Showing posts from July, 2018

You can't add both CNAME and TXT to the same subdomain

I was a bit surprised to learn about this while processing the request of a customer. Here is the reason why "If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different. This rule also insures that a cached CNAME can be used without checking with an authoritative server for other RR types." REFERENCES

Deploy your own mail hosting with Mail-in-a-Box

Mail-in-a-Box lets you become your own mail service provider in a few easy steps. It’s sort of like making your own gmail, but one you control from top to bottom. Technically, Mail-in-a-Box turns a fresh cloud computer into a working mail server. But you don’t need to be a technology expert to set it up. The box also includes: automatic DNS configuration,  spam filtering, greylisting ,  backups to Amazon S3,  static website hosting,  and free TLS (SSL) certificates from  Let’s Encrypt . Your box can host mail for multiple users and multiple domain names. It implements modern mail protocols ( SPF ,  DKIM , and  DMARC ) and the latest security best practices, including  opportunistic TLS , strong ciphers, and  HSTS . When enabled,  DNSSEC  (with  DANE TLSA ) provides a higher level of protection against active attacks. Exchange ActiveSync is also available as a beta feature. It has web based interface for administration and features RoundCube webmail as client. Rea

What is SELinux

SELinux is a security enhancement to Linux which allows users and administrators more control over access control. Access can be constrained on such variables as which users and applications can access which resources. These resources may take the form of files. Standard Linux access controls, such as file modes (-rwxr-xr-x) are modifiable by the user and the applications which the user runs. Conversely, SELinux access controls are determined by a policy loaded on the system which may not be changed by careless users or misbehaving applications. SELinux also adds finer granularity to access controls. Instead of only being able to specify who can read, write or execute a file, for example, SELinux lets you specify who can unlink, append only, move a file and so on. SELinux allows you to specifby access to many resources other than files as well, such as network resources and interprocess communication (IPC). Reference :