# DNSSEC ZSK Key Rollover

One important maintenance requirement for DNSSEC is the key rollover of the zone signing key (ZSK). With this procedure a new public/private key pair is used for signing the resource records, of course without any problems for the end user, i.e., no falsified signatures, etc.

In fact it is really simply to rollover the ZSK with BIND. It is almost one single CLI command to generate a new key with certain time ranges. BIND will use the correct keys at the appropriate time automatically. Here we go:

# F5 SSL Profile: “Single DH use” not working?

In the paper of the Logjam attack, a sentence about the F5 load balancers confused me a bit: “The F5 BIG-IP load balancers and hardware TLS frontends will reuse $g^{b}$ unless the “Single DH” option is checked.” This sounds like “it does NOT use a fresh/ephemeral diffie-hellman key for new connections”. I always believed, that when a cipher suite with EDH/DHE is chosen, the diffie-hellman key exchange always generates a new $b$ for computing $g^{b}$. Hm.

Therefore, I tested this “Single DH use” option on my lab F5 unit, in order to find out whether the same public key (as noted in Wireshark) is used for more than one session.