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Mon, May 8, 2017 11:00 AM

Cisco ASA 5520 behind SMC Business Gateway not getting all IP's

I'm having a strange issue that I'm not sure how to address.  I have a Comcast SMC Business Gateway/Cable modem.  We have 5 staic IP addresses.  Behind my cable modem connected to one of the switch ports on the SMC is a Cisco ASA 5520 firewall.  I have the the lowest IP of my block of IP's assigned to the interface on the ASA.  I can not ping this IP, nor can I set up a site to site VPN also running a Cisco ASA firewall at a remote site.  I have NAT rules setup on my ASA to point different public IP's to different services inside my network.  I **can** ping the two IP's in my Static IP range that have NAT setup on them.  I should be able to ping my interface IP from the external world.  I have allowed ICMP/ECHO requests on the interface.  The SMC Cable modem is in the bridged mode configuration.  I'm simply looking for an Ethernet handoff and have my equipment (i.e. the ASA) do all the NAT, Firewall, etc, etc).  Any suggestions on what I can try?  I've contacted Comcast via phone and they don't know what's wrong, or what to suggest.  It's just strange that I can ping public IP's that I have NAT rules setup for, but I can't even ping the firewall's Public IP...


Forum Contributor


306 Messages

4 y ago

Get a different model of firewall - such as the free pfsense - and try configuring it as a test.  Or just throw a Linux box in there and try configuring that as a NAT or a plain old Cisco router.


ASA configurations are VERY complex and the devices do a LOT of very stupid, braindead, weird things.  You need to eliminate the possibility that you have misconfigured the ASA first.


(Frankly, unless you are paying for a Firepower module subscription on an ASA they are not worth the trouble.  The Cisco RV320 is a lot easier to deal with.)