CEH-001 Exam Dumps : Certified Ethical Hacker (CEH)

ADS (or Alternate Data Streams) is a “feature” in the NTFS file system that makes it possible to hide information in alternate data streams in existing files. The file can have multiple data streams and the data streams are accessed by filename:stream.

Closed UDP ports can return an ICMP type 3 code 3 message. No response can mean the port is open or the packet was silently dropped.

Port 500 is used by IKE (Internet Key Exchange). This is typically used for IPSEC-based VPN software, such as Freeswan, PGPnet, and various vendors of in-a-box VPN solutions such as Cisco. IKE is used to set up the session keys. The actual session is usually sent with ESP (Encapsulated Security Payload) packets, IP protocol 50 (but some in-a-box VPN's such as Cisco are capable of negotiating to send the encrypted tunnel over a UDP channel, which is useful for use across firewalls that block IP protocols other than TCP or UDP).