Certified Ethical Hacker CEH CEH-001 Exam Dumps

An Xmas port scan is variant of TCP port scan. This type of scan tries to obtain information about the state of a target port by sending a packet which has multiple TCP flags set to 1 - "lit as an Xmas tree". The flags set for Xmas scan are FIN, URG and PSH. The purpose is to confuse and bypass simple firewalls. Some stateless firewalls only check against security policy those packets which have the SYN flag set (that is, packets that initiate connection according to the standards). Since Xmas scan packets are different, they can pass through these simple systems and reach the target host.

The SOA starts with the format of YYYYMMDDVV where VV is the version.

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).