RFC 2249
Mail Monitoring MIB
Mail Monitoring MIB 🎀
RFC 2249 💖 by N. Freed (Innosoft) and S. Kille (ISODE Consortium) ✨
- Category: Standards Track 🔥
- Date: January 1998 🌸
- Obsoletes: RFC 1566 💅
Okay bestie, so this is the doc that defines a Mail Monitoring MIB, and it's the sequel to RFC 1566. It's an Internet standards track protocol spec, so it's giving official, important energy 👑
Status of this Memo 🦋
This document is an Internet standards track protocol for the Internet community. It asks for discussion and suggestions for improvements 💜 For the current standardization state and status of this protocol, check the "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited 🌈
Copyright Notice 🌸
Copyright (C) The Internet Society (1998). All Rights Reserved. 💅
1. Introduction ✨
Okay so this memo defines a chunk of the Management Information Base (MIB) for network management protocols in the Internet community. 🧚 The main thing is that it extends the basic Network Services Monitoring MIB [8] so you can monitor Message Transfer Agents (MTAs) 💖 It can also be used to monitor MTA components inside gateways 🫶
2. Table of Contents 📋
1 Introduction ............................................. 1
2 Table of Contents ........................................ 1
3 The SNMPv2 Network Management Framework .................. 2
3.1 Object Definitions ..................................... 2
4 Message Flow Model ....................................... 2
5 MTA Objects .............................................. 3
6 Definitions .............................................. 4
7 Changes made since RFC 1566 .............................. 25
8 Acknowledgements ......................................... 26
9 References ............................................... 26
10 Security Considerations ................................. 27
11 Author and Chair Addresses .............................. 27
12 Full Copyright Statement ................................ 283. The SNMPv2 Network Management Framework 🍓
The SNMPv2 Network Management Framework is made of seven major components. Here they are:
- RFC 1902 [1] defines the SMI, which is the mechanisms used for describing and naming objects for management purposes 🎀
- RFC 1903 [2] defines textual conventions for SNMPv2 ✨
- RFC 1904 [3] defines conformance statements for SNMPv2 💅
- RFC 1905 [4] defines transport mappings for SNMPv2 🦋
- RFC 1906 [5] defines the protocol operations used for network access to managed objects 🔥
- RFC 1907 [6] defines the Management Information Base for SNMPv2 🌈
- RFC 1908 [7] specifies coexistence between SNMP and SNMPv2 🫶
The Framework lets new objects be defined for experimentation and evaluation, so it's giving room to play 🧪💜
3.1. Object Definitions 🧚
Managed objects are accessed through a virtual information store, called the Management Information Base or MIB 💖 Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) that the SMI defines 🌸 The key thing is that each object type is named by an OBJECT IDENTIFIER, which is an administratively assigned name ✨ The object type together with an object instance uniquely identifies one specific instantiation of the object 👑 For human convenience, we often use a textual string, called the descriptor, to refer to the object type 🙈
4. Message Flow Model 💌
Before we can describe a MIB, we have to present a general model of message flow inside an MTA. Generally speaking, message flow is modelled as happening in four steps 🔥
- Messages are received by the MTA from User Agents, Message Stores, other MTAs, and gateways 📥
- The "next hop" for each message is determined. This is simply the destination the message is to be transmitted to, and it may or may not be the final destination of the message 🦋
Multiple "next hops" may exist for a single message (because it has multiple recipients or a distribution list gets expanded). This may make it necessary to duplicate messages 👯♀️
- If necessary, messages are converted into the format that's appropriate for the next hop. Conversion operations may be successful or unsuccessful 🎀
- Messages are transmitted to the appropriate destination, which may be a User Agent, Message Store, another MTA, or gateway 🚀
Storage of messages in the MTA happens at some point during this process 🌈 But here's the tea: storage may occur at different, and possibly even multiple, points during the process 💅 For example, some MTAs expand messages into multiple copies as they are received. In that case (1), (2), and (3) may all happen before storage ✨ Other MTAs store messages exactly as they are received and do all expansions and conversions during retransmission processing. So only (1) happens before storage here 🙈
This leads to situations where, in general, a measurement of messages received may not equal a measurement of messages in store. Or a measurement of messages stored may not equal a measurement of messages retransmitted. Or both 😭💀
5. MTA Objects 🧁
If there are one or more MTAs on the host, you can use the following MIB to monitor them 🫶 You can monitor any number of MTAs on a single host or a group of hosts ✨ Each MTA is handled as a separate network service and has its own applTable entry in the Network Services Monitoring MIB 💜
The MIB described in this document only covers the part that's specific to monitoring MTAs. The network service related part of the MIB is covered in a separate document [8] 🦋
This MIB defines four tables, and here's how they slay 👑
- The first table holds per-MTA information that isn't specific to any particular part of the MTA 🌸
- The second table breaks each MTA down into a collection of separate components called groups. Groups are described in detail in the comments embedded in the MIB below 🧚
- The third table correlates associations tracked by the network services MIB with specific groups within different MTAs 🔗
- The fourth table tracks any errors encountered during the operation of the MTA 🙈
The first two tables must be implemented to conform with this MIB. The last two are optional 🎀
6. Definitions 💻
MTA-MIB DEFINITIONS ::= BEGIN
IMPORTS
OBJECT-TYPE, Counter32, Gauge32, MODULE-IDENTITY, mib-2
FROM SNMPv2-SMI
DisplayString, TimeInterval
FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP
FROM SNMPv2-CONF
applIndex, URLString
FROM NETWORK-SERVICES-MIB;
mta MODULE-IDENTITY
LAST-UPDATED "9708170000Z"
ORGANIZATION "IETF Mail and Directory Management Working Group"
CONTACT-INFO
" Ned Freed
Postal: Innosoft International, Inc.
1050 Lakes Drive
West Covina, CA 91790
US
Tel: +1 626 919 3600
Fax: +1 626 919 3614
E-Mail: ned.freed@innosoft.com"
DESCRIPTION
"The MIB module describing Message Transfer Agents (MTAs)"
REVISION "9311280000Z"
DESCRIPTION
"The original version of this MIB was published in RFC 1566"
::= {mib-2 28}
mtaTable OBJECT-TYPE
SYNTAX SEQUENCE OF MtaEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table holding information specific to an MTA."
::= {mta 1}
mtaStatusCode OBJECT-TYPE
SYNTAX INTEGER (4000000..5999999)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An index capable of representing an Enhanced Mail System
Status Code. Enhanced Mail System Status Codes are
defined in RFC 1893 [14]. These codes have the form
class.subject.detail
Here 'class' is either 2, 4, or 5 and both 'subject' and
'detail' are integers in the range 0..999. Given a status
code the corresponding index value is defined to be
((class * 1000) + subject) * 1000 + detail. Both SMTP
error response codes and X.400 reason and diagnostic codes
can be mapped into these codes, resulting in a namespace
capable of describing most error conditions a mail system
encounters in a generic yet detailed way."
::= {mta 6}
mtaEntry OBJECT-TYPE
SYNTAX MtaEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The entry associated with each MTA."
INDEX {applIndex}
::= {mtaTable 1}
MtaEntry ::= SEQUENCE {
mtaReceivedMessages
Counter32,
mtaStoredMessages
Gauge32,
mtaTransmittedMessages
Counter32,
mtaReceivedVolume
Counter32,
mtaStoredVolume
Gauge32,
mtaTransmittedVolume
Counter32,
mtaReceivedRecipients
Counter32,
mtaStoredRecipients
Gauge32,
mtaTransmittedRecipients
Counter32,
mtaSuccessfulConvertedMessages
Counter32,
mtaFailedConvertedMessages
Counter32,
mtaLoopsDetected
Counter32
}
mtaReceivedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages received since MTA initialization.
This includes messages transmitted to this MTA from other
MTAs as well as messages that have been submitted to the
MTA directly by end-users or applications."
::= {mtaEntry 1}
mtaStoredMessages OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of messages currently stored in the MTA.
This includes messages that are awaiting transmission to
some other MTA or are waiting for delivery to an end-user
or application."
::= {mtaEntry 2}
mtaTransmittedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages transmitted since MTA initialization.
This includes messages that were transmitted to some other
MTA or are waiting for delivery to an end-user or
application."
::= {mtaEntry 3}
mtaReceivedVolume OBJECT-TYPE
SYNTAX Counter32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages received since MTA
initialization, measured in kilo-octets. This volume should
include all transferred data that is logically above the mail
transport protocol level. For example, an SMTP-based MTA
should use the number of kilo-octets in the message header
and body, while an X.400-based MTA should use the number of
kilo-octets of P2 data. This includes messages transmitted
to this MTA from other MTAs as well as messages that have
been submitted to the MTA directly by end-users or
applications."
::= {mtaEntry 4}
mtaStoredVolume OBJECT-TYPE
SYNTAX Gauge32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages currently stored in the MTA,
measured in kilo-octets. This volume should include all
stored data that is logically above the mail transport
protocol level. For example, an SMTP-based MTA should
use the number of kilo-octets in the message header and
body, while an X.400-based MTA would use the number of
kilo-octets of P2 data. This includes messages that are
awaiting transmission to some other MTA or are waiting
for delivery to an end-user or application."
::= {mtaEntry 5}Okay bestie, so this is where the MIB starts counting everything 💖 Transmitted volume, recipients in and out, conversions, and loop detection 🌈 all live in mtaEntry, then the group stuff kicks in with its own table, so grab a snack 🍓
mtaTransmittedVolume OBJECT-TYPE
SYNTAX Counter32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages transmitted since MTA
initialization, measured in kilo-octets. This volume should
include all transferred data that is logically above the mail
transport protocol level. For example, an SMTP-based MTA
should use the number of kilo-octets in the message header
and body, while an X.400-based MTA should use the number of
kilo-octets of P2 data. This includes messages that were
transmitted to some other MTA or are waiting for delivery
to an end-user or application."
::= {mtaEntry 6}
mtaReceivedRecipients OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
received since MTA initialization. Recipients this MTA
has no responsibility for, i.e. inactive envelope
recipients or ones referred to in message headers,
should not be counted even if information about such
recipients is available. This includes messages
transmitted to this MTA from other MTAs as well as
messages that have been submitted to the MTA directly
by end-users or applications."
::= {mtaEntry 7}
mtaStoredRecipients OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
currently stored in the MTA. Recipients this MTA has no
responsibility for, i.e. inactive envelope recipients or
ones referred to in message headers, should not be
counted. This includes messages that are awaiting
transmission to some other MTA or are waiting for
delivery to an end-user or application."
::= {mtaEntry 8}
mtaTransmittedRecipients OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
transmitted since MTA initialization. Recipients this
MTA had no responsibility for, i.e. inactive envelope
recipients or ones referred to in message headers,
should not be counted. This includes messages that were
transmitted to some other MTA or are waiting for
delivery to an end-user or application."
::= {mtaEntry 9}
mtaSuccessfulConvertedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages that have been successfully
converted from one form to another since MTA
initialization."
::= {mtaEntry 10}
mtaFailedConvertedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages for which an unsuccessful
attempt was made to convert them from one form to
another since MTA initialization."
::= {mtaEntry 11}
mtaLoopsDetected OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A message loop is defined as a situation where the MTA
decides that a given message will never be delivered to
one or more recipients and instead will continue to
loop endlessly through one or more MTAs. This variable
counts the number of times the MTA has detected such a
situation since MTA initialization. Note that the
mechanism MTAs use to detect loops (e.g. trace field
counting, count of references to this MTA in a trace
field, examination of DNS or other directory information,
etc.), the level at which loops are detected (e.g. per
message, per recipient, per directory entry, etc.), and
the handling of a loop once it is detected (e.g. looping
messages are held, looping messages are bounced or sent
to the postmaster, messages that the MTA knows will loop
won't be accepted, etc.) vary widely from one MTA to the
next and cannot be inferred from this variable."
::= {mtaEntry 12}
-- MTAs typically group inbound reception, queue storage, and
-- outbound transmission in some way, rather than accounting for
-- such operations only across the MTA as a whole. In the most
-- extreme case separate information will be maintained for each
-- different entity that receives messages and for each entity
-- the MTA stores messages for and delivers messages to. Other
-- MTAs may elect to treat all reception equally, all queue
-- storage equally, all deliveries equally, or some combination
-- of this. Overlapped groupings are also possible, where an MTA
-- decomposes its traffic in different ways for different
-- purposes.
-- In any case, a grouping abstraction is an extremely useful for
-- breaking down the activities of an MTA. For purposes of
-- labelling this will be called a "group" in this MIB.
-- Each group contains all the variables needed to monitor all
-- aspects of an MTA's operation. However, the fact that all
-- groups contain all possible variables does not imply that all
-- groups must use all possible variables. For example, a single
-- group might be used to monitor only one kind of event (inbound
-- processing, outbound processing, or storage). In this sort of
-- configuration all unused counters would be inaccessible; e.g.,
-- returning either a noSuchName error (for an SNMPv1 get), or a
-- noSuchInstance exception (for an SNMPv2 get).
-- Groups can be created at any time after MTA initialization. Once
-- a group is created it should not be deleted or its mtaGroupIndex
-- changed unless the MTA is reinitialized.
-- Groups are not necessarily mutually exclusive. A given event may
-- be recorded by more than one group, a message may be seen as
-- stored by more than one group, and so on. Groups should be all
-- inclusive, however: if groups are implemented all aspects of an
-- MTA's operation should be registered in at least one group. This
-- freedom lets implementors use different sets of groups to
-- provide differents "views" of an MTA.
-- The possibility of overlap between groups means that summing
-- variables across groups may not produce values equal to those in
-- the mtaTable. mtaTable should always provide accurate information
-- about the MTA as a whole.
-- The term "channel" is often used in MTA implementations; channels
-- are usually, but not always, equivalent to a group. However,
-- this MIB does not use the term "channel" because there is no
-- requirement that an MTA supporting this MIB has to map its
-- "channel" abstraction one-to-one onto the MIB's group abstration.
-- An MTA may create a group or group of groups at any time. Once
-- created, however, an MTA cannot delete an entry for a group from
-- the group table. Deletation is only allowed when the MTA is
-- reinitialized, and is not required even then. This restriction
-- is imposed so that monitoring agents can rely on group
-- assignments being consistent across multiple query operations.
-- Groups may be laid out so as to form a hierarchical arrangement,
-- with some groups acting as subgroups for other groups.
-- Alternately, disjoint groups of groups may be used to provide
-- different sorts of "snapshots" of MTA operation. The
-- mtaGroupHierarchy variable provides an indication of how each
-- group fits into the overall arrangement being used.
mtaGroupTable OBJECT-TYPE
SYNTAX SEQUENCE OF MtaGroupEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table holding information specific to each MTA group."
::= {mta 2}
mtaGroupEntry OBJECT-TYPE
SYNTAX MtaGroupEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The entry associated with each MTA group."
INDEX {applIndex, mtaGroupIndex}
::= {mtaGroupTable 1}
MtaGroupEntry ::= SEQUENCE {
mtaGroupIndex
INTEGER,
mtaGroupReceivedMessages
Counter32,
mtaGroupRejectedMessages
Counter32,
mtaGroupStoredMessages
Gauge32,
mtaGroupTransmittedMessages
Counter32,
mtaGroupReceivedVolume
Counter32,
mtaGroupStoredVolume
Gauge32,
mtaGroupTransmittedVolume
Counter32,
mtaGroupReceivedRecipients
Counter32,
mtaGroupStoredRecipients
Gauge32,
mtaGroupTransmittedRecipients
Counter32,
mtaGroupOldestMessageStored
TimeInterval,
mtaGroupInboundAssociations
Gauge32,
mtaGroupOutboundAssociations
Gauge32,
mtaGroupAccumulatedInboundAssociations
Counter32,
mtaGroupAccumulatedOutboundAssociations
Counter32,
mtaGroupLastInboundActivity
TimeInterval,
mtaGroupLastOutboundActivity
TimeInterval,
mtaGroupLastOutboundAssociationAttempt
TimeInterval,
mtaGroupRejectedInboundAssociations
Counter32,
mtaGroupFailedOutboundAssociations
Counter32,
mtaGroupInboundRejectionReason
DisplayString,
mtaGroupOutboundConnectFailureReason
DisplayString,
mtaGroupScheduledRetry
TimeInterval,
mtaGroupMailProtocol
OBJECT IDENTIFIER,
mtaGroupName
DisplayString,
mtaGroupSuccessfulConvertedMessages
Counter32,
mtaGroupFailedConvertedMessages
Counter32,
mtaGroupDescription
DisplayString,
mtaGroupURL
URLString,
mtaGroupCreationTime
TimeInterval,
mtaGroupHierarchy
INTEGER,
mtaGroupOldestMessageId
DisplayString,
mtaGroupLoopsDetected
Counter32
}
mtaGroupIndex OBJECT-TYPE
SYNTAX INTEGER (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The index associated with a group for a given MTA."
::= {mtaGroupEntry 1}
mtaGroupReceivedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages received to this group since
group creation."
::= {mtaGroupEntry 2}
mtaGroupRejectedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages rejected by this group since
group creation."
::= {mtaGroupEntry 3}
mtaGroupStoredMessages OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of messages currently stored in this
group's queue."
::= {mtaGroupEntry 4}
mtaGroupTransmittedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages transmitted by this group since
group creation."
::= {mtaGroupEntry 5}
mtaGroupReceivedVolume OBJECT-TYPE
SYNTAX Counter32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages received to this group since
group creation, measured in kilo-octets. This volume
should include all transferred data that is logically above
the mail transport protocol level. For example, an
SMTP-based MTA should use the number of kilo-octets in the
message header and body, while an X.400-based MTA should use
the number of kilo-octets of P2 data."
::= {mtaGroupEntry 6}okay bestie, we're still in the group-stats zone and it's giving data-nerd realness 🤓💅
Next up is the storage volume counter, which tells you how much stuff is sitting in the queue right now. 📦✨
mtaGroupStoredVolume OBJECT-TYPE
SYNTAX Gauge32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages currently stored in this
group's queue, measured in kilo-octets. This volume should
include all stored data that is logically above the mail
transport protocol level. For example, an SMTP-based
MTA should use the number of kilo-octets in the message
header and body, while an X.400-based MTA would use the
number of kilo-octets of P2 data."
::= {mtaGroupEntry 7}The vibe here is "how heavy is the backlog right now?" 🎀 It's a Gauge32, so it can go up and down, and it's measured in K-octets. Also, it only counts the mail-level stuff, so SMTP folks count the header and body, and X.400 folks count their P2 data. Literally so specific, I'm obsessed 😭
mtaGroupTransmittedVolume OBJECT-TYPE
SYNTAX Counter32
UNITS "K-octets"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total volume of messages transmitted by this group
since group creation, measured in kilo-octets. This
volume should include all transferred data that is logically
above the mail transport protocol level. For example, an
SMTP-based MTA should use the number of kilo-octets in the
message header and body, while an X.400-based MTA should use
the number of kilo-octets of P2 data."
::= {mtaGroupEntry 8}Okay so this one is the transmitted version, and it's a Counter32 instead, so it only ever goes up 📈 It counts from group creation and uses the same mail-level rule as before. Same energy, different direction 🦋
mtaGroupReceivedRecipients OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
received to this group since group creation.
Recipients this MTA has no responsibility for should not
be counted."
::= {mtaGroupEntry 9}Now we're counting recipients instead of bytes 📬 This one is all the recipients on messages the group received since it was created. The big rule here is that recipients the MTA isn't responsible for should not be counted. Not me being picky, just being accurate 💖
mtaGroupStoredRecipients OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
currently stored in this group's queue. Recipients this
MTA has no responsibility for should not be counted."
::= {mtaGroupEntry 10}This is the currently stored recipient count, so it's a Gauge32 and it can drop as the queue drains 🌊 Same rule as before: no counting recipients the MTA has no responsibility for 🙅♀️
mtaGroupTransmittedRecipients OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of recipients specified in all messages
transmitted by this group since group creation.
Recipients this MTA had no responsibility for should not
be counted."
::= {mtaGroupEntry 11}And the transmitted version is the Counter32 twin of the one we just did. It counts recipients on everything the group sent since creation, with that same "no responsibility, no count" rule ✨
mtaGroupOldestMessageStored OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Time since the oldest message in this group's queue was
placed in the queue."
::= {mtaGroupEntry 12}Okay this is the "how long has the oldest message been waiting?" object ⏳ It's a TimeInterval, and it measures time since that oldest message got put in the queue. Main character waiting energy 💀
mtaGroupInboundAssociations OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of current associations to the group, where the
group is the responder."
::= {mtaGroupEntry 13}Quick association refresher: when the group is the responder, it's an inbound association 📥 This counts the ones that are active right now.
mtaGroupOutboundAssociations OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of current associations to the group, where the
group is the initiator."
::= {mtaGroupEntry 14}And this is the mirror image. When the group is the initiator, it's outbound 📤 Same idea, opposite direction 🔄
mtaGroupAccumulatedInboundAssociations OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of associations to the group since
group creation, where the MTA was the responder."
::= {mtaGroupEntry 15}Accumulated means it's the lifetime total instead of what's happening right now. This is every inbound association since the group was created, Counter32 style 🎀
mtaGroupAccumulatedOutboundAssociations OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of associations from the group since
group creation, where the MTA was the initiator."
::= {mtaGroupEntry 16}And the outbound lifetime total, same thing from the other side 🧚 Initiator, since creation, done.
mtaGroupLastInboundActivity OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Time since the last time that this group had an active
inbound association for purposes of message reception."
::= {mtaGroupEntry 17}This one tracks how long it's been since the group had an active inbound association for receiving messages 📨 Think of it as the "last seen" timestamp for incoming mail 👀
mtaGroupLastOutboundActivity OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Time since the last time that this group had a
successful outbound association for purposes of
message delivery."
::= {mtaGroupEntry 18}The outbound version is a little pickier. It only counts a successful outbound association used for delivering messages ✅ So a failed try doesn't reset this one. Lowkey important distinction 💅
mtaGroupLastOutboundAssociationAttempt OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Time since the last time that this group attempted
to make an outbound association for purposes of
message delivery."
::= {mtaGroupEntry 34}And this is the "they tried" version, not the "they succeeded" version 🙈 It counts the last attempt at an outbound association for delivery, even if it didn't work. Note that it's entry 34, not 19, because the numbering is a little out of order here 🧐
mtaGroupRejectedInboundAssociations OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of inbound associations the group has
rejected, since group creation. Rejected associations
are not counted in the accumulated association totals."
::= {mtaGroupEntry 19}Rejected inbound associations get their own counter, and they're not included in the accumulated totals from earlier. So rejects and accepted ones stay in separate lanes 🚫
mtaGroupFailedOutboundAssociations OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number associations where the group was the
initiator and association establishment has failed,
since group creation. Failed associations are
not counted in the accumulated association totals."
::= {mtaGroupEntry 20}Same deal for outbound: the group started it, the setup failed, and it gets its own count since creation. These failures also stay out of the accumulated totals 💔
mtaGroupInboundRejectionReason OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The failure reason, if any, for the last association this
group refused to respond to. An empty string indicates that
the last attempt was successful. If no association attempt
has been made since the MTA was initialized the value
should be 'never'."
::= {mtaGroupEntry 21}This one is the "why did we say no?" text for the most recent inbound association the group refused 🙅♀️ An empty string means the last attempt went through fine. And if nothing has been tried since the MTA started up, it should say 'never'. Very clear, very iconic ✨
mtaGroupOutboundConnectFailureReason OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The failure reason, if any, for the last association attempt
this group initiated. An empty string indicates that the last
attempt was successful. If no association attempt has been
made since the MTA was initialized the value should be
'never'."
::= {mtaGroupEntry 22}The outbound mirror of the one above. It's the reason the last association attempt the group started failed, with the same empty-string-means-success and 'never' rules 🌸
mtaGroupScheduledRetry OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The time when this group is scheduled to next attempt to
make an association."
::= {mtaGroupEntry 23}This is the countdown to the group's next try at making an association ⏰ It's a TimeInterval, so it's about when the next attempt is scheduled, not what happened last time.
mtaGroupMailProtocol OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An identification of the protocol being used by this group.
For an group employing OSI protocols, this will be the
Application Context. For Internet applications, the IANA
maintains a registry of the OIDs which correspond to well-known
message transfer protocols. If the application protocol is
not listed in the registry, an OID value of the form
{applTCPProtoID port} or {applUDProtoID port} are used for
TCP-based and UDP-based protocols, respectively. In either
case 'port' corresponds to the primary port number being
used by the group. applTCPProtoID and applUDPProtoID are
defined in [8]."
::= {mtaGroupEntry 24}This one is the group's protocol ID 🪪 For OSI stuff it's the Application Context. For Internet apps, there's an IANA registry of well-known OIDs. If the protocol isn't in the registry, you use {applTCPProtoID port} for TCP or {applUDPProtoID port} for UDP, where port is the group's main port. Those two are defined in [8] 📚
mtaGroupName OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A descriptive name for the group. If this group connects to
a single remote MTA this should be the name of that MTA. If
this in turn is an Internet MTA this should be the domain
name. For an OSI MTA it should be the string encoded
distinguished name of the managed object using the format
defined in RFC 1779 [9]. For X.400(1984) MTAs which do not
have a Distinguished Name, the RFC 1327 [12] syntax
'mta in globalid' should be used."
::= {mtaGroupEntry 25}The name is the group's label 🏷️ If it talks to one remote MTA, the name should be that MTA's name. If it's an Internet MTA, use the domain name. OSI MTAs use the string-encoded distinguished name per [9] (RFC 1779). X.400(1984) MTAs without a DN use the 'mta in globalid' syntax from [12] (RFC 1327). Very specific, very formal, very us 💖
mtaGroupSuccessfulConvertedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages that have been successfully
converted from one form to another in this group
since group creation."
::= {mtaGroupEntry 26}Now we're in message conversion land 🔁 This counts the messages that got converted from one form to another successfully in this group since creation. Yay for wins ✨
mtaGroupFailedConvertedMessages OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of messages for which an unsuccessful
attempt was made to convert them from one form to
another in this group since group creation."
::= {mtaGroupEntry 27}And the sad twin: messages where a conversion was attempted but didn't work 😭 Same group, same since-creation window, just the flops.
mtaGroupDescription OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A description of the group's purpose. This information is
intended to identify the group in a status display."
::= {mtaGroupEntry 28}This is the human-readable what is this group for? field 📝 It's meant to help identify the group when you're looking at a status display 🖥️
mtaGroupURL OBJECT-TYPE
SYNTAX URLString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A URL pointing to a description of the group. This
information is intended to identify and briefly describe
the group in a status display."
::= {mtaGroupEntry 29}Like the description, but it's a link 🔗 It points to a description of the group, and it's also meant for brief identification in a status display 🌈
mtaGroupCreationTime OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Time since this group was first created."
::= {mtaGroupEntry 30}This is how long ago the group was born 🎂 A TimeInterval since first creation. Old enough to have a whole personality now 💅
mtaGroupHierarchy OBJECT-TYPE
SYNTAX INTEGER (-2147483648..2147483647)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Describes how this group fits into the hierarchy. A
positive value is interpreted as an mtaGroupIndex
value for some other group whose variables include
those of this group (and usually others). A negative
value is interpreted as a group collection code: Groups
with common negative hierarchy values comprise one
particular breakdown of MTA activity as a whole. A
zero value means that this MIB implementation doesn't
implement hierarchy indicators and thus the overall
group hierarchy cannot be determined."
::= {mtaGroupEntry 31}Okay, the family tree situation 🌳 This is a signed INTEGER and it tells you where the group sits in the hierarchy. A positive value points at the mtaGroupIndex of another group whose variables include this one's (and usually more). A negative value is a group collection code, so groups sharing the same negative number make up one breakdown of MTA activity 🧩 And zero means this MIB doesn't do hierarchy indicators, so the overall hierarchy can't be figured out. Lowkey a lot of pieces, but iconic 🫶
mtaGroupOldestMessageId OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Message ID of the oldest message in the group's queue.
Whenever possible this should be in the form of an
RFC 822 [13] msg-id; X.400 may convert X.400 message
identifiers to this form by following the rules laid
out in RFC1327 [12]."
::= {mtaGroupEntry 32}This is the ID of the oldest message sitting in the queue 🆔 Whenever possible, it should look like an RFC 822 [13] msg-id. X.400 can convert its message identifiers to that form by following the rules in RFC1327 [12] 🪄
mtaGroupLoopsDetected OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A message loop is defined as a situation where the MTA
decides that a given message will never be delivered to
one or more recipients and instead will continue to
loop endlessly through one or more MTAs. This variable
counts the number of times the MTA has detected such a
situation in conjunction with something associated with
this group since group creation. Note that the
mechanism MTAs use to detect loops (e.g. trace field
counting, count of references to this MTA in a trace
field, examination of DNS or other directory information,
etc.), the level at which loops are detected (e.g. per
message, per recipient, per directory entry, etc.), and
the handling of a loop once it is detected (e.g. looping
messages are held, looping messages are bounced or sent
to the postmaster, messages that the MTA knows will loop
won't be accepted, etc.) vary widely from one MTA to the
next and cannot be inferred from this variable."
::= {mtaGroupEntry 33}Mail loops are a whole vibe 🔄💀 A message loop is when the MTA decides a message will never reach one or more recipients, but it keeps bouncing around between MTAs forever. This Counter32 counts how many times that's been detected for this group since creation. The thing to know is that how an MTA detects loops, where it detects them, and what it does about them all vary a lot from one MTA to the next, so you can't guess any of that from this number 🙅♀️
-- The mtaGroupAssociationTable provides a means of correlating
-- entries in the network services association table with the
-- MTA group responsible for the association.
mtaGroupAssociationTable OBJECT-TYPE
SYNTAX SEQUENCE OF MtaGroupAssociationEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table holding information regarding the associations
for each MTA group."
::= {mta 3}And the last bit here is the mtaGroupAssociationTable, which is the table that links the network services association entries back to the MTA group that's responsible for each one 🎀 It's not-accessible, so it's basically the backstage pass for the association data 🎟️
Okay that's the whole group-stat squad, bestie! 🌈✨
Okay bestie, we're picking up right where the association table left off 🦋✨ First up, the association entries and the whole error-tally situation, which is honestly so clever 💅
mtaGroupAssociationEntry OBJECT-TYPE
SYNTAX MtaGroupAssociationEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The entry holding information regarding the associations
for each MTA group."
INDEX {applIndex, mtaGroupIndex, mtaGroupAssociationIndex}
::= {mtaGroupAssociationTable 1}
MtaGroupAssociationEntry ::= SEQUENCE {
mtaGroupAssociationIndex
INTEGER
}
mtaGroupAssociationIndex OBJECT-TYPE
SYNTAX INTEGER (1..2147483647)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Reference into association table to allow correlation of
this group's active associations with the association table."
::= {mtaGroupAssociationEntry 1}
-- The mtaGroupErrorTable gives each group a way of tallying
-- the specific errors it has encountered. The mechanism
-- defined here uses RFC 1893 [14] status codes to identify
-- various specific errors. There are also classes for generic
-- errors of various sorts, and the entire mechanism is also
-- extensible, in that new error codes can be defined at any
-- time.
mtaGroupErrorTable OBJECT-TYPE
SYNTAX SEQUENCE OF MtaGroupErrorEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table holding information regarding accumulated errors
for each MTA group."
::= {mta 5}
mtaGroupErrorEntry OBJECT-TYPE
SYNTAX MtaGroupErrorEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The entry holding information regarding accumulated
errors for each MTA group."
INDEX {applIndex, mtaGroupIndex, mtaStatusCode}
::= {mtaGroupErrorTable 1}
MtaGroupErrorEntry ::= SEQUENCE {
mtaGroupInboundErrorCount
Counter32,
mtaGroupInternalErrorCount
Counter32,
mtaGroupOutboundErrorCount
Counter32
}
mtaGroupInboundErrorCount OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Count of the number of errors of a given type that have
been accumulated in assocation with a particular group
while processing incoming messages. In the case of SMTP
these will typically be errors reporting by an SMTP
server to the remote client; in the case of X.400
these will typically be errors encountered while
processing an incoming message."
::= {mtaGroupErrorEntry 1}
mtaGroupInternalErrorCount OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Count of the number of errors of a given type that have
been accumulated in assocation with a particular group
during internal MTA processing."
::= {mtaGroupErrorEntry 2}
mtaGroupOutboundErrorCount OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Count of the number of errors of a given type that have
been accumulated in assocation with a particular group's
outbound connection activities. In the case of an SMTP
client these will typically be errors reported while
attempting to contact or while communicating with the
remote SMTP server. In the case of X.400 these will
typically be errors encountered while constructing
or attempting to deliver an outgoing message."
::= {mtaGroupErrorEntry 3}
-- Conformance information
mtaConformance OBJECT IDENTIFIER ::= {mta 4}
mtaGroups OBJECT IDENTIFIER ::= {mtaConformance 1}
mtaCompliances OBJECT IDENTIFIER ::= {mtaConformance 2}
-- Compliance statements
mtaCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities which
implement the Mail Monitoring MIB for basic
monitoring of MTAs."
MODULE -- this module
MANDATORY-GROUPS {mtaGroup}
::= {mtaCompliances 1}
mtaAssocCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities which
implement the Mail Monitoring MIB for monitoring of
MTAs and their associations."
MODULE -- this module
MANDATORY-GROUPS {mtaGroup, mtaAssocGroup}
::= {mtaCompliances 2}
mtaErrorCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities which
implement the Mail Monitoring MIB for monitoring of
MTAs and detailed errors."
MODULE -- this module
MANDATORY-GROUPS {mtaGroup, mtaErrorGroup}
::= {mtaCompliances 3}
mtaFullCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities which
implement the full Mail Monitoring MIB for monitoring
of MTAs, associations, and detailed errors."
MODULE -- this module
MANDATORY-GROUPS {mtaGroup, mtaAssocGroup, mtaErrorGroup}
::= {mtaCompliances 4}
-- Units of conformance
mtaGroup OBJECT-GROUP
OBJECTS {
mtaReceivedMessages, mtaStoredMessages,
mtaTransmittedMessages, mtaReceivedVolume, mtaStoredVolume,
mtaTransmittedVolume, mtaReceivedRecipients,
mtaStoredRecipients, mtaTransmittedRecipients,
mtaSuccessfulConvertedMessages, mtaFailedConvertedMessages,
mtaGroupReceivedMessages, mtaGroupRejectedMessages,
mtaGroupStoredMessages, mtaGroupTransmittedMessages,
mtaGroupReceivedVolume, mtaGroupStoredVolume,
mtaGroupTransmittedVolume, mtaGroupReceivedRecipients,
mtaGroupStoredRecipients, mtaGroupTransmittedRecipients,
mtaGroupOldestMessageStored, mtaGroupInboundAssociations,
mtaGroupOutboundAssociations, mtaLoopsDetected,
mtaGroupAccumulatedInboundAssociations,
mtaGroupAccumulatedOutboundAssociations,
mtaGroupLastInboundActivity, mtaGroupLastOutboundActivity,
mtaGroupLastOutboundAssociationAttempt,
mtaGroupRejectedInboundAssociations,
mtaGroupFailedOutboundAssociations,
mtaGroupInboundRejectionReason,
mtaGroupOutboundConnectFailureReason,
mtaGroupScheduledRetry, mtaGroupMailProtocol, mtaGroupName,
mtaGroupSuccessfulConvertedMessages,
mtaGroupFailedConvertedMessages, mtaGroupDescription,
mtaGroupURL, mtaGroupCreationTime, mtaGroupHierarchy,
mtaGroupOldestMessageId, mtaGroupLoopsDetected}
STATUS current
DESCRIPTION
"A collection of objects providing basic monitoring of MTAs."
::= {mtaGroups 1}
mtaAssocGroup OBJECT-GROUP
OBJECTS {
mtaGroupAssociationIndex}
STATUS current
DESCRIPTION
"A collection of objects providing monitoring of MTA
associations."
::= {mtaGroups 2}
mtaErrorGroup OBJECT-GROUP
OBJECTS {
mtaGroupInboundErrorCount, mtaGroupInternalErrorCount,
mtaGroupOutboundErrorCount}
STATUS current
DESCRIPTION
"A collection of objects providing monitoring of
detailed MTA errors."
::= {mtaGroups 3}
END7. Changes made since RFC 1566 🎀
Here's the glow-up list 💖 Since RFC 1566 [11], these are the ONLY changes made to this document, so nothing sneaky, I promise:
- (1) A bunch of DESCRIPTION fields got reworded, hopefully so they're clearer.
- (2) mtaGroupDescription and mtaGroupURL fields were added. They're there to identify and describe the MTA and its various MTA groups.
- (3) The time since the last outbound association attempt is now separate from the time since the last successful outbound association attempt.
- (4) Conversion operation counters were added.
- (5) A mechanism to explicitly describe group hierarchies was added.
- (6) A mechanism to count specific sorts of errors was added.
- (7) A field for the ID of the oldest message in a group's queue was added.
- (8) Per-MTA and per-group message loop counters were added.
- (9) A new table was added to keep track of any errors an MTA encounters.
8. Acknowledgements 🫶
This document is a work product of the Mail and Directory Management (MADMAN) Working Group of the IETF. It's based on an earlier MIB designed by S. Kille, T. Lenggenhager, D. Partain, and W. Yeong. The Electronic Mail Association's TSC committee was instrumental in giving feedback on and suggesting enhancements to RFC 1566 [11], and that's what led to this document 😭💜
9. References 📚
- [1] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Structure of Management Information for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1902, January 1996.
- [2] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Textual Conventions for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1903, January 1996.
- [3] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Conformance Statements for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1904, January 1996.
- [4] SNMPv2 Working Grou, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996.
- [5] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996.
- [6] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Management Information Base for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1907, January 1996.
- [7] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Coexistence between Version 1 and Version 2 of the Internet-standard Network Management Framework", RFC 1908, January 1996.
- [8] Freed, N., and S. Kille, "The Network Services Monitoring MIB", RFC 2248, January 1998.
- [9] Kille, S., "A String Representation of Distinguished Names", RFC 1779, March 1995.
- [10] Berners-Lee, T., Masinter, L. and M. McCahill, Uniform Resource Locators (URL)", RFC 1738, December 1994.
- [11] Freed, N. and S. Kille, "Mail Monitoring MIB", RFC 1566, January 1994.
- [12] Kille, S., "Mapping between X.400(1988) / ISO 10021 and RFC 822", RFC 1327, May 1992.
- [13] Crocker, D., "Standard for the Format of ARPA Internet Text Message", RFC 822, August 1982.
- [14] Vaudreuil, G., "Enhanced Mail System Status Codes", RFC 1893, January 1996.
10. Security Considerations 🔐💀
Okay, this part is serious, so read it carefully 🙈 This MIB does not offer write access, which means it can't be used to actively attack a system. BUT it does give out passive information about the existence, type, and configuration of applications on a given host, and that could potentially point to some sort of vulnerability. Finally, the information this MIB gives about network usage could be used to analyze network traffic patterns. Not me being dramatic, this is literally the warning 😭
11. Author and Chair Addresses 💌
Ned Freed Innosoft International, Inc. 1050 Lakes Drive West Covina, CA 91790 USA
Phone: +1 626 919 3600 Fax: +1 626 919 3614 EMail: ned.freed@innosoft.com
Steve Kille, MADMAN WG Chair ISODE Consortium The Dome, The Square Richmond TW9 1DT UK
Phone: +44 181 332 9091 EMail: S.Kille@isode.com
12. Full Copyright Statement 🎀
Copyright (C) The Internet Society (1998). All Rights Reserved. 💖
okay so the copyright stuff is actually pretty chill 🦋 you can copy this doc and hand it to anyone, and you can make derivative works that comment on it, explain it, or help people implement it, and publish and distribute those too, whole or in part, no restriction of any kind. the one catch is that the copyright notice and this paragraph have to be included on every single copy and derivative work 📜 ngl that's a very reasonable ask 🫶
BUT the doc itself can't be modified in any way 🙅♀️ so no removing the copyright notice or the references to the Internet Society or other Internet organizations. the exceptions are: developing Internet standards, where the copyright procedures in the Internet Standards process must be followed, or translating it into languages other than English 🌍 that's giving "tidy rules, good vibes" ✨
the permissions are perpetual, and they won't be revoked by the Internet Society or its successors or assigns 💜 that's a permanent yes, bestie 👑
This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 🙈
RPO 🌸
📦 where this page comes from
- ietf: rfc2249 1998-01
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms