Networking Security
Network Security
Threats, CIA and AAA, cryptography, device hardening, firewalls, VPNs, information security and policy.
- 26 notes
- 213 minutes of reading
- Why network security matters: attackers, malware and security policyWhy every organisation must protect its network, who attacks networks and why, the main types of malware and how to prevent them, and the role of security policies and CERTs. 7 min · Beginner
- Denial of service, DDoS and social engineering attacksHow DoS and DDoS attacks take services offline (flooding, SYN floods, ICMP attacks, crash attacks), how botnets work, what social engineering is and how to defend against all of them. 7 min · Intermediate
- CIA, data confidentiality and AAA (authentication, authorisation, accounting)How the CIA triad maps to security controls, practical guidelines for keeping data confidential, and how AAA controls who can log in to network devices, what they can do and what is logged, including RADIUS vs TACACS+. 8 min · Intermediate
- Encryption and hashing: ciphers, symmetric and asymmetric keys, MD5, SHA and HMACHow encryption turns plaintext into ciphertext, classic transposition and substitution ciphers, symmetric vs asymmetric algorithms, cryptographic hash functions (MD5 vs SHA) and HMAC. 9 min · Intermediate
- Securing switches and routers: VLANs, port security, DHCP snooping and ACLsHow switches and routers connect a network and how to secure them: VLAN types and benefits, port security, DHCP snooping, standard vs extended access control lists and NAT types. 9 min · Intermediate
- Firewalls, next-generation firewalls, IDS and IPSWhat a firewall does, the main firewall types (packet filtering, stateful, application gateway, NAT firewall), what next-generation firewalls add, and how IDS and IPS detect and stop attacks. 8 min · Intermediate
- VPNs and site-to-site IPsec: types, framework and configurationWhy organisations use VPNs, remote-access vs site-to-site, the IPsec framework (confidentiality, integrity, authentication, key exchange), the five steps of an IPsec tunnel and a configuration example. 9 min · Intermediate
- What is information security? Attacks, CIA and how security is achievedThe meaning of information security, the difference between active and passive attacks, the three key security concepts (CIA), and the main tools for achieving security: encryption, digital signatures and access control. 7 min · Beginner
- Threats, vulnerabilities, risk and risk managementThe core vocabulary of security (vulnerability, threat, risk, countermeasure), the common threats from viruses and worms to zero-day attacks and identity theft, and how organisations manage and analyse risk. 8 min · Beginner
- Network security infrastructure: NAT, firewalls, bastion hosts and DMZHow NAT hides internal addressing, the principles behind firewalls (least privilege, separation of duties), host-based vs network-based firewalls, firewall limits and types, bastion hosts, and why public servers belong in a DMZ. 8 min · Intermediate
- Physical security of IT centres and biometric authenticationHow server rooms and IT centres are physically protected, the three authentication factors, the main biometric methods and their accuracy, and practical steps to prevent theft of equipment and data. 7 min · Beginner
- Security policies, standards, procedures and ISO/IEC 27002What a security policy is, how policies differ from standards, procedures and guidelines, the common types of security policy, and how ISO/IEC 27002 (formerly ISO 17799) guides physical, people and access controls. 8 min · Intermediate
- IT risks, UK computer law and ISO 31000 risk managementRisks from hardware, software, mobile and IoT devices; intellectual property; the UK data protection and Computer Misuse Act rules every IT professional should know; and the ISO 31000 risk management standard. 9 min · Intermediate
- Syslog, SNMP, NTP, network monitoring tools and penetration testingHow syslog messages and severity levels work, SNMP versions and why SNMPv3 matters, why accurate time from NTP is essential, what to look for in monitoring software, and the basics and benefits of penetration testing. 8 min · Intermediate
- Testing network security: test plans and best practicesHow to create a network test plan (objectives, acceptance criteria, schedule, responsibilities, resources, procedures), what a test record looks like, and a checklist of network security best practices. 8 min · Intermediate
- Cisco ASA firewall commands: interfaces, NAT, ACLs and VPNThe important Cisco ASA commands for interfaces and security levels, management access, object NAT, access rules, site-to-site IPsec VPN and verification. 8 min · Advanced
- Playbook: hardening a new access switchA practical security checklist for any new managed switch, with an example Cisco IOS configuration. 10 min · Intermediate
- Layer 2 attacks and defences: MAC flooding, VLAN hopping, spoofing and storm controlWhy the switched LAN is an easy target, how MAC flooding, VLAN hopping, rogue DHCP, ARP spoofing and spanning tree attacks work in principle, and the switch features that stop each one. 9 min · Intermediate
- Web, email and DNS security: secure web gateways, email filtering, protective DNS and browser isolationHow organisations protect the three channels most attacks arrive through: the web, email and DNS. Covers secure web gateways, email filtering with SPF, DKIM and DMARC, protective DNS, encrypted DNS and remote browser isolation. 8 min · Intermediate
- Data loss prevention (DLP): finding, watching and protecting sensitive dataWhat data loss prevention is, where DLP tools watch data (in motion, at rest and in use), how they recognise sensitive information, the actions a policy can take, and how to roll DLP out without disrupting work. 8 min · Intermediate
- Secure remote access: SSL/TLS VPNs, split tunnelling, MFA and ZTNAHow staff connect securely from home or on the road: IPsec and SSL/TLS remote-access VPNs, clientless portals, full versus split tunnelling, hardening the VPN gateway, device posture checks and the move to zero trust network access. 8 min · Intermediate
- Zone-based policy firewall on Cisco IOS: zones, zone pairs and inspection policiesHow a router becomes a stateful firewall using the Cisco IOS zone-based policy firewall: security zones, the self zone, default rules, class maps, policy maps with inspect, pass and drop actions, zone pairs and verification commands. 9 min · Advanced
- Cisco IOS ACLs in practice: wildcard bits, standard and extended ACL examplesHow Cisco IOS access lists are written, numbered, named, edited and applied, how wildcard bits work (including non-contiguous masks), and worked standard and extended ACL examples with verification commands. 9 min · Intermediate
- Extended ACL options: the established keyword and time-based ACLsHow the established keyword lets return TCP traffic back in, why it is not the same as a stateful firewall, and how to build time-based ACLs with time ranges that permit or block traffic during set hours. 8 min · Intermediate
- Infrastructure ACLs: protecting routers and network devices at the edgeWhat an infrastructure ACL (iACL) is, why it protects routers and switches better than per-device rules alone, the four-part structure, an example for an internet edge, and how it works alongside uRPF and control plane policing. 8 min · Advanced
- IPv6 access lists on Cisco IOS: syntax, implicit rules and Neighbour DiscoveryHow IPv6 ACLs differ from IPv4 ACLs on Cisco IOS: named-only syntax, prefix lengths, applying them with ipv6 traffic-filter, the implicit Neighbour Discovery permits, and which ICMPv6 messages you must not block. 8 min · Intermediate