Using MTA-STS to enhance email transport security and privacy

Overview SMTP is broken by design. It comes from a time when communication partners trusted each other and the NSA was intercepting facsimiles and phone calls instead of internet traffic. To enhance privacy, in 2002 RFC 3208 was added to the SMTP protocol. Unfortunately STARTTLS is only optional, it is not allowed to only accept encrypted connections. The RFC states: A publicly-referenced SMTP server MUST NOT require use of the STARTTLS extension in order to deliver mail locally. That is ….Read More

Using Unbound for recursive DNS lookup

Some organizations decide to use its internal authoritative DNS servers as recursive DNS because of easiness and reverse lookup of internal RFC 1918 networks works out of the box. That should be avoided for (at least) two reasons: Cache poisoning can cause security nightmares Authoritative answers are never cached and can cause a high load on the DNS servers. Cache poisoning is a problem that can lead to severe problems, as more and more information is stored in DNS. Examples: ….Read More

Providing SRV and TXT records for Kerberos and LDAP with dnsmasq

What if you have an application such as OVirt/RHEV-M that relies on DNS services records and you dont have the possibility to add them to the DNS servers because the DNS admins do not like to do its job? Fake them! DNSMasq is your friend 🙂 Install dnsmasq on the server in question and configure /etc/resolv.conf to query first dnsmask on localhost. yum -y install dnsmasq chkconfig dnsmasq on Assuming your subdomain is called example.com and your ldap and kerberos ….Read More