There are two kinds of mailboxes in Apple Mail — ones that sync with an associated email server, and “On My Mac” mailboxes that only exist on your Mac. Basically, copy all messages into an “On My Mac” mailbox before you delete the account. First, make a new local mailbox to store the messages after your account is deleted. A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth.Within the Open Systems Interconnection (OSI) network model, MAC addresses are used in the medium access. CHAPTER 7 Question 1: Where are MAC addresses stored for future reference? MAC cache ARP cache Ethernet cache NIC Question 2: When TCP/IP was developed, the host table concept was expanded into a hierarchical name system for matching computer names and numbers using this service: DNS HTTP URNS NSDB Question 3: Which type of attack broadcasts a network request to multiple computers but. MAC addresses are primarily assigned by device manufacturers, and are therefore often referred to as the burned-in address, or as an Ethernet hardware address, hardware address, and physical address. Each address can be stored in hardware, such as the card's read-only memory, or by a firmware mechanism.
01 Jan 2015
Yesterday, I wanted to delete some of the old email accounts I had set up in Apple Mail, but I didn’t want to lose access to their emails because they have information I might want to reference later. There are many reasons you’d want to do this — for example, you have a school-provided account where you lose access upon graduation.
The Solution
There are two kinds of mailboxes in Apple Mail — ones that sync with an associated email server, and “On My Mac” mailboxes that only exist on your Mac. Basically, copy all messages into an “On My Mac” mailbox before you delete the account.
First, make a new local mailbox to store the messages after your account is deleted. Go to Mailbox > New Mailbox and this sheet will show up:
Now go to the mailbox you want to archive and select all the messages. Right click your selection and go to Copy To > (The name of your newly created mailbox).
(Instead of copying the messages, you could also move the associated files, since mailboxes are stored as folders under
~/Library/Mail/
. But that’ll probably break things subtly — maybe Spotlight indexing or something.)Once you’ve made a local copy of every mailbox, you’re now free to delete the account without losing messages.
Ethernet |
Description:
Protocol suite: | Ethernet |
Type: | CSMA/CD Data Link and Physical Layer. |
The Ethernet is a local area network (LAN) set of protocols which serves the physical and data link layers. Ethernet utilizes a linear bus or star topology. Ethernet served as the basis for the IEEE 802.3 standard.
The Ethernet deals with the low level - Physical and Data Link Layers.
The Data Link Layer is divided into two sublayers:
- Logical Link Control (LLC). This sublayer establishes the transmission paths between computers or devices on a network.
- Media Access Control (MAC). On a network, the network interface card (NIC) has an unique hardware address which identifies a computer or peripheral device. The hardware address is used for the MAC sublayer addressing. Ethernet uses the MAC hardware addresses for the source and destination for each packet transmitted.
Ethernet uses CSMA/CD when transmitting packets. The Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is an algorithm, for transmitting and receiving packets over a common network hardware medium, by aiding in avoiding transmission collisions. The network is checked for other transmissions; when the way is clear, the computer transmissions can begin. If a collision is detected the packet is retransmitted later.
Address resolution protocol (ARP) is a TCP/IP protocol used to map IP network addresses to a hardware interface physical addresses.
Reverse address resolution protocol (RARP) is a TCP/IP protocol used to map hardware interface physical addresses to IP network addresses.
Some of the listed RFCs for Ethernet implement the Simple Network Management Protocol (SNMP).
Ethernet frame.
Preamble | Ethernet 802.3 packet | Data | FCS |
Preamble. 8 bytes.
For synchronization, this indicates that the frame is about to begin. Included is the Start Frame Delimiter field that ends with two1s.
For synchronization, this indicates that the frame is about to begin. Included is the Start Frame Delimiter field that ends with two1s.
Ethernet 802.3 Packet format.
00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Destination Address | |||||||||||||||
Source Address | |||||||||||||||
EtherType | |||||||||||||||
Data ::: |
Destination Address. 6 bytes.
The address(es) are specified for a unicast, multicast (subgroup), or broadcast (an entire group).
The address(es) are specified for a unicast, multicast (subgroup), or broadcast (an entire group).
Source Address. 6 bytes.
The address is for a unicast (single computer or device).
The address is for a unicast (single computer or device).
EtherType. 16 bits.
Which upper layer protocol will utilized the Ethernet frame.
Which upper layer protocol will utilized the Ethernet frame.
Data. variable, 46-1500 bytes.
FCS, Frame Check Sequence. 4 bytes.
Error checking with a Cycle Redundancy Check (CRC) value.
Error checking with a Cycle Redundancy Check (CRC) value.
Ethernet 802.2 LLC Packet format:
00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
---|---|---|---|---|---|---|---|
DSAP | |||||||
SSAP | |||||||
Control |
LLC, Link Layer Control.
The Logical Link Control (LLC) consists of the DSAP, SSAP, and Control fields. The function is to establish paths to the SAP addresses for the Network Layer protocol services. This part gets inserted into the data field.
The Logical Link Control (LLC) consists of the DSAP, SSAP, and Control fields. The function is to establish paths to the SAP addresses for the Network Layer protocol services. This part gets inserted into the data field.
DSAP, Destination Service Access Point. 8 bits.
The destination network layer, protocol type of the packet.
The destination network layer, protocol type of the packet.
SSAP, Source Service Access Point. 8 bits.
The source network layer, protocol type of the packet.
The source network layer, protocol type of the packet.
Control. 8 bits.
Ethernet SNAP Packet format:
00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
---|---|---|---|---|---|---|---|
Organization Code | |||||||
EtherType |
Ethernet SNAP. Organization Code and Ethertype fields follow the LLC fields.
Organization Code. 3 bytes.
Which organization assigned the Ethernet Type field.
Which organization assigned the Ethernet Type field.
EtherType. 2 bytes.
Defines which upper layer protocol will utilize the Ethernet frame.
Defines which upper layer protocol will utilize the Ethernet frame.
Value | EtherTypes |
---|---|
0x0800 | IP. |
0x0806 | ARP, Address Resolution Protocol. |
0x8035 | RARP, Reverse Address Resolution Protocol. |
0x809B | AppleTalk. |
0x80F3 | AppleTalk ARP. |
0x8137 | NetWare IPX/SPX. |
Glossary:
![Addresses Addresses](/uploads/1/1/9/8/119847090/513494592.png)
Address Mapping.
(RFC 894, page 2) Mappings between 32-bit Internet addresses and 48-bit Ethernet addresses could be accomplished through the Address Resolution Protocol (ARP) [RFC 826]. Internet addresses are assigned arbitrarily on some Internet network. Each host's implementation must know its own Internet address and respond to Ethernet Address Resolution packets appropriately. It should also use ARP to translate Internet addresses to Ethernet addresses when needed.
(RFC 894, page 2) Mappings between 32-bit Internet addresses and 48-bit Ethernet addresses could be accomplished through the Address Resolution Protocol (ARP) [RFC 826]. Internet addresses are assigned arbitrarily on some Internet network. Each host's implementation must know its own Internet address and respond to Ethernet Address Resolution packets appropriately. It should also use ARP to translate Internet addresses to Ethernet addresses when needed.
Managed Objects.
(RFC 2358, page 3) Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) [Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization, International Standard 8824, December 1987.] defined in the SMI [RFC 1902]. In particular, each object object type is named by an OBJECT IDENTIFIER, an administratively assigned name. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the descriptor, to refer to the object type.
(RFC 2358, page 3) Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) [Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization, International Standard 8824, December 1987.] defined in the SMI [RFC 1902]. In particular, each object object type is named by an OBJECT IDENTIFIER, an administratively assigned name. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the descriptor, to refer to the object type.
SNMP, Network Management Framework.
(RFC 2358 , pages 2 and 3) The SNMP Network Management Framework consists of several components. For the purpose of this specification, the applicable components of the Framework are the SMI and related documents [RFC 1902, RFC 1903, RFC 1904], which define the mechanisms used for describing and naming objects for the purpose of management. The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
(RFC 2358 , pages 2 and 3) The SNMP Network Management Framework consists of several components. For the purpose of this specification, the applicable components of the Framework are the SMI and related documents [RFC 1902, RFC 1903, RFC 1904], which define the mechanisms used for describing and naming objects for the purpose of management. The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
RFCs:
![Future Future](/uploads/1/1/9/8/119847090/198712355.png)
[RFC 826]An Ethernet Address Resolution Protocol.
[RFC 894] A Standard for the Transmission of IP Datagrams over Ethernet Networks.
[RFC 895] A Standard for the Transmission of IP Datagrams over Experimental Ethernet Networks.
[RFC 1029] A MORE FAULT TOLERANT APPROACH TO ADDRESS RESOLUTION FOR A MULTI-LAN SYSTEM OF ETHERNETS.
[RFC 1089] SNMP over Ethernet.
[RFC 1369] Implementation Notes and Experience for The Internet Ethernet MIB.
[RFC 1643] Definitions of Managed Objects for the Ethernet-like Interface Types.
Where Are Mac Addresses Stored For Future Reference Online
- Obsoletes: RFC 1284, RFC 1398, RFC 1623.
[RFC 1972] A Method for the Transmission of IPv6 Packets over Ethernet Networks.
[RFC 2358] Definitions of Managed Objects for the Ethernet-like Interface Types.
- Obsoletes: RFC 1650.
Obsolete RFCs:
[RFC 1284] Definitions of Managed Objects for the Ethernet-like Interface Types.
[RFC 1398] Definitions of Managed Objects for the Ethernet-like Interface Types.
[RFC 1623] Definitions of Managed Objects for the Ethernet-like Interface Types.
[RFC 1650] Definitions of Managed Objects for the Ethernet-like Interface Types using SMIv2.
Where Are Mac Addresses Stored For Future Reference Pdf
References:
Chappell, Laura and Dan Hakes. Novell's Guide to NetWare LAN Analysis (First Edition). Sybex Inc. and Novell Press, 1993.
Chappell, Laura and Dan Hakes. Novell's Guide to NetWare LAN Analysis (Second Edition). Sybex Inc. and Novell Press, 1994.
Where Are Mac Addresses Stored For Future Reference Chart
Naugle, Matthew. Network Protocol Handbook. McGraw-Hill, Inc., 1994.
Where Are Mac Addresses Stored For Future Reference In Excel
Networking Technologies. Novell Inc.