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NMAP Scanning Options. EC-Council NMAP  Nmap is the most popular scanning tool used on the Internet.  Cretead by Fyodar (http://www.insecure.org), it.

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Presentation on theme: "NMAP Scanning Options. EC-Council NMAP  Nmap is the most popular scanning tool used on the Internet.  Cretead by Fyodar (http://www.insecure.org), it."— Presentation transcript:

1 NMAP Scanning Options

2 EC-Council NMAP  Nmap is the most popular scanning tool used on the Internet.  Cretead by Fyodar (http://www.insecure.org), it was featured in the Matrix Reloaded movie.

3 EC-Council SYN Scanning  Syn scanning, a technique that is widely across the Internet today.  The syn scan, also called the "half open" scan, is the ability to determine a ports state without making a full connection to the host.  Many systems do not log the attempt, and discard it as a communications error.  You must first learn 3-way handshake to understand the Syn scan.

4 EC-Council TCP Communication Flags  Standard TCP communications are controlled by flags in the TCP packet header.  The flags are as follows: Synchronize - also called "SYN” –Used to initiate a connection between hosts. Acknowledgement - also called "ACK” –Used in establishing a connection between hosts Push - "PSH” –Instructs receiving system to send all buffered data immediately Urgent - "URG” –States that the data contained in the packet should be processed immediately Finish - also called "FIN" –Tells remote system that there will be no more transmissions Reset - also called "RST” –Also used to reset a connection.

5 EC-Council Three Way Handshake Computer AComputer B : syn > : :2342 < syn/ack : : ack > :80 Connection Established  The Computer A ( ) initiates a connection to the server ( ) via a packet with only the SYN flag set.  The server replies with a packet with both the SYN and the ACK flag set.  For the final step, the client responds back the server with a single ACK packet.  If these three steps are completed without complication, then a TCP connection has been established between the client and server.

6 EC-Council Stealth Scan Computer AComputer B : syn > : :2342 < syn/ack : : RST > :80  Client sends a single SYN packet to the server on the appropriate port.  If the port is open then the server responds with a SYN/ACK packet.  If the server responds with an RST packet, then the remote port is in state "closed”  The client sends RST packet to close the initiation before a connection can ever be established.  This scan also known as “half-open” scan.

7 EC-Council Xmas Scan Computer AComputer B Xmas scan directed at open port: : FIN/URG/PSH > : :4031 < NO RESPONSE :23 Xmas scan directed at closed port: : FIN/URG/PSH > : :4031< RST/ACK :23  Note: XMAS scan only works OS system's TCP/IP implementation is developed according to RFC 793  Xmas Scan will not work against any current version of Microsoft Windows.  Xmas scans directed at any Microsoft system will show all ports on the host as being closed.

8 EC-Council FIN Scan Computer AComputer B FIN scan directed at open port: : FIN > : :4031 < NO RESPONSE :23 FIN scan directed at closed port: : FIN : :4031< RST/ACK :23  Note: FIN scan only works OS system's TCP/IP implementation is developed according to RFC 793  FIN Scan will not work against any current version of Microsoft Windows.  FIN scans directed at any Microsoft system will show all ports on the host as being closed.

9 EC-Council NULL Scan Computer AComputer B NULL scan directed at open port: : NO FLAGS SET > : :4031 < NO RESPONSE :23 NULL scan directed at closed port: : NO FLAGS SET : :4031< RST/ACK :23  Note: NULL scan only works OS system's TCP/IP implementation is developed according to RFC 793  NULL Scan will not work against any current version of Microsoft Windows.  NULL scans directed at any Microsoft system will show all ports on the host as being closed.

10 EC-Council IDLE Scan  Almost four years ago, security researcher Antirez posted an innovative new TCP port scanning technique.  Idlescan, as it has become known, allows for completely blind port scanning.  Attackers can actually scan a target without sending a single packet to the target from their own IP address.

11 EC-Council IDLE Scan: Basics  Most network servers listen on TCP ports, such as web servers on port 80 and mail servers on port 25.  A port is considered "open" if an application is listening on the port, otherwise it is closed.  One way to determine whether a port is open is to send a "SYN" (session establishment) packet to the port.  The target machine will send back a "SYN|ACK" (session request acknowledgment) packet if the port is open, and a "RST" (Reset) packet if the port is closed.  A machine which receives an unsolicited SYN|ACK packet will respond with a RST. An unsolicited RST will be ignored.  Every IP packet on the Internet has a "fragment identification" number.  Many operating systems simply increment this number for every packet they send.  So probing for this number can tell an attacker how many packets have been sent since the last probe.

12 EC-Council IDLE Scan: Step 1  Choose a "zombie" and proble for its current IPID number

13 EC-Council IDLE Scan: Step 2  Send forged packet "from" Zombie to target.

14 EC-Council IDLE Scan: Step 3  Probe Zombie IPID again

15 EC-Council Fragmentation scanning  Instead of just sending the probe packet, you break it into a couple of small IP fragments.  You are splitting up the TCP header over several packets to make it harder for packet filters and so forth to detect what you are doing.  The -f switch instructs the specified SYN or FIN scan to use tiny fragmented packets.

16 EC-Council ICMP echo scanning  This isn't really port scanning, since ICMP doesn't have a port abstraction.  But it is sometimes useful to determine what hosts in a network are up by pinging them all.  nmap -P cert.org/ /16

17 EC-Council Scan Options  -sT (TcpConnect)  -sS (SYN scan)  -sF (Fin Scan)  -sX (Xmas Scan)  -sN (Null Scan)  -sP (Ping Scan)  -sU (UDP scans)  -sO (Protocol Scan)  -sI (Idle Scan)  -sA (Ack Scan)  -sW (Window Scan)  -sR (RPC scan)  -sL (List/Dns Scan)

18 EC-Council Ping Detection  -P0 (don’t ping)  -PT (TCP ping)  -PS (SYN ping)  -PI (ICMP ping)  -PB (= PT + PI)  -PP (ICMP timestamp)  -PM (ICMP netmask)

19 EC-Council Output Format  -oN(ormal)  -oX(ml)  -oG(repable)  -oA(ll)

20 EC-Council Timing  -T Paranoid – serial scan & 300 sec wait  -T Sneaky - serialize scans & 15 sec wait  -T Polite - serialize scans & 0.4 sec wait  -T Normal – parallel scan  -T Aggressive- parallel scan & 300 sec timeout & 1.25 sec/probe  -T Insane - parallel scan & 75 sec timeout & 0.3 sec/probe  --host_timeout --max_rtt_timeout (default )  --min_rtt_timeout --initial_rtt_timeout (default – 6000)  --max_parallelism --scan_delay (between probes)

21 EC-Council  --resume (scan) --append_output  -iL -p  -F (Fast scan mode) -D  -S -e  -g --data_length  --randomize_hosts -O (OS fingerprinting) -I (dent- scan)  -f (fragmentation) -v (verbose) -h (help)  -n (no reverse lookup) -R (do reverse lookup)  -r (dont randomize port scan) -b (FTP bounce)


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