zywall 110 failing PCI Compliance port 500(isakmp) — Zyxel

[Solved] The peer is not responding to phase 1 ISAKMP requests Apr 20, 2020 Disable ASA IPSEC over UDP - Cisco Community ipsec over udp (port 10000) is usually blocked by default. If you are referring to be able to use ISAKMP (UDP port 500) and nat-traversal (udp port 4500) - there is no way to 'block' access to those ports once isakmp is enabled short of putting an access-list on the control plane of the ASA. VPN access-list - Cisco Community permit udp any host x.x.x.x eq 500 4500 ! ISAKMP and NAT-Traversal. permit esp any host x.x.x.x ! VPN-Data-Packets when no NAT-Traversal is used. You don't need to allow the protocol AH (Authentication Header), as it is not used for VPNs anymore. Sent from Cisco Technical Support iPad App--

Jan 26, 2018 · crypto isakmp fragmentation Example: Router (config)# crypto isakmp fragmentation Enables fragmentation of large IKE packets into a series of smaller IKE packets to avoid fragmentation at the UDP layer.

Apr 20, 2020 Disable ASA IPSEC over UDP - Cisco Community ipsec over udp (port 10000) is usually blocked by default. If you are referring to be able to use ISAKMP (UDP port 500) and nat-traversal (udp port 4500) - there is no way to 'block' access to those ports once isakmp is enabled short of putting an access-list on the control plane of the ASA.

The TCP and UDP Port Numbers are not visible for a NAT device performing PAT between IPSec Peers, because TCP/UDP headers are encrypted and encapsulated with ESP header. When IPSec is used to secure IPv4 traffic, original TCP/UDP Port Numbers are kept encrypted and encapsulated using ESP. Following image shows how IPSec encapsulates IPv4 datagram.

With ISAKMP/IPSec, the IPSec policy agent may only send responses from queries back to UDP port 500. In this case, it is best for PortQry to use UDP port 500 as the source port for the query. If the IPSec policy agent is running on the computer where PortQry runs, UDP port 500 is unavailable because the policy agent is using the port.