How to Defend Against Sniffing
- Restrict the physical access to the network media to ensure that a packet sniffer cannot be installed.
- Use encryption to protect confidential information.
- Permanently add the MAC address of the gateway to the ARP cache.
- Use static IP addresses and static ARP tables to prevent attackers from adding the spoofed ARP entries for machines in the network.
- Turn off network identification broadcasts and if possible restrict the network to authorized users in order to protect network from being discovered with sniffing tools.
- Use IPv6 instead of IPv4 protocol.
- Use encrypted sessions such as SSH instead of Telnet, Secure Copy (SCP) instead of FTP, SSL for email connection, etc. to protect wireless network users against sniffing attacks.
- Use HTTPS instead of HTTP to protect user names and passwords.
- Use switch instead of hub as switch delivers data only to the intended recipient.
- Use SFTP, instead of FTP for secure transfer of files.
- Use PGP and S/MIPE, VPN, IPSec, SSL/TLS, Secure Shell (SSH) and One-time passwords (OTP).
- Always encrypt the wireless traffic with a strong encryption protocol such as WPA and WPA2.
- Retrieve MAC directly from NIC instead of OS; this prevents MAC address spoofing.
- Use tools to determine if any NICs are running in the promiscuous mode.
Q1) Which of the following is not a defense against sniffing?
- Encrypting communication
- Implementing port security on all switches
- Moving to an all-switched network
- Using hubs within the network
A1) Using a hub within a network actually makes life easier on the sniffer. A fully switched network and port security frustrate such efforts. Encryption is, by far, the best option.