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Questions tagged [tcp]

Transmission Control Protocol (TCP) is a transport layer protocol that provides a connection-oriented data stream service with guaranteed, in-order delivery.

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Leaving half open or full open connection having SYN cookie

Suppose an attacker collects a large number of initial sequence numbers sent by the server. Can the attacker cause the server to create many fully open connections by sending ACKs with those initial ...
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Creating half open or full open connection in presence of SYN cookie

Suppose an attacker knows that a target host uses SYN cookies. Can the attacker create half-open or fully open connections by simply sending an ACK packet to the target? Why or why not?
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Detect port forwarding

If there are 3 machines A, B and C and A communicate directly with B (A -> B) but B is executing port fordwarding with the next command socat TCP4-LISTEN:443,fork TCP4:<ip machine C>:443 So ...
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Spoofing TCP/IP headers and uniqueness of the host name

I have some related questions: Is it possible to spoof the source address in the TCP/IP header when using HTTPS? If possible, is there any way to detect source address change? I think the checksum is ...
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SCP to create security groups in member AWS account

I'm trying to create a SCP to restrict member account users to create/modify security group(s) that have inbound rule for SSH/RDP with Source set as 0.0.0.0 or ::/0. Basically, I want users to SSH ...
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Repeated DUP ACK and RST to same TCP SEQ and ACK

I started noticing this behaviour for more than a month. Whenever I connect my laptop to the WiFi router there are lots of RST and DUP ACKs up to the same TCP sequence, as given in the example below, ...
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The router (that my PC is connected to) is continuously attempting to connect through TCP80. What would be the reasons?

I have no access to the router nor do I have any administrative access to this local network. But every 5 minutes the router attempts to connect to my PC through port 80/tcp, and it attempts exactly 4 ...
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Comparing Wireguard to IPsec: Is Wireguard working like transport- or tunnel-mode?

I'm deeper into different VPN technologies for university and wondering, how Wireguard is handling the IP-packets (header and payload) compared to IPsec's tunnel and transport mode. May someone ...
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TCP SYN/ACK on INPUT vs FORWARD

Are there any legitimate circumstances under which TCP SYN+ACK packets would arrive at a Linux firewall's INPUT chain, if it did not leave via the OUTPUT chain? That is, am I correct in assuming that ...
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How to properly secure a tcp server/client application

I have developed a multithreaded server/client python application, my next goal is to encrypt the traffic between both parties but I can't tell where should I invest all my research energy in Using ...
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1 answer
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Can my ISP or government listen to my Skype calls?

Is the call encrypted with something like HTTPS to prevent a corrupt government (or ISP) from messing with the DNS routing, sniffing, snooping etc? Can my ISP or government listen to my Skype calls? I'...
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2 votes
2 answers
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Is an open TCP port that doesn’t take input secure?

I have written a simple C program (~30 lines) that opens an internet socket and sends data to the client on every connection. The program never read()s from the socket; it just parses the /proc ...
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ARP spoofing on TCP and UDP

Statement (In Interview): ARP spoofing attacks are more effective for UDP packets rather than TCP packets since TCP establishes reliable communication channels. I have opposed the statement saying ...
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2 votes
1 answer
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Is this TCP socket encryption and password storage implementations secure enough?

I'd like to know if this communication technique is secure enough against attacks, both on the connection itself and the password-storing procedures. Both the client and the server have access to 2 ...
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Can't find anomalies / abnormalities in wireshark capture

Previous post was deleted for not enough context, which I apologise for. I will try to provide as much context as I can. I am aware this appears to be an example of a SYN flood attack with spoofed ip ...
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Tool for injecting data in existing tcp connection

I would like to perform arp spoofing on an existing tcp connection between a server and a client and perform a mitm attack. In addition to altering existing packets, I would like to be able to inject ...
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28 votes
3 answers
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Disadvantages of replacing TCP/IP with blockchain

I read this blog (cached version) (and the related cached tweet) about replacing TCP/IP with blockchain. Tweet: The Internet has a serious fundamental flaw: the transmission control protocol/internet ...
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Real-world application of network steganography

I recently came across a topic of network steganography, mostly connected with modifying the headers of IP, TCP, ICMP. I was looking for some real-world examples of malware that uses it. I only found ...
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Can Mirai scan reach devices behind routers?

I recently saw this article of a version of Mirai being spread to Android based devices via ADB enabled. My question relates to how Mirai does scanning. Lets assume I have a Android based device (like ...
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3 votes
3 answers
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What prevents this specific type of attack from being viable?

Imagine a user has an ip of 1.2.3.4 The server the user intends to connect to has an ip of 2.3.4.5 An attacker has a machine with a promiscuous network card on the user's local network. The attacker ...
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Why ACK flood is effective?

I understand that SYN flood is effective due to how protocol works, waiting around 75 seconds before closing the connection. What about ACK flood, what does it happen on the destination side that ...
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What is insecure about the "insecure" option of NFS exports?

Why is it considered insecure for an NFS export to allow connections originating from high ports? Compare the manual: exportfs understands the following export options: secure This option requires ...
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Spoof IP address after a TCP handshake established

Is it possible to spoof the IP once a TCP handshake was performed successfully? For example: Perform the handshake Use the session with the same IP which performed handshake but on different machine ...
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How to identify the usage of the tcp/ip Trek Stack

In order to mitigate the potential exposure to ripple20 zero-day, I must identify the device/s that have the Trek TCP/IP stack installed. Can I do this with software like LanSweeper? Or must I check ...
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1 answer
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Decoding TCP Packet in wireshark [closed]

There is a small piece of code that is making request to Web server through socket. i am able to see that its a TCP over no SSL through wireshark. My question is, Is it technically possible to see ...
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IPC Security on Server [duplicate]

An application is running in a customer's environment on a single server and consists of a collection of Windows Services that communicate with each other using (unencrypted) TCP messages. Although ...
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Suricata - How to use TCP Flags?

I wrote the following rules: alert tcp any any -> 192.168.6.4 any (msg:"SYN"; flags: S;) alert tcp any any -> 192.168.6.4 any (msg:"FIN"; flags: F;) The SYN rule is matching....
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How can I ascertain that .NET NegotiateStream [MS-NNS] established a secure connection?

I have a WCF (Windows Communication Foundation) application using the netTcpBinding. Server configuration: <netTcpBinding> <binding name="defaultNetTcpBinding"> <...
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1 vote
1 answer
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Outgoing messages while under massive denial-of-service attack

As I understand it, there is no internet protocol that provides true broadcast like in say a card game or a partially synchronous network assumption. How close can internet protocols come though? We'...
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Intensive 586 (ms-shuttle) port scan/exploit/hacking attempts

Recently i wanted to play a bit with TCP/UDP networking (and touch some custom HTTP server impl) on C# and found out that i'm getting requests from totally unknown dudes, such as this one: FROM: [::...
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1 vote
1 answer
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Intercepting TLS 1.2 connections

I have an application that communicates with the server through a TCP TLS 1.2 connection. The app probably uses certificate pinning. I want to intercept this traffic. Is there any way to decrypt the ...
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Is TCP's 3-way handshake a kind of mutual authentication?

Assuming no one is able to inspect or MITM in the network. Can I see it as a way to ensure the source IP in packet's header is the real source of the packet, so a kind of authentication ?
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How To Validate Secure Traffic from Chrome with Element To Matrix.org on Linux

Are you familiar with the Element chat system of https://app.element.io ? Are you familiar with its connections to Matrix.org (for a free account)? Is there a way that I can sniff this traffic on the ...
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Exposing different services on the same port

My current project contains multiple heterogeneous TCP servers, but our IT guys have clearly declared that they will give me only one 443 port, which is fair enough. Two options are on the table now. ...
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2 answers
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Does an attacker need to guess or brute-force a password for TCP spoofing?

From my understanding, TCP spoofing can be carried out if the attacker can correctly guess the sequence numbers from the response packets (to mimic the real client). The attacker may even obtain this ...
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How Can I Prevent Hackers From Spoofing TCP messages onto my server?

I have a Python client and server communicating over a TCP socket - they send and receive a certain set of standardized string commands to each other. How can I prevent a hacker from creating their ...
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How to Spoof JA3 Signature?

I am using python requests library to make HTTP calls. However website bot detection is using JA3 fingerprint verification and blocking me. Is there any way I can spoof the JA3 signature.
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HTTP/3 No more TLS or TCP [closed]

I was reading documentation about HTTP/3, and in the article, they sed that they are no longer TLS or TCP. So it's mean that a web site with no SSL 80 will be changed to what port and 443 will be ...
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1 vote
1 answer
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Meterpreter Session died [Bwapp]

I just set up a lab with bwapp and wanted to jump straight into webshell. I used Unrestricted file upload vuln --> uploaded my perfect shell created with msfvenom. My only problem is that my ...
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What happens if a sender changes the TCP window size over multiple packets that have the same ACK number?

I'm currently doing research on evasion attacks that seek to bypass a Deep-learning based Network Intrusion Detection System. In order to achieve this, I need to know what the constraints are for the ...
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1 vote
1 answer
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Can TLS defeat the manipulation of TCP sequence numbers?

Assuming there is a powerful adversary who can arbitrarily manipulate the sequence number of each tcp packet, then the following packet-reorder attack should be possible, right? Assuming the packet ...
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Bettercap TCP proxy upstream server

I am using bettercap command line to perform a Man in the Middle attack on my LAN network with an EDUCATIONAL purpose (of course!). I want to intercept the TCP traffic, with the intention to view on ...
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1 vote
1 answer
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How to avoid password TCP message sniffing and subsequent hijacking

I'm developing a TCP Streaming API for "IoT" devices in LabView. The TCP Server will be listening to a certain port, and our devices will try to connect to it. In order to know that the connecting ...
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1 answer
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Does the DICOM file header gets lost when transferred over the network?

I am currently investigating the PEDICOM vulnerability CVE-2019-11687 where I am trying to reassemble the P-DATA DICOM fragments from a PCAP. Since the vulnerability takes advantage of writing bytes ...
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2 answers
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When connecting via SSH, does the Diffie-Hellman key exchange take place over an unencrypted TCP session or does encryption occur before the exchange?

I'm a cybersecurity student and I'm eager to understand the basic processes of an SSH session. I wrote down the stages to the best of my ability but need help understanding what happens right after ...
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1 vote
2 answers
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What is the most powerful type of DDOS/DOS attack? [closed]

What I mean is what protocol are best to DOS something like TCP, UDP, HTTP?
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What is bindshell backdoor?

I just found out a bindshell backdoor, but I don't know how to access/connect to it using Metasploit. I'm a beginner with exploiting; is there a way to access the backdoor? I tried to search for "...
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2 votes
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Microsoft DS vulnerability?

I heard that Microsoft DS is a port that is commonly used by hackers to hack computers due to its ability to transfer files. How do they transfer files with Microsoft DS? Do they need an exploit to ...
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3 answers
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Is TCP Port 80 (HTTP) vulnerable?

I heard hackers' top ports to hack computers through are port 80 and port 443. How do they do this though aren't port 80 and port 443 just for HTTP requests such as GET, POST?
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How to decrypt Diffie-Hellman in wireshark?

How can i decrypt Diffie-hellman TCP packets? I'm trying to make a tool that shows cleartext response from a server that uses this encryption. However when i look online people all seem to say it's ...
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