Does an attacker need to guess or brute-force a password for TCP spoofing?

From my understanding, TCP spoofing can be carried out if the attacker can correctly guess the sequence numbers from the response packets (to mimic the real client). The attacker may even obtain this sequence of numbers via sniffing. Furthermore, a trusted connection must already exist between the target client and the server in order for the attacker to intercept/spoof

However, I was a bit unclear as to whether the attacker would need to gain initial access to the system or network (by guessing or brute-forcing their password). In order to send the sequence numbers from response packets to the server, does the attacker need to have access to it? I am not sure whether this attacker can just send the SYN packets to the server without any access to the system/network. My concept of these things is a bit blurry right now and I would greatly appreciate some advice.

Thank you!

Does brute-force time depend on the length of a password only?

Length is certainly a factor, but you’ve hit on an underlying fact that most people miss: even a 30 char password is weak if it is guessable.

The concept that is important is “entropy”. It’s not just length or even the types of characters used, but how the password is chosen. The randomness, the character types used, and the length all contribute to password strength.

But if everyone uses the password: Look at me!! I'm a really long password!! (that’s 41 characters), then it’s not really strong, is it?

You’ve asked about brute-forcing, and there are different types. Trying every password length, character by character starting from abcd... is a sure way to eventually get the password, but it might take billions of years. But that’s not the only type.

Dictionaries are used, common patterns are tried, known passwords are checked.

So, yes, if a 30-char password with dictionary words is used, and those words are randomly chosen, then that’s a strong password.

!@#$#%$^%$ will be guessed relatively quickly because that’s a common keyboard pattern.

brute force attacks – Block bruteforce attempts with nginx & cloudflare without rate limiting

So I discovered servers trying to bruteforce my API so I want to block them…but my specific scenario made it difficult to work with common solutions found on the internet.

1] I don't want to just rate limit, if any IP attempts to authenticate with the API and fail more than X times in ~6 hours I want to block them. No answers anymore at all. Not even 429 replies

2] I'm using cloudflare, so I need to use the CF IP header

3] I can't block the traffic based on iptables or similar solutions, since the only IPs that talk to my server are cloudflare IPs

4] The API generates nginx errors if the authentication fails with `2: no such file or directory` if that helps with something

Given my scenario, what are the possible solutions?

tls – Bruteforce https publication using a single tcp connection

So I tried to apply brute force to my server using thc-hydra https-post-form, but it floods the server very quickly and the requests begin to expire.

However, if I go through the browser where the server uses and accepts the HTTP Connection: Keep Alive header, I can make many requests in quick succession without flooding the server.

Is there a tool like Hydra that can be used to send many https publication requests using a single TCP connection?

Pathetic support in KnownHost for BruteForce attacks

Hello raj

I apologize for feeling that our support is pathetic. By chance I see your ticket open and I will gladly investigate further.

Keep in mind that one thing I do see is that you have CloudFlare in front of most of your websites, this will limit what the server can do in some circumstances since it will not be as simple as the basic firewall blocks, but you should trust CloudFlare themselves to divert part of the traffic.

Anyway, I will answer more on your ticket and we will see what is happening with your server.

java: how to make appropriate changes to the bruteForce method to decrypt password hashes

I want to break the password hash.
These are my data that I want to show the username and passwords. Please ignore if my edition is incorrect. I am new to the stack flow.

Thanks in advance.

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This is my code

import java.io.FileReader;
import java.io.Console; // for hidden password entry
import java.util.Scanner; // for clear text entry
import java.security.MessageDigest; // for MD5
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.SecretKey;
import javax.xml.bind.annotation.adapters.HexBinaryAdapter; // for the hexadecimal byte format[]
import com.opencsv.CSVReader; // library to read CSV files (jar in the folder + libs)

public class LabSecurity {
final static private cover[] characters = {& # 39; a & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39; e & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;,
& # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39; p & # 39 ;, # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39 ;, & # 39; v & # 39 ;, & # 39; w & # 39;, & # 39; x & # 39;, & # 39; and & # 39 ;, & # 39; z & # 39;};

static final private int HASH_ITERS = 10000;
private static end int SALT_LENGTH = 32;
static final private int HASH_LENGTH = 512;

Private boolean found;
private rope match;

Private MessageDigest md5; // implement the algorithm
private byte[] byteRepresentation;
private byte[] Hash;
Private string StrHexHash;
Private HexBinaryAdapter hba; // used to convert bytes[] Chain

/ **
* Constructor for LabSecurity class objects.
* /
public laboratory safety () {
try {
md5 = MessageDigest.getInstance ("MD5");
hba = new HexBinaryAdapter ();
} catch (NoSuchAlgorithmException nsae) {
}
}

public empty tryMD5 () {
try {
String Str;
do {
System.out.println ("Enter a string to generate its MD5 hash (press Enter to exit)");
Terminal ScannerInput = new Scanner (System.in);
str = terminalInput.nextLine ();
// Comment the 2 previous lines and eliminate the comment of the following 2 lines to hide the password entry (it will generate an exception in the IDE)
// Console console = System.console ();
// str = new String (console.readPassword ("Please enter your password:"));
if (! str.equals ("")) {
System.out.println (encodeMD5 (str));
}
} while (! str.equals (""));
} catch (exception e) {
}

}

The private string encodeMD5 (final entry of the string) throws the exception {
// convert the string to byte[] using UFT-8 character encoding
byteRepresentation = input.getBytes ("UTF-8");
// generate the hash
hash = md5.digest (byteRepresentation);
// The Marshal method of HexBinaryAdapter converts the byte[] Representation of hexadeciaml character strings.
strHexHash = hba.marshal (hash);
returns strHexHash;
}

public void bruteForce (final entry of String) {
try {
CSVReader reader = new CSVReader (new FileReader (entry));
Rope[] next line;
reader.readNext (); // omit first line containing headers
System.out.println ("Brute force");
while ((nextLine = reader.readNext ())! = null) {
// next line[] It is a matrix of values ​​of the line.
System.out.print (nextLine[0] + "" + nextLine[1] + "");
found = false;
// TODO call bruteForceRecursive
Chain password = "not found";
if found) {
password = match;
}
System.out.println (password);
}
} catch (exception e) {
}
}

/ **
* Recursively explore all passwords shorter or equal to the parameter ,
* composed of characters from the  class variable
* to find the password that has the same MD5 hash as parameter .
* The  The global variable must be initialized to false before calling the method.
* The results are stored in the  Y  global variables.
* 

* bruteForceRecursive (10, 0, "", ) will try passwords * of 10 or less characters until you find one that yields to or * all passwords have been tried without success * / private void bruteForceRecursive (final int length, final int position, String baseString Final String, final String hash) throw Exception { // test if baseString + any of the potential characters is the hash for (int i = 0; i <characters.length &! found; i ++) { String attempt = baseString + characters[i]; found = hash.equals (encodeMD5 (intent)); if found) { match = try; } else { // if the last attempt was unsuccessful // and the maximum length of the password is not reached // then recursively calls the method to test a longer password yes (position <length - 1) { bruteForceRecursive (length, position + 1, intent, hash); } } } } Public chain hashHash (string password) { String result = ""; return result } private byte[] hashPassword (final char[] password, final byte[] salt, int final iterations, final int keyLength) { try { SecretKeyFactory skf = SecretKeyFactory.getInstance ("PBKDF2WithHmacSHA512"); PBEKeySpec spec = new PBEKeySpec (password, salt, iterations, keyLength); SecretKey key = skf.generateSecret (spec); byte[] res = key.getEncoded (); come back; } catch (NoSuchAlgorithmException | InvalidKeySpecException e) { launch new RuntimeException (e); } } }