My doubt is this: UDP has no sequence numbers, so what indeed is the concept behind UDP session hijacking?
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405 views

Can data coming into my UDP server be sniffed?

I have made a small tracking device. I am trying to reduce the data overhead as much as possible to make the device very cheap to run. We are working on the basis that 1MB = £0.01 (the data price at ...
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Why is UDP port scanning slower than TCP port scanning?

I can't seem to find an answer for this. Any suggestions?
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177 views

Firewalled bots in UDP p2p botnets?

One thing that I don't understand about peer to peer botnets, is how a bot stays connected to the network considering the protocol used is UDP. Since the UDP is connectionless, and the bot is behind ...