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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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19 votes
3 answers
13k 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 ...
NULLZ's user avatar
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6 votes
1 answer
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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 ...
TheDarkKnight's user avatar
3 votes
1 answer
5k 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 ...
Riri's user avatar
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1 answer
283 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 | 192....
isitsafe's user avatar
0 votes
1 answer
269 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 ...
Coeus's user avatar
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2 votes
2 answers
5k 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 ...
Louis Somers's user avatar
0 votes
1 answer
2k views

Is it safe not to encrypt ping packets?

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 ...
Nuoji's user avatar
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5 votes
1 answer
5k 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 ...
Spyros's user avatar
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29 votes
3 answers
65k 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 traceroute ...
makerofthings7's user avatar
4 votes
4 answers
12k 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.
rubo77's user avatar
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3 votes
2 answers
6k 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 ...
QAH's user avatar
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37 votes
4 answers
34k 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 addresses. Can anyone connect that web ...
ibrahim's user avatar
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1 vote
1 answer
7k 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?
user151324's user avatar
4 votes
3 answers
5k 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, ...
PC Yin's user avatar
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3 votes
3 answers
2k 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 ...
mr X's user avatar
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4 votes
1 answer
1k 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 ...
Jay's user avatar
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7 votes
1 answer
391 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 ...
Manishearth's user avatar
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7 votes
1 answer
10k 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 ...
daisy's user avatar
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11 votes
3 answers
17k 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 ...
yonetpkbji's user avatar
7 votes
3 answers
50k 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 ...
maya-bf's user avatar
  • 73
0 votes
5 answers
4k 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?
open source guy's user avatar

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