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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27
votes
4answers
21k views

Is it possible to pass TCP handshake with spoofed IP address?

Little time ago, me and my friends argued if TCP handshake can be passed with a spoofed IP address. Assume I have a web server that allows only certain IP numbers. Can anyone connect that web ...
5
votes
2answers
2k views

Encrypt and Authenticate localhost-traffic?

I have some app-components on the same machine but in different languages which need to communicate. I am using socket communication over localhost to do so. The data transferred is confidential. ...
4
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3answers
10k views

Is it possible to send HTTP packet via spoofed IP?

I have the following PHP code that writes accepted to a file named text.txt only if the IP is equal to 127.0.0.1 (loopback). If the IP doesn't match it writes denied. <?php $file = fopen('text.txt'...
54
votes
11answers
31k views

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 ...
27
votes
4answers
7k views

What security mechanisms are used in BGP and why do they fail?

I just read about Indosat trying to take over the Internet by mistake. I read on a Polish infosec-related website that most of their announced routes failed to propagate, but some of them reached the ...
7
votes
1answer
256 views

Are there any situations when one can only mount a passive MITM?

This came up while discussing Web & insecure HTTP - Using RSA for encrypting passwords on the client side Is there any such situation possible when requesting an HTTP page where an attacker is ...
5
votes
3answers
30k views

FIN Attack- What is this type of attack really?

I just wanted to know what exactly is the FIN attack. I know about the FIN flag that is used to indicated the closing of a connection via TCP. But what exactly is FIN attack?
10
votes
1answer
5k views

TCP “off-path” Attack (CVE-2016-5696)

Today I read that a flaw in a recent TCP specification leads to the injection of malicious content between the two communicating parties. How does the attack vector work? I have also read a post in ...
7
votes
3answers
47k views

Stopping DDOS TCP SYN and UDP flood attacks

I would like to know if it's possible to stop a TCP SYN OR ICMP Flood attacks if these attacks are detected at time. What is the most accurate process to filter these addresses if the only way is to ...
4
votes
4answers
10k views

Is there an alternative to TCP/IP that encrypts end-to-end?

If there was a communication protocol that encrypts at the very low-level, this would solve the problem of wiretapping entirely and for all.
12
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2answers
15k views

Pros and cons of disabling TCP timestamps

So, lynis informs me that I should unset net.ipv4.tcp_timestamps. I know that's a bad thing because an attacker could figure out which updates that require restarting the machine I haven't applied, or ...
11
votes
4answers
4k views

Does HTTPS encryption on a site prevent the NSA from knowing you visited its domain / the URL?

The reason I ask whether HTTPS protects the metadata of your Internet activity from a wiretapping entity on the backbone like the NSA or not, is the following scenario: Say I am browsing the ...
7
votes
3answers
17k views

Why no support for TCP Sockets in JavaScript

I know there are now WebSockets, but what is the issue with providing a socket API to allow interacting with existing protocols? I mean, after all, I can use a hidden flash object to do the same ...
5
votes
1answer
808 views

Security implications for two applications communicating with TCP/IP on localhost

Considering this for the local loopback connection: - It is implemented entirely within the operating system's networking software and passes no packets to any network interface controller. If two ...
4
votes
1answer
3k views

Is it possible to force client use TCP instead UDP for DNS queries?

Assume I am managing a firewall between DNS server and clients. Is there any way to force clients use TCP rather than UDP, so we can prevent DNS spoof types of DDoS attacks?
3
votes
2answers
4k views

Firewall & TCP Traffic

I have a question regarding network firewalls and TCP traffic. When a firewall rule is set to block either inbound traffic, outbound traffic, or both on a port, does that only apply to initial ...
2
votes
2answers
3k views

Identify HTTPS vs Application SSL Traffic

Scenario A: A user points his web browser to https://users.server.com. The website completes the SSL handshake and continues with the HTTP protocol inside SSL. Scenario B: (server-side) Now, let's ...
10
votes
1answer
654 views

Once established, are sockets on localhost secure?

Once a TCP socket has been established on localhost, and a connection made using accept, is it possible for a non-privileged user to intercept or modify bytes sent over this connection, or can this ...
4
votes
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 ...
3
votes
1answer
434 views

In TCP, what happens when two Data packets come in with the same sequential identifier, but different data (spoofed)

I'm trying to verify an answer I posted to a recent question: Client A with real IP has connected ... Now, the attacker machine M sends a [data] packet [with a correct sequential identifier] ...
2
votes
1answer
407 views

Security over multi-streaming such as SCTP

I refer to multi-streaming as the ability to send two or more streams of some unit of data (block, byte streams) in one established association/context. SCTP is an example and the protocol I was ...
2
votes
3answers
2k views

IP Spoofing with real IP when TCP 3-way handshake has been made

In a situation, where the spoofed IP is a real existing remote IP and it is found that the TCP 3-way handshake has been made with a server. The MiTM machine sends the packet with spoofed IP to the ...
-3
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0answers
6k views

Is TCP more secure than UDP? [duplicate]

I am referring to confidentiality not integrity. are there any security features that UDP lack compared to TCP? According to this paragraph While TACACS uses UDP port 49, TACACS+ uses TCP port 49 ...