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.

19 questions with no upvoted or accepted answers
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TCP Sack panic proof of concept?

For the vulnerability called TCP SACK panic([1], [2], [3], and many more): is there a proof of concept code out there that can be used to test vulnerability status and effectiveness of remedies? [1] ...
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88 views

Sniffing TCP packets using Wireshark

I am trying to reverse engineer a decoder. To do so I need to sniff the packets that the decoder receives from an Android application installed on my phone, this application is what controls the ...
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3answers
339 views

Secure preshared key 2 way authentication

I have the following setup: A server and a client will be connected over tcp. The server and client both have access to the preshared secret key. When the client connects to the server, the client and ...
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636 views

Inconsistent duplicate TCP packets

How often does it happen that we benignly see a TCP packet that is retransmitted but has a different payload the second time? In other words, how often is it that we see a TCP packet with sequence ...
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1answer
104 views

What ports are okay to be open on a macbook pro?

When I do a network scan for open ports on my MacBook Pro, I can see the following open TCP ports below. Are these 'standard' open port for a personal computer of this type? Should I be concerned? ...
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72 views

network ports are filtered strangely?

I have some Ubuntu servers deployed in VULTR Global Cloud and I have about 300 network ports each server. However, every server will be filtered in China suddenly (I can ping from China). I use nmap ...
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0answers
2k views

Decode TCP stream captured on WIreshark

I have captured user and password credentials (in an internal network) sent from my computer to another host in a pcap file. I thought that I would be able to see the data in cleartext as there are ...
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0answers
29 views

Control TCP access by user

I have a Windows 2008 R2 server in an intranet that has a TCP port open and client machines connect to from their software. Without intervening in the application to restrict the access only to ...
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0answers
146 views

Snort&Suricata content replacement rule

I have to deal with Surikata IDS and its snort-compatible ruleset. Partially I need it in IPS mode for doing output traffic modifications. For now my "modifications" looks like this: ... pass tcp 192....
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718 views

Understanding remote OS detection using Scapy

I am trying to understand remote OS detection techniques using Scapy. I came across the following article SANS article on Remote OS detection using Scapy and have been trying to follow it. The ...
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0answers
183 views

There's a bunch of TCP connections on my PC to '9gag'

My computer has a bunch of TCP connections to the website 9gag. I used to visit that website a lot a while back but I have not used it in a long time. What's more, I blocked that website from my own ...
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57 views

Does DSR or L3DSR allow for a secret back channel between hosts? How can it be stopped?

This Serverfault question describes how a load balancer can embed data that will be round-tripped back to the originating node. Traditionally DSR can't exceed the boundaries of a broadcast domain. ...
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900 views

Connecting to postgres with SSL

I need help understanding some basics about the postgres database server and SSL. I am developing a Windows desktop application that will connect to a postgres database, in single user mode, with both ...
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1answer
337 views

Could an attacker spoof a whitelisted IP to access the network?

There is a network that is protected with a firewall and only one IP is whitelisted. Assuming the attacker knows the whitelisted IP, what would prevent an attacker from sending traffic via a spoofed ...
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11 views

Any limitaion of clnt_call() in RPC communication?

I have a RPC server and RPC client. Am generating a secure key on client side using TPM1.2 chip. When i run my program for few times everything works fine. But When i run for many times then key is ...
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0answers
332 views

Password-based client login over TCP/TLS

A client connects to a server through an application (not a web browser) with a long-running TCP connection. TLS is used, so the communication is secure. Is there a standard way to implement a ...
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313 views

script for analysis of tcpdump log file

I'm trying to get the following metrics from my tcpdump log file: (1) one-way delay, (2) request/response delay, (3) packet loss, (4) overall transaction duration and (5) delay variation (jitter). ...
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359 views

The simplest way to emulate TCP-IP protocol violation / anomaly attacks

Reading up upon security on web applications I did not found that much info on TCP-IP and in particular HTTP/UDP protocol violation / anomaly attacks. My question: What is the general mechanism of ...
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2answers
311 views

SYN-flood to the localhost Apache server

I've set up the apache server on localhost (127.0.0.1). I've downloaded PackETH to perform a DoS attack. So PackETH wants MAC-HEADER of the destination and source. And I don't know, where to find ...