SSHFP
All persons authorized for the DNS-Admin can now store so-called Secure Shell Fingerprints (SSHFP) in the DNS via individual entries or a mass import (see RFC 4255, 6594 and 7479. The structure of this record type (for detailed parameters see iana.org) is:
<$SERVER.$DOMAIN.rwth-aachen.de.> [<TTL in seconds>] [<Class>] SSHFP <number of the algorithm> <number of the hash type> <hexadecimal fingerprint> |
Information on algorithm and hash type
- Generate SSHFP
on the server
sudo ssh-keygen -r $HOSTNAME.$DOMAIN.rwth-aachen.de.remote(via grabsshfp.sh)
/grabsshfp.sh $HOSTNAME.$DOMAIN.rwth-aachen.de.
- Consider SSHFP when establishing a connection
per request
ssh -o VerifyHostKeyDNS=yes -l $USER $HOSTNAME.$DOMAIN.rwth-aachen.de.ssh -o FingerprintHash=sha256 -o VerifyHostKeyDNS=yes -l $USER $HOSTNAME.$DOMAIN.rwth-aachen.de.gloabe SSH Client Configuration (all SSH connections from one computer, see "Hostname canonicalisation in OpenSSH)
/etc/ssh/ssh_configCanonicalizeHostname yesCanonicalDomains $DOMAIN.rwth-aachen.deCanonicalizeMaxDots 0CanonicalizeFallbackLocal noVerifyHostKeyDNS yes