CSNT 181 FINAL EXAM 2025/2026
GRADED A+
(VERIFIED)
Each OSI layer has its own set of roles and protocols - security isn't tied to any particular layer, you
could apply encryption at every layer but it would damage compatibility/performance.
Secure Socket Layer - Most widespread standard for securing the upper layers of the network along
with its successor Transport Layer Security (Layer 5 - Session or Layer 6 Presentation). They lie
somewhere between application protocols themselves, and the Transport layer protocols used by
the TCP/IP stack
Transport Layer Security (TLS) - a cryptographic protocol that ensures data security and integrity over
public networks, such as the Internet. Supports newer encryption standards and fixes security issues.
Public key certificates are generically called SSL certificates even when they're not used for SSL at all.
SSL and TLS use certificate-based authentication, then perform a key exchange to set up a
symmetrically encrypted communication session that lasts until the connection is broken. - When
you connect to an SSL-secured website, the server's certificate allows your browser to authenticate
that the server is genuine. SSL/TLS can perform two-way authentication where both the client and
server must have a certificate to present to the other.
Cipher suites - several algorithms used within a single protocol - TLS session requires a public key
cipher for key exchange, a symmetric cipher for bulk encryption, a hashing algorithm to validate
certificates and a pseudorandom number generator to create session keys and nonces. During a
session both parties have to use cipher suite that entirely match each other.
HTTP vs. HTTPS - Data transmitted using HTTP may be visible to a man in the middle as it is not
encrypted. Whereas HTTPS is encrypted so even if the data is intercepted it won't be decipherable.
Syntax and function are the same, the difference is that the browser and server both pass HTTP
traffic thru TLS in HTTPS.
Implementing a cryptosystem is prone to error so most clients/servers rely on 3rd party TLS libraries
to perform these functions. - OpenSSL is a general purpose library; centrepiece is an API developers
can use for their applications which can perform the following:
store/verify certificates & signatures
key generation/encryption for public secret key
, create self-signed certificates
establish private root
If you're not a software developer you can interact with the API using the openssl command - use it
create keys/hashes, verify hashes or certificates, determine what versions of SSL a web server
supports, password-encrypt a file.
High volume servers can benefit from TLS accelerators - Offloading encryption to specialized devices
takes stress of the server
Sometimes encryption is undesirable in a trusted SSL network - it can impair traffic monitoring so
place SSL decryptors on network boundaries to open/inspect TLS traffic.
Common Network Services - Typical enterprise networks rely on many protocols for vital services;
secure alternatives can replace insecure protocols
DHCP - Operates on UDP port 67 for servers and UDP port 68 for clients; no inherent security so easy
for attackers to deploy rogue DHCP servers to enable attacks use snooping feature to counter.
DNS - UDP port 53 client-server & TCP port 53 for server-server no inherent security; susceptible to
DNS poisoning attacks fill cache with false information. Counter with DNSSEC extensions authenticate
responses with crypto signatures or DNS-over-TLS or VPN
Network Time Protocol (NTP) - synchronizes clocks between network devices used to keep accurate
system logs, etc. Susceptible to DoS or MitM attacks requires updated software and secure
configuration of time services. uses UDP port 123
Lightweight Directory Access Protocol - manages distributed directory information services across a
network. Allows clients to query a central network database for user accounts, printers, and other
network resources. isn't secure so use LDAP over SSL or LDAPS. LDAP TCP port 389 or LDAPS uses TCP
port 636.
NetBIOS (Network Basic Input/Output System) - A session-layer API for network applications, rather
than an application protocol used for file and printer sharing as well as computer identification on
local network segments. NetBIOS uses TCP and UDP ports 137-139.
GRADED A+
(VERIFIED)
Each OSI layer has its own set of roles and protocols - security isn't tied to any particular layer, you
could apply encryption at every layer but it would damage compatibility/performance.
Secure Socket Layer - Most widespread standard for securing the upper layers of the network along
with its successor Transport Layer Security (Layer 5 - Session or Layer 6 Presentation). They lie
somewhere between application protocols themselves, and the Transport layer protocols used by
the TCP/IP stack
Transport Layer Security (TLS) - a cryptographic protocol that ensures data security and integrity over
public networks, such as the Internet. Supports newer encryption standards and fixes security issues.
Public key certificates are generically called SSL certificates even when they're not used for SSL at all.
SSL and TLS use certificate-based authentication, then perform a key exchange to set up a
symmetrically encrypted communication session that lasts until the connection is broken. - When
you connect to an SSL-secured website, the server's certificate allows your browser to authenticate
that the server is genuine. SSL/TLS can perform two-way authentication where both the client and
server must have a certificate to present to the other.
Cipher suites - several algorithms used within a single protocol - TLS session requires a public key
cipher for key exchange, a symmetric cipher for bulk encryption, a hashing algorithm to validate
certificates and a pseudorandom number generator to create session keys and nonces. During a
session both parties have to use cipher suite that entirely match each other.
HTTP vs. HTTPS - Data transmitted using HTTP may be visible to a man in the middle as it is not
encrypted. Whereas HTTPS is encrypted so even if the data is intercepted it won't be decipherable.
Syntax and function are the same, the difference is that the browser and server both pass HTTP
traffic thru TLS in HTTPS.
Implementing a cryptosystem is prone to error so most clients/servers rely on 3rd party TLS libraries
to perform these functions. - OpenSSL is a general purpose library; centrepiece is an API developers
can use for their applications which can perform the following:
store/verify certificates & signatures
key generation/encryption for public secret key
, create self-signed certificates
establish private root
If you're not a software developer you can interact with the API using the openssl command - use it
create keys/hashes, verify hashes or certificates, determine what versions of SSL a web server
supports, password-encrypt a file.
High volume servers can benefit from TLS accelerators - Offloading encryption to specialized devices
takes stress of the server
Sometimes encryption is undesirable in a trusted SSL network - it can impair traffic monitoring so
place SSL decryptors on network boundaries to open/inspect TLS traffic.
Common Network Services - Typical enterprise networks rely on many protocols for vital services;
secure alternatives can replace insecure protocols
DHCP - Operates on UDP port 67 for servers and UDP port 68 for clients; no inherent security so easy
for attackers to deploy rogue DHCP servers to enable attacks use snooping feature to counter.
DNS - UDP port 53 client-server & TCP port 53 for server-server no inherent security; susceptible to
DNS poisoning attacks fill cache with false information. Counter with DNSSEC extensions authenticate
responses with crypto signatures or DNS-over-TLS or VPN
Network Time Protocol (NTP) - synchronizes clocks between network devices used to keep accurate
system logs, etc. Susceptible to DoS or MitM attacks requires updated software and secure
configuration of time services. uses UDP port 123
Lightweight Directory Access Protocol - manages distributed directory information services across a
network. Allows clients to query a central network database for user accounts, printers, and other
network resources. isn't secure so use LDAP over SSL or LDAPS. LDAP TCP port 389 or LDAPS uses TCP
port 636.
NetBIOS (Network Basic Input/Output System) - A session-layer API for network applications, rather
than an application protocol used for file and printer sharing as well as computer identification on
local network segments. NetBIOS uses TCP and UDP ports 137-139.
