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In cybersecurity, everything goes through the network. If you don’t know how data flows, you can’t protect it:
- Hub: Sends everything to everyone → No confidentiality, ideal for sniffing attacks.
- Switch: Sends data to the correct machine via MAC address → More secure but vulnerable to network attacks (e.g., MAC flooding).
- Router: Connects multiple networks, applies rules (IP, NAT, VPN) → Filters traffic, isolates segments, and logs connections.
Understanding these devices helps in:
- Placing security tools (firewalls, IDS/IPS) correctly.
- Segmenting the network to limit attack spread.
- Analyzing and controlling traffic during incidents.
You Should Know:
1. Hub Security Risks & Detection
Since hubs broadcast all traffic, they are prime targets for sniffing. Detect sniffers with:
sudo tcpdump -i eth0 -n -c 100
Check for unusual ARP traffic (indicates ARP spoofing):
sudo arpwatch -i eth0
### **2. Switch Security & Mitigation**
Switches use MAC tables, but attackers can flood them:
**Prevent MAC Flooding:**
sudo macof -i eth0 -n 1000 # Simulate MAC flooding (for testing)
**Enable Port Security (Cisco Example):**
switch(config-if)# switchport port-security switch(config-if)# switchport port-security maximum 5 switch(config-if)# switchport port-security violation restrict
### **3. Router Security & Hardening**
Routers control traffic flow. Secure them with:
**Block ICMP Ping (Linux Router):**
sudo iptables -A INPUT -p icmp --icmp-type echo-request -j DROP
**Enable NAT (IP Masquerading):**
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
**Log Suspicious Traffic:**
sudo iptables -A INPUT -p tcp --dport 22 -j LOG --log-prefix "SSH Attempt: "
### **4. Network Segmentation (Best Practice)**
Isolate critical systems using VLANs:
**Linux VLAN Setup:**
sudo vconfig add eth0 10 # Create VLAN 10 sudo ifconfig eth0.10 up
**Windows VLAN (PowerShell):**
New-NetLbfoTeam -Name "VLAN-Team" -TeamMembers "Ethernet1","Ethernet2" -TeamingMode SwitchIndependent
## **What Undercode Say:**
Understanding network devices is crucial for cybersecurity. Hubs are obsolete due to security flaws, while switches and routers form the backbone of secure networks. Always:
– Monitor ARP & MAC tables for anomalies.
– Segment networks to limit breach impact.
– Log & filter traffic at routers.
– Disable unused ports on switches.
For deeper security:
- Use SNMP monitoring (
snmpwalk -v2c -c public <IP>). - Implement 802.1X authentication on switches.
- Regularly audit firewall rules (
iptables -L -v -n).
## **Expected Output:**
A hardened network with:
- Switches protected against MAC flooding.
- Routers filtering malicious traffic.
- Segmented VLANs isolating critical assets.
- Logs tracking unauthorized access attempts.
**Further Reading:**
References:
Reported By: Biren Bastien – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
