# Strong IKEv2 Policy (Cisco ASA)
crypto ikev2 policy 10
 encryption aes-256 aes-128
 integrity sha256 sha384
 group 19 20 14
 prf sha256 sha384
 lifetime seconds 28800

# Strong IPsec Proposal
crypto ipsec ikev2 ipsec-proposal STRONG-ESP
 protocol esp encryption aes-256 aes-128
 protocol esp integrity sha256 sha384

# Certificate-based Authentication (Recommended)
crypto ikev2 profile CERT-PROFILE
 match identity remote any
 identity local dn
 authentication remote rsa-sig
 authentication local rsa-sig
 pki trustpoint ENTERPRISE-CA
 pki cert-map 10 subject-name attr cn eq REMOTE-PEER-CN

# Cisco ASA Performance Tuning
# Enable hardware acceleration
crypto engine accelerator ipsec

# Optimize connection limits
vpn load-balancing
vpn-concurrent-user-limit 500
vpn-session-limit 1000

# CPU and memory optimization
cpu-allocation ipsec-crypto 50
memory-allocation crypto 25

# Interface optimization
interface outside
 speed 1000
 duplex full
 mtu 1500

# Enable hardware crypto acceleration
echo 'aesni-intel' >> /etc/modules
echo 'ghash-clmulni-intel' >> /etc/modules

# Optimize network stack
echo 'net.core.rmem_max = 16777216' >> /etc/sysctl.conf
echo 'net.core.wmem_max = 16777216' >> /etc/sysctl.conf
echo 'net.ipv4.tcp_rmem = 4096 87380 16777216' >> /etc/sysctl.conf
echo 'net.ipv4.tcp_wmem = 4096 65536 16777216' >> /etc/sysctl.conf

# XFRM (IPsec) specific tuning
echo 'net.xfrm.larval_drop = 0' >> /etc/sysctl.conf
echo 'net.ipv4.xfrm4_gc_thresh = 32768' >> /etc/sysctl.conf

# Apply settings
sysctl -p

# Enable SNMP on Cisco ASA
snmp-server host 192.168.1.100 community public version 2c
snmp-server location "Data Center 1"
snmp-server contact "network-team@company.com"
snmp-server community public ro
snmp-server enable traps ipsec start stop

# Key SNMP OIDs for IPsec monitoring
# Tunnel Status: 1.3.6.1.2.1.1.3.0 (sysUpTime)
# Interface Statistics: 1.3.6.1.2.1.2.2.1.10 (ifInOctets)
# CPU Utilization: 1.3.6.1.4.1.9.2.1.58.0 (avgBusy5)
# Memory Utilization: 1.3.6.1.4.1.9.2.1.8.0 (memUsed)

# Configure centralized logging
logging enable
logging buffered warnings
logging host 192.168.1.101
logging trap informational
logging facility 16

# Enable IPsec-specific logging
logging message 713236 level 6  # IPsec SA established
logging message 713906 level 4  # Group authentication failure
logging message 713225 level 6  # IPsec SA deleted
logging message 725001 level 4  # DPD failure detected

# Log format for analysis
logging timestamp
logging host 192.168.1.101

#!/bin/bash
# IPsec Health Check Script

REMOTE_PEER="203.0.113.1"
LOCAL_SUBNET="192.168.1.0/24" 
REMOTE_SUBNET="192.168.2.0/24"
LOG_FILE="/var/log/ipsec-health.log"

# Function to log with timestamp
log_message() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" >> $LOG_FILE
}

# Check tunnel status
check_tunnel_status() {
    if ipsec status | grep -q "ESTABLISHED"; then
        log_message "INFO: IPsec tunnel is UP"
        return 0
    else
        log_message "ERROR: IPsec tunnel is DOWN"
        return 1
    fi
}

# Test connectivity through tunnel
test_connectivity() {
    if ping -c 3 -W 5 192.168.2.1 > /dev/null 2>&1; then
        log_message "INFO: Connectivity test PASSED"
        return 0
    else
        log_message "ERROR: Connectivity test FAILED"
        return 1
    fi
}

# Check certificate expiration
check_cert_expiry() {
    DAYS_LEFT=$(openssl x509 -in /etc/ipsec.d/certs/vpn-cert.pem -noout -enddate | \
                cut -d= -f2 | xargs -I {} date -d {} +%s | \
                awk -v now=$(date +%s) '{print int(($1-now)/(60*60*24))}')
    
    if [ $DAYS_LEFT -lt 30 ]; then
        log_message "WARNING: Certificate expires in $DAYS_LEFT days"
    else
        log_message "INFO: Certificate valid for $DAYS_LEFT days"
    fi
}

# Main execution
log_message "Starting IPsec health check"
check_tunnel_status
test_connectivity  
check_cert_expiry
log_message "Health check completed"

# Capacity Planning Formula

Required Bandwidth = (Peak Users × Average Bandwidth per User × Growth Factor)

Where:
- Peak Users: Maximum concurrent VPN users
- Average Bandwidth: Application-specific (email: 0.1 Mbps, file transfer: 2 Mbps)
- Growth Factor: 1.5-2.0 for 3-5 year planning

Example Calculation:
- 500 peak users
- 1 Mbps average per user (mixed applications)
- 1.5 growth factor
- Required Bandwidth = 500 × 1 × 1.5 = 750 Mbps

Hardware Sizing:
- CPU: 2-4 cores per 100 Mbps encrypted throughput
- RAM: 1 GB per 1000 concurrent sessions
- Storage: 100 GB minimum for logs and certificates