IPSec Phase 1 negotiation fails with "NO_PROPOSAL_CHOSEN" seen in System Logs - Authentication mismatch in Phase 1

IPSec Phase 1 negotiation fails with "NO_PROPOSAL_CHOSEN" seen in System Logs - Authentication mismatch in Phase 1

9690
Created On 07/28/22 21:13 PM - Last Modified 08/03/22 22:48 PM


Symptom


  • VPN Tunnel not coming up or went down
  • System Logs showing "no proposal chosen."
  • System Logs showing "<IKEGateway> unauthenticated NO_PROPOSAL_CHOSEN received, you may need to check IKE settings"
  • CLI show command outputs on the two peer firewalls showing different Authentication algorithms (Example: SHA-512 vs. SHA-384)
  • Packet Capture showing "NO_PROPOSAL_CHOSEN" in the IKE packets (UDP port 500)
Web UI
Navigate to Network > IKE Crypto Profile > edit IKE Crypto Profile > edit Authentication
Comparing Web UI for Phase 1 Authentication mismatch

CLI
On both VPN peers, run the below command(s) via CLI
>show vpn gateway name <name>
FW1> show vpn gateway name IKEGatewayTest1
GwID   Name          Peer-Address/ID                Local Address/ID                 Proposals    
1   IKEGatewayTest1   203.0.113.200                    203.0.113.100            [PSK][DH20][AES256][SHA512]
FW2> show vpn gateway name IKEGatewayTest1
GwID   Name          Peer-Address/ID                Local Address/ID                 Proposals    
1   IKEGatewayTest1   203.0.113.100                    203.0.113.200            [PSK][DH20][AES256][SHA384]


System Logs
Navigate to Monitor > System Logs
Comparing System Logs for Phase 1 Authentication mismatch

Wireshark
Take a packet capture on both VPN peers and open them in Wireshark side-by-side
Comparing Wireshark for Phase 1 Authentication mismatch
This will cause the VPN negotiation to fail with this message:
Wireshark no proposal phase 1 authentication

ikemgr.log
Run the below command via CLI on both peers

>less mp-log ikemgr.log
2022-06-27 12:44:49 [PWRN]: [IKEGatewayTest1:342] IKEv2 proposal doesn't match, please check crypto setting on both sides.
2022-06-27 12:44:49 [PERR]: no proposal chosen.
2022-06-27 12:44:52 [PWRN]: [IKEGatewayTest1:341] unauthenticated NO_PROPOSAL_CHOSEN received, you may need to check IKE settings.


Environment


  • PAN-OS
  • Palo Alto Networks firewall configured with IPSec VPN Tunnel


Cause


This issue occurs when the two VPN peers have a mismatch in Authentication algorithm

Resolution


  1. Configure both sides of the VPN to have a matching Authentication algorithm

Comparing GUI for matching Authentication phase 1
(If your VPN peer is a different vendor firewall, perform their equivalent/same Phase 1 Authentication configuration change on their firewall if they are the source of the mismatch)

  1. Perform a Commit
  2. Run the below commands a couple times each on both the VPN peer firewall CLIs to get them to freshly initiate and form:
>clear vpn ike-sa gateway <name>
>clear vpn ipsec-sa tunnel <name>


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    https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u000000wlAsCAI&lang=en_US&refURL=http%3A%2F%2Fknowledgebase.paloaltonetworks.com%2FKCSArticleDetail

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