FTP 20, 21 SSH 22 Telnet 23 SMTP 25 DNS 53 DHCP 67, 68 TFTP 69 HTTP 80 POP3 110 NNTP 119 NTP 123 IMAP4 143 LDAP 389 HTTPS 443 IMAPS 993 RADIUS 1812 RDP 3389 IKE Phase 1 UDP 500 IPsec phase 50
Access control lists (ACLs) perform packet filtering to control the flow of packets through a network. Packet filtering can restrict the access of users and devices to a network, providing a measure of security. Access lists can save network resources by reducing traffic. An access list is sequential in nature and it consists of at …
Firewall is the guard standing between your network and the big bad world outside. In the simplest sense firewall is a filter that filters traffic based on rules and policies. The processes used by a firewall to filter traffic may include the following. Simple packet-filtering techniques Proxy Servers NAT Stateful Inspection Firewalls Transparent Firewall Next-generation …
A zone can be thought of as a logical area where devices with the same trust level reside. A zone can have one more interface but an interface can only belong to one zone. There is a default zone called self zone. Any packet directed to the router or firewall is considered to be entering …
I have a separate post on DNS and if you are new to DNS first read that post before DNS Security Extension (DNSSEC). So We know that DNS resolver makes DNS queries for us but this resolver does not ask any questions regarding the validity of the DNS query it is fetching for you. Any …
Domain Name System (DNS) is a system of converting domain names to designated IP address. As it is difficult for us humans to remember all the IP address of websites we want to visit so DNS helps us to convert the name of the website say google.com to the IP address. In order to understand …
When we talk about layer 2 we are talking about layer 2 of OSI model that is Data Link Layer. In data link layer has one broadcast domain but multiple collision domain. It is important to secure this layer as this will be the first line of defense that a user will connect to. The …
Post Office Protocol version 3 (POP3) is a standard mail protocol used to receive emails from a remote server to a local email client. POP3 allows you to download email messages on your local computer and read them even when you are offline. Note, that when you use POP3 to connect to your email account, messages are …
SMTP is a method to transfer mail from one user to another. SMTP is a push protocol and is used to send the mail whereas POP (post office protocol) or IMAP (internet message access protocol) are used to retrieve those mails at the receiver’s side. SMTP is an application layer protocol. The client who wants …
Internet Communities use to distribute and share news using mailing lists. A mailing list is a list of subscriber’s email addresses. These mailing list would distribute the news by sending the entire news digital article to individual subscribers. This was extremely inefficient way to distribute news as it consumes resources like CPU, Network Bandwidth and …