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HSRP (Hot Standby Router Protocol) and VRRP (Virtual Router Redundancy Protocol) are critical for ensuring high availability in networks. However, they can be vulnerable to attacks if not properly secured. Below are best practices for securing both protocols.
Securing HSRP (Cisco Proprietary)
1️⃣ Enable Authentication
Use MD5 authentication to prevent rogue routers from joining the HSRP group.
interface GigabitEthernet0/1 standby version 2 standby 1 authentication md5 key-string MySecureKey standby 1 preempt standby 1 ip 192.168.1.1
#### **2️⃣ Use Access Control Lists (ACLs)**
Restrict HSRP traffic to trusted routers only.
access-list 100 permit udp host 192.168.1.2 host 224.0.0.2 eq 1985 access-list 100 deny udp any any eq 1985 access-list 100 permit ip any any
#### **3️⃣ Enable Interface Tracking**
Ensure failover if a critical interface goes down.
interface GigabitEthernet0/1 standby 1 track GigabitEthernet0/2 30
#### **4️⃣ Use HSRP Version 2**
HSRPv2 provides better security and IPv6 support.
interface GigabitEthernet0/1 standby version 2
#### **5️⃣ Limit VLAN Access**
Prevent unauthorized devices from joining the HSRP VLAN.
switchport mode access switchport access vlan 10 switchport port-security maximum 2
### **Securing VRRP (Open Standard)**
#### **1️⃣ Enable Authentication**
Use MD5 authentication to secure VRRP messages.
interface GigabitEthernet0/1 vrrp 1 authentication md5 key-string SecureVRRPKey
#### **2️⃣ Restrict VRRP Multicast Traffic**
Block unauthorized VRRP advertisements.
access-list 110 permit udp host 192.168.1.2 host 224.0.0.18 eq 112 access-list 110 deny udp any any eq 112
#### **3️⃣ Use Interface Tracking**
Monitor critical interfaces for failover.
interface GigabitEthernet0/1 vrrp 1 track interface GigabitEthernet0/2 decrement 20
#### **4️⃣ Set VRRP Priority & Preemption**
Control master election securely.
interface GigabitEthernet0/1 vrrp 1 priority 120 vrrp 1 preempt delay minimum 60
#### **5️⃣ Limit VLAN Access**
Use private VLANs to isolate VRRP traffic.
vlan 20 private-vlan primary private-vlan association 21-22
🔐 Additional Security Best Practices for Both HSRP & VRRP
✅ **Use Private VLANs** – Isolate HSRP/VRRP traffic.
✅ Monitor Logs & Alerts – Detect unauthorized changes.
✅ **Disable Unused Ports** – Reduce attack surface.
✅ **Enable Logging** – Track protocol state changes.
logging buffered 64000 logging trap debugging
### **What Undercode Say**
Securing HSRP and VRRP is essential to prevent man-in-the-middle attacks, rogue router takeovers, and network instability. Always use strong authentication (MD5), restrict protocol traffic via ACLs, and monitor logs for anomalies. Implementing interface tracking ensures seamless failover, while VLAN isolation minimizes exposure to threats.
**Expected Output:**
HSRP/VRRP secured with MD5 auth, ACLs, and interface tracking.
References:
Reported By: Breeze Singh – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
