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How Mathematics Created Civilisation: Bestselling science writer Michael Brooks takes us on a fascinating journey through the history of civilisation, as he explains why maths is fundamental to our understanding of the world.
1 001 WEB
The World Environment Day, celebrated annually since 1972, has grown to become one of the main vehicles through which the United Nations stimulates worldwide awareness of the environment and encourages political attention and action.
Ibn Sina, or Avicenna, lived in Hamadan and Jurjan from 980 to 1037 CE, and acquired great fame in mediaeval European medicine. His encyclopaedic book Al Qanun Fi Al-Tibb (The Canon of Medicine) was translated into Latin at the end of the 12th century CE, and became a reference source for medical studies in the universities of Europe for 500 years!
From a simple cold to a serious illness, humans have always lived with the risk of catching diseases from one another. Pandemics affecting millions are fortunately rare, but the bubonic plague of the 14th century and the 1918 influenza outbreak have left a dark shadow on history.
We started in 1989 with the first store in Sydney south west and we have grown with a network of 18 physical stores in NSW and VIC, Australia. We have now been growing online to assist with possible eye care and the widest range of glasses, sunglasses, contact lenses and optical services. Our goal is to make your life easier when it comes to ocular health and maintaining your eyewear. Since the beginning, we have always seen the need for higher quality eyewear and eye care at reasonable prices. We aim to achieve this consistently during our journey as a group of professional optometrists and eyewear experts in Australia.
DHS acknowledges that there is a significant constraint around disabling 3DES in mail environments. As a result, the Department issued a temporary policy exception on this requirement on September 20, 2018.
When enabled by a receiving mail server, STARTTLS signals to a sending mail server that the capability to encrypt an email in transit is present. While it does not force the use of encryption, enabling STARTTLS makes passive man-in-the-middle attacks more difficult.
Hypertext Transfer Protocol (HTTP) connections can be easily monitored, modified, and impersonated; HTTPS remedies each vulnerability. HTTP Strict Transport Security (HSTS) ensures that browsers always use an https:// connection, and removes the ability for users to click through certificate-related warnings.
In 2015, OMB M-15-13 required all existing Federal websites and web services to be accessible through a secure connection (HTTPS-only, with HSTS). In 2017, the .gov registry began automatically preloading new federal .gov domains as HSTS-only in modern browsers.
DHS understands that compliance with this BOD could result in budgetary implications. Agency Chief Information Officers (CIOs) and procurement officers should coordinate with the agency Chief Financial Officer (CFO), as appropriate.
The Department of Homeland Security seeks to incentivize the thoughtful deployment of email authentication technologies and generally increase the security of messages to and from government agencies. Email that fraudulently uses a Federal domain should be easy to detect.
Once set, a receiver authenticates a piece of mail by comparing the IP address of the sending email server against the addresses listed on the SPF record. The SPF record is found by querying at the domain used in the email address asserted at the initial SMTP transaction, called the RFC5321.From address, or envelope From: address (among other names). If the IP address of the sender is listed in the SPF record, the message is considered authentic.
DKIM, or DomainKeys Identified Mail, involves the cryptographic signing of individual email messages. A receiver authenticates a piece of DKIM-signed mail by using the public key posted at the domain given in the DKIM header and comparing the signature embedded in the header with one the receiver calculates. If the signatures match, the message is considered authentic.
DMARC also enables a sending domain to request that participating email providers send it automatically generated reports about authentication results, thereby enabling the sending domain to monitor whether its SPF and DKIM policies are working properly.
DMARC reports are summaries of email authentication results that are automatically sent by participating email providers. They detail what the email provider saw from your domain over a given period of time, and facilitate the process of graduating to p=reject.
Both reports provide information like the sending and receiving email domains, the DMARC policy that the email recipient discovered and applied, the identifier that was evaluated by SPF and/or DKIM and whether it was in alignment, the number of successful authentications, and the totals for all messages received. Aggregate reports are normally delivered once daily from mail receivers, whereas failure reports are sent immediately after an authentication failure. Failure reports include additional information about identity alignment, and can even include much of the body of the email and email headers; this can lead to an unintended exposure of private information. Failure reports are only sent by a handful of ISPs, none of which are US-based.
The directive also requires that agencies identify and provide a list to DHS of agency second-level domains that can be HSTS preloaded. Agencies should review their list of second-level domains (including any not yet using the .gov top-level domain, as required by M-17-06) and analyze which can be preloaded.
Preloading a domain enforces the use of HTTPS across an entire zone, and is technical compliance with the HTTPS usage requirements of BOD 18-01. Preloading allows agencies to avoid inventorying and configuring an HSTS policy for every individual subdomain, though this necessarily impacts all subdomains present on the domain, including intranet subdomains. Thus, all subdomains will need to support HTTPS in order to remain reachable for use in major browsers. Even with these two obstructions, preloading a domain can be a reality with coordinated effort.
Second-level .gov domains that are only used to redirect visitors to other websites and are not used on intranets are excellent preloading candidates. However, DHS strongly recommends that federal agencies perform a thorough evaluation of those domains that are highly trafficked or otherwise have significant value. Those are likely to be the domains that citizens and intra-agency users stand to benefit most from the always-HTTPS approach that preloading provides.
For all second-level domains and all mail-sending hosts generally, make a plan to implement SPF, DKIM (mail-senders only), and DMARC, with a goal of setting p=reject on all second-level domains.
DMARC was developed to enable cautious deployment. While the standard has three policy states (none, quarantine, and reject), it also has a pct, or percent, option that a domain owner can use to tell recipients what volume of messages should have the policy applied. When pct is left unspecified, the default value of 100% is used.
No. Having legitimate email inadvertently filtered is a common concern for any organization employing traditional spam-filtering technologies. DMARC is fundamentally different from spam-filtering in how it protects from malicious email, however.
DMARC protects a domain from being impersonated without detection. It allows a domain owner to specify the authentication requirements for any email that uses their domain name, and tells a receiving email server what to do if the message fails to authenticate properly.
Subdomains can have their own p= policy set (e.g., at _dmarc.subdomain.domain.gov), but otherwise they inherit the p= policy set at the second-level domain or, if present, the subdomain policy (sp=) at the second-level domain.
Setting p=reject at the second-level domain is intended by the Directive so as to cascade throughout the zone, protecting all subdomains against spoofing. This is thwarted, though, when a policy weaker than p=reject is set on any subdomain directly or via ansp= tag set on a second-level domain.
While you work to properly authenticate email sent from subdomains, it is reasonable to set weaker-than-reject p= policies on subdomains or by setting an sp= on second-level domains. However, at one year after BOD issuance, the second-level domain must be at p=reject with no sp= policies set at the second-level domain nor subdomains with explicit policies less restrictive than reject.
Even if you do not send mail from your domain, anyone can spoof it to give the appearance that mail is coming from you. Setting a DMARC policy of p=reject signals to recipient mail servers to reject any email purportedly sent from the domain, protecting your reputation and your stakeholders from likely malicious actors.
This DMARC record has a policy of none and requests that DMARC aggregate reports be sent to reports@example.gov. These reports, as well as failure reports, should be utilized to assist in the process of getting to p=reject.
When crafting this portion of the DMARC record, take care that a) only one rua= is defined, b) each address has its own mailto:, and c) email addresses are separated by a comma. The rua portion of the DMARC policy record could look like the following:
You should also note that while receivers must support the ability to send to at least two reporting addresses, a limit can be imposed beyond two. See RFC 7489, section 6.2, or an example at appendix B.2.4.
We recommend that you first determine the most critical services that you know send on your behalf (e.g., your primary MX, alerts and monitoring, payroll/HR systems, invoicing, etc.), and ensure they are properly authenticated. After that, you can work to investigate which of the emails that are failing DMARC have actually been authorized by your organization, and proceed to authenticate with SPF/DKIM and align with DMARC. 041b061a72