27 votes

What's the point of repeating an email address in "The Envelope" and the "The Header"?

The addresses in an email message header serve different purposes than the envelope sender and recipient (which really aren't hidden per se, they just aren't part of the message). The envelope sender ...
Michael Hampton's user avatar
16 votes
Accepted

RFC that requires DNS servers to respond to unknown domain requests

Shane's advice is correct. Failure to migrate data from one authoritative server to another prior to initiating a cutover is an invitation for an outage. Regardless of what happens from that point ...
Andrew B's user avatar
  • 33.1k
13 votes

What's the point of repeating an email address in "The Envelope" and the "The Header"?

The most common scenario where you will see a difference is during delivery of an email with multiple recipients. Let's say you are about to send an email to: [email protected] [email protected] b@example....
kasperd's user avatar
  • 30.7k
4 votes

Can nginx use different SSL protocols in different server blocks?

This seems to be a bug in nginx. I just had this now, took me a while to figure it out. It's always only using the ssl_protocols directive from the first server block. In my case I have many virtual ...
peedee's user avatar
  • 451
4 votes

SSH without invoking shell

[for the record only -- at the time of writing, the problem has long been fixed, hopefully] With openssh, ANY command executed by sshd is executed via your login shell with the -c option: command ...
xhienne's user avatar
  • 188
4 votes
Accepted

tcpdump - prevent interpreting/decoding protocols

You can use the '-q' option to remove the content decoding. You can maybe add the '-A' to see in ASCII the content of the packets, or -dd to see in C format.
Dom's user avatar
  • 6,793
3 votes

Listener Protocol for ELB in front of Squid Proxy

I suppose you want to change your ELB to use HTTP, since you want to log the client IP address. You have 2 options to achieve this - 1. Use your ELB with TCP (and NOT HTTP), and configure it to ...
Gilad Sharaby's user avatar
3 votes

Listener Protocol for ELB in front of Squid Proxy

I suspect they want to get at the X-Forwarded-For original IP of the requestor for the logs. I know I am. ELBs don't forward these headers when using TCP in the ELB, but if you set to HTTP/3128 ...
Steve's user avatar
  • 31
3 votes

RFC that requires DNS servers to respond to unknown domain requests

When you're moving authoritative DNS for a domain to a new provider, you should always (always!) test explicitly against the new provider (and ensure they're sending accurate, configured records) ...
Shane Madden's user avatar
3 votes

Is RFC 7231 the latest version about the HTTP/1.1 protocol?

HTTP/1.1 is officially described by 6 RFCs: RFC 7230, HTTP/1.1: Message Syntax Routing RFC 7231, HTTP/1.1: Semantics and Content RFC 7232, HTTP/1.1: Conditional Requests RFC 7233, HTTP/1.1: Range ...
Barry Pollard's user avatar
2 votes
Accepted

Why does OpenSSH on Macos look for known hosts file twice?

When UpdateHostKeys is enabled, after user is authenticated, it will be verified if there are host keys to be updated in ~/.ssh/known_hosts. So for the first time ~/.ssh/known_hosts is read during ...
petee's user avatar
  • 46
2 votes

Apparent inconsistency in Apache SSLProtocol

Further experimentation has yielded the answer. The configuration: SSLProtocol TLSv1.2 TLSv1.3 is taken by Apache 2.4 to mean support for only TLSv1.3. It seems that if more than one protocol is ...
mbrampton's user avatar
  • 361
1 vote

Do ports change for every request? Are Ip ports are different from system ports?

A typical ip address has >65k No. The IP protocol understands 65536 possible ports (it is a 2 byte identigier) which is exactly 64x1024, and computers are base 2. Also, a connection is not ...
TomTom's user avatar
  • 51.9k
1 vote

Is RFC 7231 the latest version about the HTTP/1.1 protocol?

It must be, as it doesn't show that it's been updated by another RFC, like in the example below for RFC 2821. Whereas RFC 7231 shows no such Updated by:
joeqwerty's user avatar
  • 111k
1 vote

TCP protocol strange behaviour in my program

I solved the problem putting a delay of 300ms before closing Streand and the Socket so the Client and Server has the right time to talk each other. Lower delay make them unsynch again! May this post ...
user3649959's user avatar
1 vote

Can nginx use different SSL protocols in different server blocks?

IMHO, this is a bug in nginx - the Client Hello packet contains the SNI which can be extracted to find the virtual server block before responding with the server hello and the list of supported TLS ...
Bhakta Raghavan's user avatar

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