I believe it is on by default. Looking at my firewalls (6.3 versions) it looks to be on.
Excerpt from Cisco doc:--
Check to see if proxy ARP is disabled. Issue the command show running-config sysopt in PIX/ASA 7.x or show sysopt in PIX 6.x.
Here proxy ARP is disabled by the command sysopt noproxyarp outside:
ciscoasa#show running-config sysopt
no sysopt connection timewait
sysopt connection tcpmss 1380
sysopt connection tcpmss minimum 0
no sysopt nodnsalias inbound
no sysopt nodnsalias outbound
no sysopt radius ignore-secret
sysopt noproxyarp outside
sysopt connection permit-vpn
In order to re-enable proxy ARP, enter this command in global configuration mode:
ciscoasa(config)#no sysopt noproxyarp outside
When i checked my firewalls there was no
sysopt noproxyarp "interface" statements so i'm assuming this means it is on by default.
HTH
