Cisco ASA version 7 NTP sync with ISP modem

[Rahul Kapadia]

Hello, 

I'm facing issue related to NTP from ISP to inside host

TOPOLOGY: ISP modem--->Outside_Int--->ASA--->Inside_Int

ACL:

access-list VLAN100_IN extended permit tcp any any eq www
access-list VLAN100_IN extended permit tcp any any eq https
access-list VLAN100_IN extended permit udp any any eq domain
access-list VLAN100_IN extended permit udp any any eq ntp
access-list VLAN20_IN extended permit tcp any any eq www
access-list VLAN20_IN extended permit tcp any any eq https
access-list VLAN20_IN extended permit udp any any eq domain

NTP:
ntp authentication-key 1 md5 *
ntp authenticate
ntp trusted-key 1
ntp server 192.168.100.1 source VLAN100

ISP modem IP: 192.168.100.1

outside int IP: 192.168.100.50

Inside int VLAN100 IP: 192.168.1.1

Inside int VLAN20 IP: 192.168.2.1

I want that ASA capture time from ISP modem and deliver it to inside host

[Marvin Rhoads]

Do you have confirmation that the ISP modem supports operation as an NTP server with authentication?

It would be unusual to see that offered.

More commonly we would use an Internet-based NTP server. There are some that offer authenticated NTP if you register with them.

[MHM Cisco World]

As I know the ASA can not be NTP Server,

so only way here is bypass NTP from client to ISP NTP Server through ASA.