IT Security Stack Exchange
IT Security Stack Exchange

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.

Transmission Control Protocol (TCP) is a transport layer protocol that provides a connection-oriented data stream service with guaranteed, in-order delivery on top of the underlying packet-oriented, unreliable IP layer. TCP is referred to as a connection-oriented protocol. This is opposed to UDP, which offers a relatively bare-bones unreliable all-or-nothing delivery of discrete packets and referred to as a connection-less protocol.

There is more information at the Wikipedia article on TCP.

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Any Known countermeasures against clock skew fingerprinting?

I know lots of websites that do clock skew fingerprinting using tcp timestamps. I know how to disable timestamps but i want to know techniques that can be used to counter clock skew fingerprinting. I read somewhere that one can spoof this clock skew…
jack
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Why aren't TCP sockets encrypted by default?

I've been wondering this for as long as I've been programming, Why aren't TCP sockets encrypted by default? Everyone always says that using raw sockets is dangerous as all packets sent are susceptible to packet sniffing. So why didn't the original…
Paradoxis
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Can a Cisco ASA 5505 block this DDoS attack?

Since more than a week ago, my dedicated server (located in ovh.com) has been under TCP SYN (I think) attack. OVH don't care about it but this attack is killing my server with a high CPU load (permanent 100% on the top moments). I have the option to…
Dr. House
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Is encryption possible for simplex (one-directional) TCP/IP, and if so, how?

As explained in the TCP/IP Guide, it is possible to configure TCP/IP to operate in simplex mode and this mode is utilized, among other things, in communication from satellites. One consideration with TCP/IP is however that, in itself, it "lacks even…
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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?
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Protect password/authenticating during transit over (insecure) TCP socket for a game

Background I am designing a multi-player game with a single server that handles multiple worlds. Each player logs into the server initially before requesting which world to join. The server has a fixed IP address that is currently the same as the…
Ashley Davies
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Malware / vulnerability that uses or causes malformed IP or TCP Headers

I'm curious if there are any examples of malformed IP or TCP headers (for example, checksums that don't match, reserved bits that aren't zero, or poor header length numbers) used by malware, or that are used in exploits. Examples that (if they were…
Andrew Spott
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Why does my web server receive so many TCP resets from some clients?

I run a web server and log connections that are dropped. Occasionally, I get a burst of TCP RST packets from some of my clients, like this: Feb 11 11:56:29 SRC=1.2.3.4 TTL=57 SPT=38383 DPT=80 WINDOW=0 RST URGP=0 Feb 11 11:56:29 SRC=1.2.3.4 TTL=57…
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Explain the last part of how Mitnick hacked Tsutomu Shimomura with an IP sequence attack

I was reading up on why TCP ISNs need to be randomized, which led me to this write up by Tsutomu Shimomura. I understood how IP address spoofing and predicting the ISN helped the attacker establish a one way connection to the 'x-terminal'. But after…
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Authenticating AD user over TCP socket

I have a server that communicates with clients over a .NET socket. I want the server to authenticate the connection in an SSO kind of style by checking that the current user is in a certain group. The naive way is to send System.Environment.UserName…
Josh Wyant
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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.
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Multiple SSL connections in a single HTTPS web request

I set up Apache2 with SSL and tried to request the default Apache2 web page ("It works!") using https://[IP_ADDRESS]. The Chrome developer tool shows that only one HTTP connection is established, however, from Wireshark's captured packets, there are…
PC Yin
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How is the TLS protected against length field of the header being modified?

I know this question looks very silly, but, it has been bothering me for a while and I am unable to come up with an answer by myself. So, here it goes.. Packets in the TLS protocol consist of a 5 byte header followed by data which is encrypted once…
Jay
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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 that requests originate on an Internet port less…
bers
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Can I blindly trust 127.0.0.1?

On my system (Ubuntu Server 18.04, if that matters) I have two servers. They are behind a Nginx reverse proxy (i.e. accessing service.mywebsite.com internaly proxies the request to 127.0.0.1:servicePort). I have one server which is responsible for…
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