Cisco ASA 5516-X blocks responses from external network

[Eugene.alekseev]

Hi everybody.

Last two days I issued problems with accessing several web-resources (usually - Google) when web-browsers in my network try to accept any content (like shared files, photos, etc.).

On my border ASA I see that google IP services list in "Top 10 Protected servers under SYN attack" list, so it looks like ASA blocks responses from several google IPs.

I have no any IPS system attached to ASA, threat detection is in "enable basec threat detection" state, so I have no idea what's the matter of blocking responses.

Also a number of active connections on Firewall Dashboard are increased in ~4-5 times, but external resouces is completely available

Can anybody help me?

[Eugene.alekseev · Accepted solution]

Problem was on provider side, it just blocked one of the Google addresses range.

P.S. - it always works so - as soon as I post any question - it resolves in near future