1.1 – Explain the purposes and uses of ports and protocols. Flashcards
SSH - 22
Secure Shell - Encrypted communication link - tcp/22 - Looks and acts the same as Telnet
DNS - 53
Domain name system - Converts names to IP addresses - udp/53 - These are very critical resources - Usually multiple DNS servers are in production
SMTP 25
Simple mail transfer protocol - Server to server email transfer - tcp/25 - also used to send mail from a device to a mail server - Commonly configured on mobile devices and email clients - Other protocols are used for clients to receive email, IMAP, POP3
SFTP 22
Secure FTP - Uses the SSH file transfer protocol - tcp/22 - provides file system functionality - Resuming interrupted transfers, directory listings, remote file removal
FTP 20, 21
File transfer protocols - tcp/20 (active mode data), tcp21/ (control) - Transfers files between systems - Authenticates with a username and password - Full-featured functionality (list, add, delete, etc.)
TFTP 69
Trivial file transfer protocol - udp 69 - Very simple file transfer application - Reads file and writes file - No authentication - Not used on production systems
Telnet 23
Telecommunication network - tcp/23 - Login to devices remotely - Console access - In-the-clear communication - Not the best choice for productions systems
DHCP 67, 68
Dynamic Host Configuration Protocol - Automated configuration of IP address, subnet mask and other options - udp/67, udp/68 - Requires a DHCP server - Dynamic / pooled: IP addresses are assigned in real-time from a pool - Each system is given a lease - Must renew at set intervals - Reserved: Addresses are assigned by MAC address - Quickly manage addresses from one location
HTTP 80, HTTPS 443
Hypertext Transfer Protocol - Communication in the browser - And by other applications - In the clear or encrypted - Supported by nearly all web servers and clients
SNMP 161
Simple Network Management Protocol - Gather statistics from network devices - udp/161 - v1 – The original: Structured tables, in-the-clear - v2 – A good step ahead: Data type enhancements, bulk transfers - Still in-the-clear - v3 – The new standard: Message integrity, authentication, encryption
RDP 3389
Remote Desktop Protocol - Share a desktop from a remote location over tcp/3389 - Remote Desktop Services on many Windows versions - Can connect to an entire desktop or just an application - Clients for Windows, MacOS, Linux, iPhone, and others
NTP 123
Network Time Protocol - Switches, routers, firewalls, servers, workstations - Every device has its own clock - udp/123 - Synchronizing the clocks becomes critical - Log files, authentication information, outage details - Automatic updates - No flashing 12:00 lights - Flexible - You control how clocks are updated - Very accurate - Accuracy is better than 1 millisecond
SIP 5060, 5061
Session Initiation Protocol - Voice over IP (VoIP) signaling - tcp/5060 and tcp/5061 - Setup and manage VoIP sessions - Call, ring, hang up - Extend voice communication - Video conferencing, instant messaging, file transfer, etc.
SMB 445
Server Message Block - Protocol used by Microsoft Windows - File sharing, printer sharing - Also called CIFS (Common Internet File System) - Direct over tcp/445 (NetBIOS-less) - Direct SMB communication over TCP without the NetBIOS transport
POP3 110
Post office Protocol version 3 - Receive emails from an email server - tcp/110 - Authenticate and transfer - Basic mail transfer functionality
