A part of the DNS service is that it uses UDP, and Azure Firewall uses SNAT for address translation from every internal source, resulting in every UDP request from one IP to an external provider (8.8.8.8, 8.8.4.4, 1.1.1.1 etc.) will use one port out of the 65.000 available in the TCP protocol for that unique destination.
SG Security Scan. About the SG Security Scan The SG Security Audit is a comprehensive remote port scanner that audits a number of commonly used ports on your system in order to detect potenital security vulnerabilities. Many of those ports are used by servers, sharing services, trojans/backdoors, worms, as well as crackers trying to break into your system, or obtain information about it. Don’t Forget To Leverage The Benefits of RD Gateway On Feb 12, 2015 TCP/UDP port 0 and TCP/UDP port 1 - Cisco Community permit udp host x.x.x.x host x.x.x.x. gt 1 log. Maybe it is security recommended that port 0 and 1 are blocked. I saw in the nessus link, that port 0 can be abused for DoS. Some other reasons when these ports can be abused? TCP/IP Network Security(OSI Model) To properly program firewall filters, the security administrator must have a deep understanding and knowledge of the IP and TCP/UDP layers of TCP/IP. An understanding of TCP/UDP ports is vital. Experienced hackers understand how to exploit network operations through the TCP/IP protocol stack.
By design, UDP is a connection-less protocol that does not validate source Internet Protocol (IP) addresses. Unless the application-layer protocol uses countermeasures such as session initiation in Voice over Internet Protocol, an attacker can easily forge the IP packet datagram (a basic transfer unit associated with a packet-switched network) to include an arbitrary source IP address.
In UDP, the client does not form a connection with the server like in TCP and instead just sends a datagram. Similarly, the server need not accept a connection and just waits for datagrams to arrive. Datagrams upon arrival contain the address of sender which the server uses to send data to the correct client. UDP Service Enumeration with the Passive Vulnerability Scanner. Another interesting way of identifying UDP client and server applicants in use is to simply sniff the network traffic. Tenable's Passive Vulnerability Scanner identifies a wide variety of UDP based protocols and associated vulnerabilities in both the clients and servers. This has What is User Datagram Protocol (UDP/IP)? UDP is a communication protocol used across the Internet for especially time-sensitive transmissions such as video playback or DNS lookups. It speeds up communications by not requiring what’s known as a “handshake”, allowing data to be transferred before the receiving party agrees to the communication.
UDP Reflection Attacks and Security Implications. UDP port scans should not be ignored by testers as they can leave an organization vulnerable to a number of different attacks, these include exploitable services that can lead to remote execution, or commonly UDP reflection attacks against services such as NTP and DNS.
TCP/IP Network Security(OSI Model) To properly program firewall filters, the security administrator must have a deep understanding and knowledge of the IP and TCP/UDP layers of TCP/IP. An understanding of TCP/UDP ports is vital. Experienced hackers understand how to exploit network operations through the TCP/IP protocol stack. UDP-Based Amplification Attacks | CISA By design, UDP is a connection-less protocol that does not validate source Internet Protocol (IP) addresses. Unless the application-layer protocol uses countermeasures such as session initiation in Voice over Internet Protocol, an attacker can easily forge the IP packet datagram (a basic transfer unit associated with a packet-switched network) to include an arbitrary source IP address.