Debug command was the old way of capturing the packets. This command has been deprecated in 7.x versions. There is a better way available to capture the packets. For that we can use the "capture" command. Here is an example-

suppose there is a host a.a.a.a on the inside interface of PIX/ASA and I need to capture all the outbound packets from this host. For this, I can apply captures using folloaing commands-

-> access-list capi permit ip host a.a.a.a any

-> capture cpi access-list capi buffer 1000000 packet-length 1518 interface inside

Using access-list gives me more strength and granularity to capture only the packets I need. Later I use that access-list in the capture command. To download the capture files, I need to point my browser to-

https://interface_ip/capture/cpi/pcap

(assuming PDM/ASDM is installed)

You can also use "copy" command to transfer the capture file to a tftp server.

Link for capture command-

http://www.cisco.com/univercd/cc/td/doc/product/multisec/asa_sw/v_70/cref_txt/c.htm#wp1950270

Link for copy command-

http://www.cisco.com/univercd/cc/td/doc/product/multisec/asa_sw/v_70/cref_txt/c.htm#wp1970556

Hope this is helpful.

Regards,

Vibhor.