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

learn more… | top users | synonyms

2
votes
1answer
28 views

things to do to ensure that data is secured on my virtual server [on hold]

I'm not much of an administrator but I'm maintaining a virtual server with Ubuntu OS where my website is hosted. I often connect to it using ssh, ftp and whatever the protocol MySQL uses. As my ...
1
vote
0answers
22 views

What is the primary function of the transport layer in the Internet protocol networking code [migrated]

I am not sure if I have answered this question right, so would appreciate it if someone could correct me. The question is: What is the primary function of the transport layer in the Internet protocol ...
7
votes
2answers
112 views

Why do ISPs allow faked source IP addresses?

Ok so apparently you can specify a source IP when doing a SYN request or something. Besides just asking why in the world that would even be allowed, I will move past that because I want to understand ...
5
votes
3answers
104 views

Can you sniff traffic to ip address from outside of your network?

I am not sure what it is called or even if it is possible but here is the scenario I am curious about: I login to a site that does not use SSL/TLS to do some work (unfortunately I must use this site ...
1
vote
0answers
53 views

Random SYN_SENT connections to Amazon EC2?

I have looked around but couldn't find anyone else with this issue. On my console (standard asus i7 laptop) running Ubuntu 14.04 LTS - I noticed in tcptrack that there are a lot of connections being ...
1
vote
3answers
139 views

How to make a secure communication between two applications on the same system

I'm writing a software which is divided into two separate stand-alone pieces, one is a service like application that handles all the logics, the other one is a GUI application that just works as a ...
1
vote
1answer
52 views

UDP-Only Linux Dedicated Server?

I am running my own small UDP linux service on a dedicated server. my service responds to single-package requests with single-package responses. I don't want this server to do anything else. I ...
4
votes
1answer
129 views

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 ...
2
votes
3answers
154 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?
4
votes
1answer
116 views

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 ...
1
vote
0answers
339 views

Security risk of opening port 111 (rpcbind)?

As far as I understood rpcbind is used for listing active services, and telling the requesting client where to send the RPC request. If a host listens on port 111, one can use rpcinfo to get program ...
1
vote
2answers
131 views

In detail, how does SSL offloading/acceleration/termination work?

What is the in-depth working mechanism of SSL offloading/termination? I could not find literature that would dive deep enough into the subject. Assume the following example, where a intends to ...
11
votes
4answers
3k 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 ...
4
votes
1answer
81 views

Do concurrent connections to an HTTPS website perform separate SSL handshakes?

I know that most browsers nowadays support around 6 concurrent TCP sessions per hostname, to perform multiple requests at the same time. For sites which utilise SSL, is there a separate handshake ...
1
vote
2answers
64 views

Is it secure to split information into multiple packets?

I just stumbled upon this SO question. I was wondering if it would be still secure to split the encrypted packet into multiple packets, which are then transferred over the wire separately. Could ...
1
vote
0answers
103 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 ...
-2
votes
2answers
47 views

TLS - Are signatures still needed?

The story: I'm currently writing a web service that allows for communications to be made remotely via TCP/IP. I first thought about signing each packet using HMAC-SHA1 with a password, appending the ...
5
votes
2answers
1k views

How could a SYN flood affect a home router

I was curious how a DoS attack would affect a home router. In particular, I'm interested in how a SYN flood would affect a home router. The reason I'm interested is due to a Cisco document I read. ...
2
votes
1answer
74 views

Downloading operating systems vulnerable to TCP amplification

I am doing a security research project on TCP amplification, and was looking to download vulnerable OS's for testing. From what I have researched mostly ancient linux kernels (2.0.x and below) and ...
0
votes
1answer
120 views

Are these port secured on my AP?

I'm doing a project for my high-school and I'm trying to get the best security for my network. I've made almost everything in my access-point configuration and I have only 3 tcp/ports open on my AP: ...
6
votes
2answers
343 views

How can I explain to the client that rfc2385 TCP MD5 Checksums can't be turned on for linux webservers?

I've had a long running conversation with a client where they perform a Rapid7 security scan which then warns about TCP MD5 checksums missing on port 80. This is what I think I know: RFC 2385 was ...
1
vote
1answer
138 views

Strange TCP traffic on Mac OS X from 'rdmd'

I noticed some curious traffic today on my MBP after running lsof. It seemed that a process called rdmd had begun 3 TCP sessions: rdmd 85842 0 9u IPv4 0xca0e547f0a118fdb 0t0 TCP ...
2
votes
2answers
159 views

Protecting against GCHQ port scans: How does TCP stealth work?

Today I read the first time about a draft of TCP Stealth which should serve as a protection against GCHQ and NSA vulnerability scanning(Source: https://en.wikipedia.org/wiki/TCP_Stealth): The ...
-4
votes
2answers
739 views

Is TCP more secure than UDP? [closed]

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 ...
1
vote
3answers
198 views

Capture query to MySQL in Server

I want to capture queries to MySQL from my web-application on my Linux-based Server. MySQL port is 3306 and my web-application in on port 8181. So I started using tcpdump as follow: # tcpdump -x ...
1
vote
0answers
101 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 ...
0
votes
2answers
224 views

Does Nmap requires a closed TCP port to do OS fingerprinting?

I was checking the security of a server by running Nmap. Last time it gives me the following results, indicating that OS could not be fingerprinted: PORT STATE SERVICE VERSION 21/tcp ...
0
votes
0answers
149 views

OSSEC, what is it telling me about port changes?

I've been diving into OSSEC for the last couple of months, but I feel unclear on one of it's alerts. I've provided the alert below. The main difference I see in previous output and current output is ...
2
votes
2answers
122 views

Does NTP leak local system time?

As I understand the paper An Improved Clock-skew Measurement Technique for Revealing Hidden Services (6/23 = pdf page 3), it implies that a NTP client leaks the system's local time because of TCP ...
0
votes
0answers
119 views

How to simulate an UDP / TCP / Multiple Ports via Honeyd daemon?

I am using honeyd daemon to simulate TCP port on a Linux Ubuntu machine using honeyd.conf file which was configured to do so with the following script :- 1 create default 2 set default personality ...
3
votes
1answer
98 views

Is it possible to find out what a remote user is trying to do connecting to a closed port?

From my iptables log, I can observe a particular remote IP address trying to connect to my server from port 80 to a private port number: Jul 09 01:24:41 example.com kernel: IPTABLES: IN=eth1 ...
0
votes
0answers
51 views

Is it possible to covertly tunnel data using L3DSR? (or any other TCP or IP layer hack)

I asked this question on ServerFault regarding how a Netscaler embeds low level data in a TCP packet, round-trips it, and then uses that data to loadbalance the user. Similar to DNS Tunneling, I ...
3
votes
2answers
114 views

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. ...
0
votes
1answer
139 views

Wireshark: could “Follow TCP Stream” yield an empty window? or is it a bug?

I am capturing a pop3 netcat connection (port 110) using Wireshark, on Debian linux (Kali). After filtering packets with (tcp.port eq 110) I get few packets but once I R.Click on any and click "Follow ...
0
votes
1answer
198 views

Firewall hole punching [closed]

I'm interested in doing my thesis on Firewall hole punching. Hole Punching: A way to exploit NAT to open a connection TCP or UDP between a Client and a Server. What I'm looking for is a reason this ...
0
votes
0answers
37 views

How to route RST injections

Lots of security appliances and software support RST injection. Plenty of material exists on the algorithmics of the RST packet(s) (making them fit the context of the targeted TCP connection, ...
0
votes
2answers
256 views

How does the TCP/IP lack security? [closed]

I already know that some concerns of lack of security in TCP/IP are that TCP/IP does not support strong authentication of packets and no encryption of packets. What other weaknesses are there in the ...
3
votes
1answer
520 views

What is DDOS TCP KILL?

I've recently been introduced to Kali Linux's webkiller tool, located in the websploit category. It works on the concept of Tcpkill. I don't understand how the DoS attack with Tcpkill works. Can ...
3
votes
2answers
1k views

Is my ISP doing a port scan on my computer?

I have been logging incoming connections with iptables for a while and I have been observing the following popping up periodically: 11:45:10 my.com kernel: IPTABLES: SRC=220.255.XX.XXY ...
2
votes
2answers
136 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. ...
0
votes
2answers
159 views

Security concerns with TCP holding onto out-of-order packets?

Consider the following... Alice and Bob are communicating over TCP. Currently, the next expected TCP sequence number is 1000. Charlie, pretending to be Alice, sends a spoofed TCP packet to Bob with ...
14
votes
3answers
906 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 reach the ...
23
votes
1answer
1k views

Does TCP/IP protocol offer a reliable way of determining who the actual sender was?

So I'm just poking around the TCP/IP protocol using a Ruby library called PacketFu, and it seems to me that in each packet, it is possible to set all of the following Source IP Destination IP Source ...
0
votes
3answers
266 views

How source port field in firewall rule is used

Some firewalls (like the first figure in 13.1.4 in http://doc.m0n0.ch/handbook/examples.html) allow user to specify source port in a firewall rules. But in a TCP connection, the source port is ...
2
votes
1answer
240 views

IPSec sequence number

I was going through a study of IPsec and I found that there are redundant sequence numbers: one in the AH or ESP header, and the other is in the TCP header for a communication. Is it not an ...
0
votes
2answers
186 views

Proxy traffic via MITM script

I want to log and modify outbound traffic on a Linux machine. I currently have one program that sends requests out to the internet, I would like to process these requests and their responses via ...
-2
votes
2answers
131 views

Trojan TCP and UDP ports removal solution?

After a nmap scan on my local host on my Windows 7 machine results showed a vast list of open ports. I'm using Windows Firewall. This machine was given to me by a friend. I've had my network crash ...
1
vote
1answer
643 views

Block Packets in snort

In rules Configuration of snort , this is allowed: alert tcp any any -> any any (msg:"HTTP Connection"; react:block;) however when I write this is allowed: alert icmp any any -> any any ...
3
votes
1answer
722 views

How are ACK storms created and what's a good mitigation strategy for them?

The context is network based load balancers. It would be nice if someone could explain how TCP ACK storms are generated in real life and practical mitigation strategies for them. Edit: Clarification ...
1
vote
1answer
955 views

Reverse TCP connection from exploited SearchIndexer.exe failing

I'm working on a tool that exploits SearchIndexer.exe on Windows 7 x86 and connects back to a metasploit multi/handler, using standard metasploit reverse TCP stagers. The exploit seems to function as ...