Networking concepts - 23% Flashcards
(25 cards)
SSH - Secure Shell
- Encrypted communication link - tcp/22
* Looks and acts the same as Telnet
DNS - Domain Name System
- Converts names to IP addresses - udp/53
* www.professormesser.com = 162.159.246.164
SMTP - 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 - Secure FTP
• Uses the SSH File Transfer Protocol - tcp/22
• Provides file system functionality
• Resuming interrupted transfers, directory listings,
remote file removal
FTP – File Transfer Protocol
- tcp/20 (active mode data), tcp/21 (control)
- Transfers files between systems
- Authenticates with a username and password
- Full-featured functionality (list, add, delete, etc.)
TFTP – Trivial File Transfer Protocol
- udp/69
- Very simple file transfer application
- Read files and write files
- No authentication - Not used on production systems
Telnet
Telnet – Telecommunication Network - tcp/23
• Login to devices remotely
• Console access
• In-the-clear communication
• Not the best choice for production systems
DHCP - Dynamic Host Configuration Protocol
• udp/67, udp/68 - Requires a DHCP server
HTTP
HTTPS
HTTP 80
HTTPS 443
SNMP - Simple Network Management Protocol
udp/161
RDP - Remote Desktop Protocol
Share a desktop from a remote location over tcp/3389
NTP - Network Time Protocol
Every device has its own clock - udp/123
SIP - Session Initiation Protocol
Voice over IP (VoIP) signaling
• tcp/5060 and tcp/5061
SMB - 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
POP/IMAP
POP/IMAP
• Receive emails from an email server
• Authenticate and transfer
• POP3 - Post office Protocol version 3 - tcp/110
• Basic mail transfer functionality
• IMAP4 - Internet Message Access Protocol v4 - tcp/143
• Manage email inbox from multiple clients
LDAP/LDAPS
LDAP (Lightweight Directory Access Protocol) - tcp/389
• Store and retrieve information in a network directory
• LDAPS (LDAP Secure) - tcp/636
• A non-standard implementation of LDAP over SSL
H.323
Voice over IP (VoIP) signaling - tcp/1720
• ITU Telecommunication H.32x protocol series
Open Systems Interconnection Reference Model
- It’s a guide (thus the term “model”)
- Don’t get wrapped up in the details
- This is not the OSI protocol suite
- Most of the OSI protocols didn’t catch on
- There are unique protocols at every layer
- You’ll refer to this model for the rest of your career
Layer 1 - The Physical Layer
The physics of the network • Signaling, cabling, connectors • This layer isn’t about protocols • You have a physical layer problem.” • Fix your cabling, punch-downs, etc. • Run loopback tests, test/replace cables, swap adapter cards
Layer 2 - Data Link Layer
• The basic network “language” • The foundation of communication at the data link layer • Data Link Control (DLC) protocols • MAC (Media Access Control) address on Ethernet • The “switching” layer
Layer 3 - The Network Layer
• The “routing” layer
• Internet Protocol (IP)
• Fragments frames to traverse different networks
What is IP Fragmentation?
• Fragments are always in multiples of 8 because of the
number of fragmentation offset bits in the IP header
Layer 4 - Transport Layer
• The “post office” layer
• Parcels and letters
• TCP (Transmission Control Protocol) and
UDP (UserDatagram Protocol)
Layer 5 - Session Layer
Communication management between devices
• Start, stop, restart
• Half-duplex, full-duplex
• Control protocols, tunneling protocols
Layer 6 - Presentation Layer
Character encoding
• Application encryption
• Often combined with the Application Layer
