· 5 years ago · Jan 16, 2020, 04:00 AM
1Linux ubunut
2 1)iptables
31.show policies of iptables
4 sudo iptables -L
52.allowing incoming traffic on specific port
6 sudo iptables -A INPUT -p tcp --dport ssh -j ACCEPT
7 sudo iptables -L
8
93.allowing to established sessions
10 sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
11 sudo iptables -L
12
134. set default policies for iptables filter tables/using -p flag
14 sudo iptables -t filter -p OUTPUT DROP
15 sudo iptables -L
16 sudo iptables -t filter -P INPUT DROP
17 sudo iptables -L
18disable firewall fpr temporaray basis
19 sudo iptables -t filter -P OUTPUT ACCEPT
20 sudo iptables -t filter -P INPUT ACCEPT
21
225. Allow machine to send only http req&ssh req
23 sudo iptables -A INPUT -p tcp -i eth0 --dport 80
24 sudo iptables -L
25 sudo iptables -A INPUT -p tcp -i eth0 --dport 22
26 sudo iptables -L
27
286.allow connections to port 20 21
29 sudo iptables -A INPUT -p tcp -i eth0 --dport 20
30 sudo iptables -L
31 sudo iptables -A INPUT -p tcp -i eth0 --dport 21
32 sudo iptables -L
33
348. block traffic
35 sudo iptables -A INPUT -j DROP
36 sudo iptables -L
37
387.Allow all incoming web traffic/LAN
39 sudo iptables -A OUTPUT -j ACCEPT -p all -d 192.168.65.22(own pc ip) -o eth0
40 sudo iptables -L
41 sudo iptables -A INPUT -j ACCEPT -p all -s 192.168.65.22(own pc ip) -i eth0
42 sudo iptables -L
43
449.Demonstarte logging
45 sudo iptables -N LOGGING
46 sudo iptables -L
47 sudo iptables -A INPUT -j LOGGING
48 sudo iptables -L
49
50to log packets with prefix
51 sudo iptables -A LOGGING -m limit --limit 5/min -j LOG --log -prefix "iptables denied:" --log -level7
52 sudo iptables -L
53
5410.Edit iptables
55 sudo iptables -A INPUT -i 10 -j ACCEPT
56save ip config
57 sudo su
58 iptables -save>filename.txt
59
60
612) Buffer/String ATtack
62inside ubunut
63
64#include <stdio.h>
65#include <string.h>
66
67int main(void)
68{
69char buff[15];
70int pass = 0;
71printf("\n Enter the password : \n");
72gets(buff);
73if(strcmp(buff, "thegeekstuff"))
74{
75printf ("\n Wrong Password \n");
76}
77else
78{
79printf ("\n Correct Password \n");
80pass = 1;
81}
82if(pass)
83{
84/* Now Give root or admin rights to user*/
85printf ("\n Root privileges given to the user \n");
86}
87return 0;
88}
89
90
91.c save
92terminal:
93gcc filename.c -o filename
94./filename
95
96
97TCP/IP
98
99import java.io.*;
100import java.net.*;
101
102class TCPSE
103{
104
105 public static void main(String argv[]) throws Exception
106 {
107 String fromclient;
108 String toclient;
109
110 ServerSocket Server = new ServerSocket (5000);
111
112 System.out.println ("TCPServer Waiting for client on port 5000");
113
114 while(true)
115 {
116 Socket connected = Server.accept();
117
118 System.out.println( " THE CLIENT"+" "+connected.getInetAddress() +":"+connected.getPort()+" IS CONNECTED ");
119
120 BufferedReaderinFromUser = newBufferedReader(new InputStreamReader(System.in));
121
122 BufferedReaderinFromClient = newBufferedReader(new InputStreamReader (connected.getInputStream()));
123
124 PrintWriteroutToClient = newPrintWriter(connected.getOutputStream(),true);
125
126 while ( true )
127 {
128
129 System.out.println("SEND(Type Q or q to Quit):");
130 toclient = inFromUser.readLine();
131
132 if ( toclient.equals ("q") || toclient.equals("Q") )
133 {
134 outToClient.println(toclient);
135 connected.close();
136 break;
137 }
138 else
139 {
140 outToClient.println(toclient);
141 }
142
143 fromclient = inFromClient.readLine();
144
145 if ( fromclient.equals("q") || fromclient.equals("Q") )
146 {
147 connected.close();
148 break;
149 }else
150 {
151 System.out.println( "RECIEVED:" + fromclient );
152 }
153 }
154 }
155 }
156}
157
158import java.io.*;
159import java.net.*;
160
161class TCPCL
162{
163 public static void main(String argv[]) throws Exception
164 {
165 String FromServer;
166 String ToServer;
167
168 Socket clientSocket = new Socket("localhost", 5000);
169
170 BufferedReaderinFromUser = newBufferedReader(new InputStreamReader(System.in));
171
172 PrintWriteroutToServer = new PrintWriter(clientSocket.getOutputStream(),true);
173
174 BufferedReaderinFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
175
176 while (true)
177 {
178
179 FromServer = inFromServer.readLine();
180
181 if ( FromServer.equals("q") || FromServer.equals("Q"))
182 {
183 clientSocket.close();
184 break;
185 }
186
187 else
188
189 {
190 System.out.println("RECIEVED:" + FromServer);
191 System.out.println("SEND(Type Q or q to Quit):");
192
193 ToServer = inFromUser.readLine();
194
195 if (ToServer.equals("Q") || ToServer.equals("q"))
196 {
197 outToServer.println (ToServer) ;
198 clientSocket.close();
199 break;
200 }
201
202 else
203 {
204 outToServer.println(ToServer);
205 }
206 }
207 }
208 }
209}
210
211
212JAVA FILE
213TCPSE
214 TCPCL
215javac filename.c
216java filename
217
218BLOWFISH
219
220import javax.crypto.Cipher;
221import javax.crypto.KeyGenerator;
222import javax.crypto.SecretKey;
223import javax.swing.JOptionPane;
224
225public class Blowfish
226{
227 public static void main(String[] args) throws Exception
228 {
229 KeyGenerator keygen = KeyGenerator.getInstance("Blowfish");
230
231 // create a key
232
233
234 SecretKey secretkey = keygen.generateKey();
235
236 Cipher cip = Cipher.getInstance("Blowfish");
237
238
239 // initialise cipher to with secret key
240
241 cip.init(Cipher.ENCRYPT_MODE, secretkey);
242
243 String inputText = JOptionPane.showInputDialog(" Give Input: ");
244
245 byte[] encrypted = cip.doFinal(inputText.getBytes());
246
247 cip.init(Cipher.DECRYPT_MODE, secretkey);
248
249 byte[] decrypted = cip.doFinal(encrypted);
250
251 JOptionPane.showMessageDialog(JOptionPane.getRootFrame(), "encrypted : " + new String(encrypted) + "\n" + "decrypted : " + new String(decrypted));
252
253 System.exit(0);
254 }
255}
256javac filename.c
257java filename