We’ve recently moved to a semi-outsourced Exchange farm, replacing our internal one. An application I’ve been asked to help troubleshoot uses IMAP to download some emails from the Exchange servers in question. This fails. Attempting to “speak the protocol” directly (e.g., with CAPABILITY) produces custom messages about only STARTTLS being allowed (I know they are … Read more
I have some unexpected handling of RFC2047 “From” headers on Exim. (Actual addresses have been changed, the original display name contained non-ASCII characters) For this “From” header: From: =?iso-8859-1?Q?Doe=2C_John?= <john@doe.com> Which decodes to From: Doe, John <john@doe.com> The intended equivalent format likely is: From: “Doe, John” <john@doe.com> Exim populates ${addresses:$h_from:} with Doe:john@doe.com, which seems to … Read more
RFC 1553 (DHCP Options) states: 3.2. End Option The end option marks the end of valid information in the vendor field. Subsequent octets should be filled with pad options. The code for the end option is 255, and its length is 1 octet. Code +—–+ | 255 | +—–+ https://www.rfc-editor.org/rfc/rfc1533#page-2 What does it mean to … Read more
I am reading RFC5077, and bumped into following diagram: ClientHello (empty SessionTicket extension)——–> ServerHello (empty SessionTicket extension) Certificate* ServerKeyExchange* CertificateRequest* <——– ServerHelloDone Certificate* ClientKeyExchange CertificateVerify* [ChangeCipherSpec] Finished ——–> NewSessionTicket [ChangeCipherSpec] <——– Finished Application Data <——-> Application Data I guess Certificate* means there can be one or more Certificate, and [ChangeCipherSpec] means it is optional. But … Read more
As described in Section 18.2. – Client Behavior of DHCP – RFC 8415 a client uses the Solicit message to discover DHCP servers configured to assign leases or return other configuration parameters on the link to which the client is attached. As part of the Solicit message a client uses IA_NA (Identity Association for Non-temporary … Read more
From RFC 3912: 3. Protocol Example If one places a request of the WHOIS server located at whois.nic.mil for information about “Smith”, the packets on the wire will look like: client server at whois.nic.mil open TCP —- (SYN) ——————————> <—- (SYN+ACK) ————————- send query —- “Smith<CR><LF>” ——————–> get answer <—- “Info about Smith<CR><LF>” ——— <—- … Read more
Please don’t bother reading this question. syslog-ng is already set up to send RFC5424 messages with octet-counting framing by default. I was confused by the behaviour of another component. This question is invalid. I have a syslog-ng OSE config (v3.31.2): @version: 3.29 @include “scl.conf” source s_network { udp(ip(0.0.0.0) port(514)); }; destination d_network_telegraf { syslog(“telegraf” port(601) … Read more
I’ve built an open source implementation of RFC2544 to test IPv4 network devices. One of the first devices I tested is a wireless router D-Link 2640B. In order to measure its performance I use a laptop with a 10/100 Mb Ethernet interface and an integrated wireless network adapter. The traffic flow is generated by the … Read more
From https://www.rfc-editor.org/rfc/rfc3207: A publicly-referenced SMTP server MUST NOT require use of the STARTTLS extension in order to deliver mail locally. This rule (1.) prevents the STARTTLS extension from damaging the interoperability of the Internet’s SMTP infrastructure. A publicly-referenced SMTP server is an SMTP server which runs on port 25 of an Internet host listed in … Read more
Good morning, https://www.rfc-editor.org/rfc/rfc6376#section-5 reads: “Survivability of signatures after transit is not guaranteed, and signatures can fail to verify through no fault of the Signer. Therefore, a Verifier SHOULD NOT treat a message that has one or more bad signatures and no good signatures differently from a message with no signature at all.” What does that … Read more
