What Does 'peers: 0' Mean in VPN IKE Gateway List?
An administrator runs 'diagnose vpn ike gateway list' on a FortiGate and sees the following output for a dial-up IPsec VPN: gateway name: 'dialup' version: IKEv1 mode: aggressive local IP: 203.0.113.1 remote IP: 0.0.0.0 state: up peers: 0 What does 'peers: 0' indicate?
Quick Answer
The answer is that 'peers: 0' indicates no IPsec clients are currently connected to the dial-up VPN gateway. This output means the FortiGate’s IKE gateway is up and listening for incoming connections, but no remote clients have successfully completed Phase 1 negotiation to establish a security association. In the Fortinet NSE 4 Network Security Professional exam, this tests your ability to interpret diagnostic output for dial-up VPNs, where a common trap is confusing a "state: up" gateway with active connections—the gateway can be ready without any peers attached. Remember, "peers: 0" equals zero active tunnels, not a broken configuration. A useful memory tip: think of the gateway as a phone that’s powered on (state: up) but has no one on the line (peers: 0).
⚠ Common exam trap
The trap here is that candidates see 'state: up' and assume the gateway has active connections, but 'up' only indicates the IKE process is running and listening, not that any peers are actually connected.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No IPsec clients are currently connected
In the output of 'diagnose vpn ike gateway list', the 'peers' field shows the number of active IPsec tunnels (Phase 1 SAs) currently established through that gateway. A value of '0' means no remote clients have successfully completed IKE negotiation and are connected. Since the gateway state is 'up', it is ready to accept connections, but no clients are currently associated with it.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The remote IP should be set to a specific address
Why it's wrong here
Remote IP 0.0.0.0 is normal for dial-up gateways.
- ✗
The gateway is in a down state
Why it's wrong here
The state is 'up', so the gateway is operational.
- ✓
No IPsec clients are currently connected
Why this is correct
Peers: 0 indicates zero active connections.
- ✗
The Phase 2 proposals are mismatched
Why it's wrong here
Phase 2 is not reflected in 'gateway list' output.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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Same concept, more angles
1 more way this is tested on NSE4
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A FortiGate administrator runs 'diagnose vpn tunnel list' and sees the following output for an IPsec tunnel: 'status: up', 'incoming: 0 packets', 'outgoing: 100 packets'. Phase 1 and Phase 2 both show state 'up'. What is the MOST likely cause of zero incoming packets?
hard- A.The remote gateway is using aggressive mode
- B.The FortiGate has a static route pointing to the VPN interface
- C.The VPN is configured in policy-based mode
- ✓ D.The Phase 2 proposal includes a mismatched proxy ID
Why D: The output shows the VPN tunnel is up with outgoing packets but zero incoming packets. This indicates a Phase 2 mismatch, most commonly due to mismatched proxy IDs (local/remote subnets). When proxy IDs do not match between peers, the tunnel establishes but traffic is not correctly matched, causing the remote gateway to drop or not send traffic to the FortiGate, resulting in zero incoming packets.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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