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Scanning

Scanning. CS391. Overview. The TCP protocol: quick overview Scanning Fingerprinting OS Detection. The TCP Protocol. Transmission Control Protocol (the transport layer of the Internet). Connection oriented. Reliable. Point-to-point Flow control. application transport network

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Scanning

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  1. Scanning CS391

  2. Overview • The TCP protocol: quick overview • Scanning • Fingerprinting • OS Detection.

  3. The TCP Protocol • Transmission Control Protocol (the transport layer of the Internet). • Connection oriented. • Reliable. • Point-to-point • Flow control

  4. application transport network data link physical application transport network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical logical end-end transport TCP • Overview

  5. TCP Header

  6. Flags

  7. Connection Establsihment

  8. Some Well Known Ports

  9. Scanning • Objectives: • Determining if the system is alive. • Determining which services are running or listening. • Detecting the operating system.

  10. System Alive? • The major technique is to use ping sweeps or similar techniques. • Tools such as fping or supersacn may be used.

  11. What processes are running or listening? • Identify both TCP and UDP services running on the target system. • Identify applications or versions of services running.

  12. Scan types • TCP connection. • TCP SYN scan. • TCP FIN scan. • TCP NULL scan. • TCP ACK scans.

  13. tools • Netcat. • Strobe. • Nmap. • Superscan

  14. Detecting OS • The major technique is known as stack fingerprinting. • The general idea is to send packets to the target and analyze the reply. • Operating systems differ in their implementation of TCP/IP protocol stack.

  15. Examples • FIN probe: OS’s differ in their response to a FIN packet. • TCP initial window size: unique for some implementations.

  16. Tools • NMAP

  17. inetnum: 212.71.32.0 - 212.71.45.255 netname: NESMA descr: National Engineering Services descr: and Marketing Company Ltd. (NESMA) country: SA admin-c: NAR12-RIPE tech-c: NTR2-RIPE status: ASSIGNED PA mnt-by: NESMA-MNT source: RIPE # Filtered person: NESMA ADMIN RIPE address: National Engineering Services and Marketing Company Ltd. address: NESMA - Internet Services address: P.O. Box 300940, Riyadh 11372 - KSA phone: +9661 465 6767 fax-no: +9661 462 6034 e-mail: NOC@NESMA.NET.SA nic-hdl: NAR12-RIPE source: RIPE # Filtered person: NESMA Tech RIPE address: National Engineering Services and Marketing Company Ltd. address: NESMA - Internet Services address: P.O. Box 300940, Riyadh 11372 - KSA phone: +9661 465 6767 fax-no: +9661 462 6034 e-mail: NOC@NESMA.NET.SA nic-hdl: NTR2-RIPE source: RIPE # Filtered % Information related to '212.71.32.0/19AS24731' route: 212.71.32.0/19 descr: National Engineering Services and Marketing Company Ltd. origin: AS24731 mnt-by: NESMA-MNT source: RIPE # Filtered

  18. Banner Grabbing • $ nc 202.41.76.251 80 • HEAD / HTTP/1.0 • HTTP/1.1 200 OK • Date: Mon, 16 Jun 2003 02:53:29 GMT • Server: Apache/1.3.3 (Unix) (Red Hat/Linux) • Last-Modified: Wed, 07 Oct 1998 11:18:14 GMT • ETag: "1813-49b-361b4df6" • Accept-Ranges: bytes • Content-Length: 1179 • Connection: close • Content-Type: text/html • $

  19. Banner Grabbing • HTTP/1.1 200 OK • Server: Microsoft-IIS/5.0 • Expires: Tue, 17 Jun 2003 01:41:33 GMT • Date: Mon, 16 Jun 2003 01:41:33 GMT • Content-Type: text/html • Accept-Ranges: bytes • Last-Modified: Wed, 28 May 2003 15:32:21 GMT • ETag: "b0aac0542e25c31:89d" • Content-Length: 7369

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