source: http://www.securityfocus.com/bid/7317/info

Linksys BEFVP4 VPN router has been reported prone to a sensitive information disclosure vulnerability.

It has been reported that SNMP community strings which, are world readble by default, contain sensitive information pertaining to the internal protected network.

Data collected in this manner may be used in further attacks against the victim network.

It should be noted that this issue has also been reported to affect the Linksys BEFSR81 appliance. 

snmpwalk -v 1 -c public {ip}