Denial of Service on Outside Interface

[Fazil Haneefa]

Hi Guys,

Today I encountered a strange problem with our WAN firewall (ASA 5520). The clients from outside were not able to connect to the services inside. Even from the WAN router I was not able to ping the services inside for about 40 minutes. The solar winds showed me that there was lot of discards on the outside interface, around 300 k during this time.

Any idea how to investigate what really happened during this time period. I am confused now and I have to give an explanation to the higher management and I didn't do anything but it solved by its own after this time period.

[Aditya Ganjoo]

Hi Fazil,

There can be a lot of reasons behind this.From the inside were we able to reach the internet ?

Also what was the resource usage on the ASA as in:

show service-policy
show asp drop
show counters
show traffic
show interface
show process
show conn count
show xlate count
show perfmon

Do you have syslogs at the time of the issue ?

We need to check all this info and correlate them.

Regards,

Aditya

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