Are you looking for a quick and easy way to authenticate SSH public keys securely? Look no further than an SSHFP record! These DNS resource records store a cryptographic fingerprint of an SSH public key to help verify the authenticity of the key and prevent man-in-the-middle attacks. In this blog, we’ll discuss SSHFP records, how they work, and the advantages of using them in your network.
SSHFP record: Definition
An SSHFP record (Secure Shell Fingerprint Record) is a type of DNS resource record. It stores a cryptographic fingerprint of an SSH public key. This record is stored in the Domain Name System (DNS) and is used to verify the authenticity of an SSH host key which is necessary for secure connections between hosts. It is encrypted with the SHA-256 or SHA-1 hash algorithm and contains information specific to the algorithm used to calculate the fingerprint and the SSH public key. By caching all Signed DNS records, the validity of the host key can be verified quickly and securely by querying the authoritative name servers for the SSHFP record. This record plays a vital role in the Domain Name System Security Extensions (DNSSEC) protocol which guarantees the integrity and origin of data received from a DNS server.
What is SSH and how does it work?
When do we need it?
Secure Shell Fingerprint Records could be really advantageous. But when do you need it? Here are some cases:
- When the security of data transferred between hosts is a priority
- When authentication of SSH host keys is necessary
- When there is a risk of man-in-the-middle attacks
- When troubleshooting authentication problems
- When verifying SSH host keys
- When reducing the number of host keys that need to be manually compared
Disadvantages of SSHFP Record
Although the Secure Shell Fingerprint record has many beneficial uses, there are some disadvantages associated with its use. First, not all systems and protocols are compatible with SSHFP records, meaning there may be times when it is not possible to use them. Additionally, configuration options for Secure Shell Fingerprint records are limited, as only two parts of the record (the algorithm field and the fingerprint type field) are customizable. This can make it difficult for admins to set up and maintain, especially for large networks. Despite these drawbacks, SSHFP records are still a great way to increase the security and speed of authentication, so they should be considered for many applications.
SSHFP record and the other DNS records
SSHFP record vs. A record
The difference between an SSHFP record and a DNS A record is that the Secure Shell Fingerprint record contains a cryptographic fingerprint of the public key for the server or host, while the DNS A record contains the IP address associated with the server or host. The SSHFP record is used to authenticate the DNS A record, ensuring that the server or host is authentic and not a malicious actor attempting to spoof a valid server or host.
SSHFP record vs. SPF record
The SSHFP and SPF records are both types of DNS records, but they serve very different functions. The Secure Shell Fingerprint record authenticates SSH public keys to maintain network security. In contrast, the SPF record is used to protect the reputation of a domain name by listing authorized sources. The SSHFP record stores a cryptographic fingerprint of an SSH public key, while the SPF record assigns trustworthiness to IP addresses.
Suggested article: Whitelisting vs Blacklisting, preventing or reacting
SSHFP record vs. CNAME record
The difference between an SSHFP and a DNS CNAME record is that the Secure Shell Fingerprint record stores a cryptographic fingerprint of an SSH public key and is used to authenticate the validity of the key securely. In contrast, the DNS CNAME record contains an alias or nickname associated with the server or host.
Conclusion
In summary, an SSHFP record is a beneficial DNS resource record that helps securely authenticate an SSH public key, thereby providing heightened security and trust when connecting hosts. Setting up an Secure Shell Fingerprint record is easy, and the benefits far outweigh any potential difficulties. By creating an SSHFP record for each server or host, it’s possible to quickly and securely verify the validity of a server or host’s public key, reducing the risk of man-in-the-middle attacks. If you’re considering using SSHFP records, our blog post can help you to get started.