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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982 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 ...
14
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3answers
513 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 ...
9
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2answers
677 views

Black-box fuzzing a TCP Port running an unknown applicaiton

I'm looking for any guidance around testing a service I've found running on a target server. I'm doing a 'black-box' pen-test and the company is one of those 'I-don't-want-to-tell-you-anything' types ...
7
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4answers
1k views

Is blocking UDP and TCP sufficient to prevent unwanted network activity?

I want to be 100% sure that my machine only connects where and when I want it to. If I use a firewall that blocks all UDP and TCP packets but those that I explicitly allow to pass, can I be 100% sure ...
6
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3answers
1k 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 https web server that allows only admin's IP numbers. Can anyone connect that web ...
6
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3answers
975 views

TCP Sequence Prediction and it's prominence in modern systems/networks

I have a question regarding your experience of TCP Sequence Prediction that I am hoping someone could help with. I am aware of how TCP Sequence Prediction works and how the connection can be hijacked ...
6
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1answer
135 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
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3answers
7k views

How does “traceroute over TCP” work, what are the risks, and how can it be mitigated?

There is a utility called tcptraceroute, and this enhancement called intrace that is used just like a standard traceroute, but it works over TCP. How is the syn flag in TCP used to achieve ...
5
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1answer
453 views

Retrieving client certificate using Tcpdump results in zero length certificate

I am trying to proxy a mobile app (with Fiddler), which sends a client certificate to the server it connects to. I would think that capturing traffic with Tcpdump, retrieving the client certificate ...
4
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1answer
2k views

Why is the server returning 3 SYN + ACK packets during a SYN scan?

When you do a SYN scan against a opened TCP port (not filtered by Firewall), the server normally returns 3 SYN + ACK packets. So, why 3 of that? The target server is a Linux machine if relevanted ...
4
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3answers
904 views

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, ...
3
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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 ...
3
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1answer
65 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 ...
3
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2answers
35 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. ...
3
votes
1answer
185 views

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 ...
2
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3answers
1k 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.
2
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2answers
273 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
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3answers
11k 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 ...
2
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1answer
80 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 ...
2
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1answer
190 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 ...
2
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3answers
591 views

Filtering In Iran

Since many of you already know the Iranian government aggressively uses internet censorship to block sites such as facebook, flicker, bbc, etc. The Iranian people use various methods to bypass ...
2
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2answers
281 views

What are good approaches to modify TLS/SSL trafic in order to make a HTTP bot?

If I wanted to make a bot that plays/issues automatic actions/moves in a online browser game, whose communication is realized over HTTP1/1 and WebSocket (https and wws respectively), all TLS ...
2
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1answer
128 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 ...
2
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1answer
529 views

Expose web service in a secure manner

Requirement I have a web service I need to expose on the DMZ for external communication. The web service communicates directly with a critical database that sits on an internal net. Current ...
2
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2answers
91 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. ...
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4answers
434 views

How a DOS TCP packet different from normal Packet?

a normal tcp packet shown in figure How a TCP packet that causes dos attack different from normal Tcp Packet?
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2answers
852 views

Sending Syslog/SNMP information over the internet using standard UDP port 514

I'm looking into monitoring a Windows VPS by sending Syslog messages to a Synology NAS, which can generate email alerts and such. I also would like to use SNMP to generate health stats, and see trends ...
1
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1answer
209 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 (msg:"HTTP ...
1
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2answers
296 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 ...
1
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2answers
162 views

Securing multiple connections with different protocols all together

I need to secure the communication between an application (runs on any PC and has been designed for Windows) and an external device (runs on UNIX). The application is running on Windows while the ...
1
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1answer
388 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 ...
1
vote
1answer
1k views

Nessus No host data is available for this scan error

I encountered an error in Nessus result. Error: No host data is available for this scan. I want to scan ip 192.16x.x.x at Nessus.I scan this ip with nmap.Only 2 tcp port is open in this ip ...
0
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2answers
143 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 ...
0
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3answers
71 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 ...
0
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1answer
511 views

What triggers a firewall to block a TCP socket?

I was wondering what would cause a firewall to block a TCP Java socket from connecting. What would trigger that?
0
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1answer
96 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
1answer
172 views

Corrupt password being pulled from wireshark data?

Hello everyone, I currently have a pcap file that contains an unencrypted Telnet session, and when I trace the TCP stream the password is in a format like so: pas...ord (please note ...
0
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2answers
81 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 ...
0
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2answers
106 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 ...
0
votes
1answer
130 views

TCP IN connection from another user in my home network. Is it safe?

I'm using Comodo Firewall and I noticed that sometimes I'm getting TCP IN connection from another IP address in my home network (only one router and few wireless users): TCP IN | 192.168.1.50 | ...
0
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1answer
151 views

Is it safe not to encrypt ping packets them?

I am running encrypted communication with ping tacked on after decryption and deserialization is complete. I.e. incoming data -> split into packets -> decrypt -> deserializer -> actual message or ...
0
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0answers
19 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 ...
0
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0answers
22 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 ...
0
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1answer
39 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
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0answers
15 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, ...
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2answers
66 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 ...