TCP/IP Applications Flashcards
session
any communication between one computer and another
TCP
Transmission Control Protocol
- enables connection oriented communications in networks that use TCP/IP protocol suite
How does TCP connect
TCP three-way handshake
- client send single SYN segment to server
- server return a single SYN, ACK segment
- client sends single ACK segment and request server begins sending data
- once server finishes, sends a FIN segment
- client responds with ACK, then sends FIN
- server responds with ACK
- both parties consider session closed
DHCP ports
UDP 67 for client
UDP 68 for server
Synchronize time
NTP - Network Time Protocol
SNTP - Simple Network Time Protocol
Both use UDP 123
TFTP
Trivial File Transfer Protocol
- UDP port 69
- only used on same LAN
ICMP
Internet Control Message Protocol
- works at layer 3
- UDP
- ping is an example
What is the reply to a ping request called?
echo reply
ping of death
sending a malformed ping packet to cause destination computer to crash
IGMP
Internet Group Managment Protocol
- enables routers to communicate with hosts to determine a group “memebership”
port number
- 16 bit value
- between 0 and 65535
- 0 to 1023 are well-known port numbers (reserved for specific applications)
- 1024 to 5000 are ephemeral port numbers
- 49152 to 65535 are dynamic or private port numbers
Session information (IP address and port number) are stored in?
socket or endpoint
Session data stored for two computers about the same connection
socket pairs or endpoints
Term for session information and session data
connection or session
View endpoints on Windows CLI
netstat -n
a socket that is prepared to respond to any IP packets destined for that port
open port or listening port
View open ports on Windows CLI
netstat -an
netstat states
listening - open, waiting for connection
established - port is connected
close_wait - closed
View process IDs in netstat
netstat -o
View program names in netstat
netstat -b
find process ID in linux
ps
Why set a connection limit on IIS
- based on avialable memory and bandwidth
- prevent DOS attacks
URL
Uniform Resource Locator
What does an internet application need to be secure?
authentication - user names and passwords
encryption - stirring up the data
nonrepudiation - source is not able to deny a sent message
SSL/TLS
Secure Sockets Layer / Tranport Layer Security
HTTPS port
TCP 443
Telnet port
TCP 23
SSH port
TCP 22
SMTP port
TCP 25
POP3 port
TCP 110
IMAP4 port
TCP 143
3 main email servers
Exim, postfix and exchange
FTP port
TCP ports 21 and 20
passive FTP only uses port 21
use passive FTP with NAT
TFTP port
UDP port 69
Protocol developed by netscape for transmitting private documents
SSL
netstat show all used ports
netstat -a
netstat show raw port numbers and ip addresses
netstat -n
