ASA5520: proxyarp question

Answered Question
Mar 24th, 2008

I understand that proxyarp is enabled by default on the fw....with this enabled would it cause internal network routing issues? (responding to arp requests) should proxyarp be enabled for outside interface as well?


currently i have it DISABLED but not able to reach server which has static translation config'd unless i enable it.


thanks for any info

Correct Answer by Jon Marshall about 8 years 11 months ago

Hi


You need proxyarp enabled if you want the ASA to respond to arps for static translations eg.


static (inside,outside) 193.10.10.10 192.168.5.10 netmask 255.255.255.255


If a machine on the outside arps out for 193.10.10.10 then the ASA needs to respond with it's outside interfaces mac-address and then when the packet is forwarded to the ASA it then translates it to 192.168.5.10 and forwards it on through it's inside interface.


However you can disable proxyarp on a per interface basis so if you think it is causing problems you could try disabling it on your inside interface only.


Please see attached link for details


http://www.cisco.com/en/US/docs/security/asa/asa70/command/reference/s.html#wp1542397


HTH


Jon

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Correct Answer
Jon Marshall Mon, 03/24/2008 - 06:34

Hi


You need proxyarp enabled if you want the ASA to respond to arps for static translations eg.


static (inside,outside) 193.10.10.10 192.168.5.10 netmask 255.255.255.255


If a machine on the outside arps out for 193.10.10.10 then the ASA needs to respond with it's outside interfaces mac-address and then when the packet is forwarded to the ASA it then translates it to 192.168.5.10 and forwards it on through it's inside interface.


However you can disable proxyarp on a per interface basis so if you think it is causing problems you could try disabling it on your inside interface only.


Please see attached link for details


http://www.cisco.com/en/US/docs/security/asa/asa70/command/reference/s.html#wp1542397


HTH


Jon

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