Monday, May 6, 2013
Sunday, September 11, 2011
VoiP: Distrubuted vs Centralized Call Control
Distributed Infrastructure: This infrastructure is consists of having a CMX system in place for local VoiP services. Administration is not centralized, instead distributed among satellite locations in a scenario with VoiP subscribers that total over 100 users.*
- Protocols include: H.323 & SIP
Centralized: Combines the use of Call Agent to handling signaling and call processing. The voice gateway translates audio signals into voice packets after the call has been setup. Also, having Call Agent allows for centralized administration and can handle users that total in excess of 100 subscribers.*
- Protocol includes*: MGCP
- Protocols include: H.323 & SIP
Centralized: Combines the use of Call Agent to handling signaling and call processing. The voice gateway translates audio signals into voice packets after the call has been setup. Also, having Call Agent allows for centralized administration and can handle users that total in excess of 100 subscribers.*
- Protocol includes*: MGCP
Saturday, September 10, 2011
Name Resolution
There are six types of name to IP address translation technologies in use by Windows-based computers today:
LMHOSTS: A static file within a computer (located in: %SystemRoot%\System32\Drivers\Etc *or for 64-bit OSs systems: %SystemRoot%\SysWOW64\Drivers\Etc*) with IP addresses corresponding to NetBIOS names. This is mainly used for LAN Manager NET utilities (i.e: "net view") and entries can be outside of the local subnet.
- LMHOSTS file must be manually created (Lmhosts.sam is a preexisting sample file). When you create the file, leave it with no extension.
Reference: http://support.microsoft.com/kb/180094 for proper Lmhost file configuration.
HOSTS: A static file within a computer (located in: %SystemRoot%\System32\Drivers\Etc or for 64-bit OSs systems: %SystemRoot%\SysWOW64\Drivers\Etc) used for TCP/IP utilities such as ping, telnet, FTP, etc.
- The hosts file should be named "hosts" without an extension.
- Entries are case sensitive and multiple entries are permissible to reach the host (i.e: host1.domain.com, HOST1.DOMAIN.COM)
Reference http://support.microsoft.com/kb/972034 to bring the hosts file to default.
- Microsoft TechNet states that entries of the Lmhosts file are not case sensitive in one entry but says that domain entries are in another. The domain name will be referenced by NetBT, and NetBT needs capitalized letters to reference the host. Other entries however may not need to be that way.
* More research is to be done regarding the HOSTS file
NetBIOS: Only IPv4 support, supported on all Windows OSs by utilizing broadcasts.
There are four classifications defined, distinguished as "modes," that describe how NetBIOS is executed on nodes which consists of variations of network broadcasts and WINS server querying.
1) Broadcast (B-node): Broadcast for NetBIOS name registration
2) Point-to-Point (P-node): Query WINS server for NetBIOS name resolution.
3) Mixed Mode (M-node): Broadcast before WINS server query
4) Hybrid (H-node) (Windows default mode): Query WINS server, use the LMHOSTS file, then use broadcasts
The modes that take a multi-layered approach, that is, modes that use combinations of broadcasts, WINS server querying, &/or the LMHOSTS file, use if/then logic to move to the next sequential step. For example, a m-node will not move on to a WINS server query if the broadcast is successful.*
WINS: Utilizes NetBIOS to reference name-to-IP address (NTIP) translation through its own NTIP repository. WINS can translate nodees outside of the local subnet.
Local Link Multicast Name Resolution (LLMNR): IPv4 and IPv6 support. All OSs Vista and after support LLMNR and operate on multicast.
- To find a host, LLMNR sends a multicast on IPv6 and IPv4 protocols. The computer with the relevant name-to-IP address will respond with their answer.
Domain Name System (DNS): Naming structure is hierarchical beginning with the root, defined as "" (null), with a TLD or top level domain name such as "com," "co.uk" "mil," and so forth. I assume that this is for versatility purposes as domain names can be converted to different symbols while utilizing alphanumerics to define domain names. For example, FQDNs can be transitioned to www-domain-domain. instead of www.domain.com.. Moving left within the structure from the period and TLD (".com"), you get into specific domains, child domains, etc with a limit of 127 entries per a given tree. Names must be registered within the DNS server in order for names to be resolved.
The internet DNS infrastructure is centralized within specific repositories called root hint servers for host name resolution. Within intranets, local DNS servers with name to IP address & vice versa repositories are standard. Be aware that without root hint servers, it would be difficult to resolve a name to an IP address for hosts for domains w/TLDs as there are many computers and networks that need to be queried in order to find a specific host.
The DNS structure can be likened to a tree. The root, or base of the naming structure is blank, and once the TLD and domain has been defined (the trunk), you can add hosts (leaves), subdomains/child domains (branches) and their corresponding hosts (leaves) can be defined within it.
LMHOSTS: A static file within a computer (located in: %SystemRoot%\System32\Drivers\Etc *or for 64-bit OSs systems: %SystemRoot%\SysWOW64\Drivers\Etc*) with IP addresses corresponding to NetBIOS names. This is mainly used for LAN Manager NET utilities (i.e: "net view") and entries can be outside of the local subnet.
- LMHOSTS file must be manually created (Lmhosts.sam is a preexisting sample file). When you create the file, leave it with no extension.
Reference: http://support.microsoft.com/kb/180094 for proper Lmhost file configuration.
HOSTS: A static file within a computer (located in: %SystemRoot%\System32\Drivers\Etc or for 64-bit OSs systems: %SystemRoot%\SysWOW64\Drivers\Etc) used for TCP/IP utilities such as ping, telnet, FTP, etc.
- The hosts file should be named "hosts" without an extension.
- Entries are case sensitive and multiple entries are permissible to reach the host (i.e: host1.domain.com, HOST1.DOMAIN.COM)
Reference http://support.microsoft.com/kb/972034 to bring the hosts file to default.
- Microsoft TechNet states that entries of the Lmhosts file are not case sensitive in one entry but says that domain entries are in another. The domain name will be referenced by NetBT, and NetBT needs capitalized letters to reference the host. Other entries however may not need to be that way.
* More research is to be done regarding the HOSTS file
NetBIOS: Only IPv4 support, supported on all Windows OSs by utilizing broadcasts.
There are four classifications defined, distinguished as "modes," that describe how NetBIOS is executed on nodes which consists of variations of network broadcasts and WINS server querying.
1) Broadcast (B-node): Broadcast for NetBIOS name registration
2) Point-to-Point (P-node): Query WINS server for NetBIOS name resolution.
3) Mixed Mode (M-node): Broadcast before WINS server query
4) Hybrid (H-node) (Windows default mode): Query WINS server, use the LMHOSTS file, then use broadcasts
The modes that take a multi-layered approach, that is, modes that use combinations of broadcasts, WINS server querying, &/or the LMHOSTS file, use if/then logic to move to the next sequential step. For example, a m-node will not move on to a WINS server query if the broadcast is successful.*
WINS: Utilizes NetBIOS to reference name-to-IP address (NTIP) translation through its own NTIP repository. WINS can translate nodees outside of the local subnet.
Local Link Multicast Name Resolution (LLMNR): IPv4 and IPv6 support. All OSs Vista and after support LLMNR and operate on multicast.
- To find a host, LLMNR sends a multicast on IPv6 and IPv4 protocols. The computer with the relevant name-to-IP address will respond with their answer.
Domain Name System (DNS): Naming structure is hierarchical beginning with the root, defined as "" (null), with a TLD or top level domain name such as "com," "co.uk" "mil," and so forth. I assume that this is for versatility purposes as domain names can be converted to different symbols while utilizing alphanumerics to define domain names. For example, FQDNs can be transitioned to www-domain-domain. instead of www.domain.com.. Moving left within the structure from the period and TLD (".com"), you get into specific domains, child domains, etc with a limit of 127 entries per a given tree. Names must be registered within the DNS server in order for names to be resolved.
The internet DNS infrastructure is centralized within specific repositories called root hint servers for host name resolution. Within intranets, local DNS servers with name to IP address & vice versa repositories are standard. Be aware that without root hint servers, it would be difficult to resolve a name to an IP address for hosts for domains w/TLDs as there are many computers and networks that need to be queried in order to find a specific host.
The DNS structure can be likened to a tree. The root, or base of the naming structure is blank, and once the TLD and domain has been defined (the trunk), you can add hosts (leaves), subdomains/child domains (branches) and their corresponding hosts (leaves) can be defined within it.
Friday, September 9, 2011
ISATAP, 6to4, & Teredo
Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) (IPv4toIPv6INTRANET): The goal of ISATAP is to allow IPv4 hosts to communicate to IPv6 hosts on an intranet. It essentially handles IPv4-only to IPv6-only intranet communication executions.
In Windows Server 2008 R2, this is referenced as "tunnel adapter isatap."
6to4 (IPv6toIPv4WANtoIPv6): The goal of 6to4 is to allow communications of IPv6 end devices to communicate over an IPv4 WAN infrastructure. 6to4 essentially handles IPv6 to IPv4 (WAN) to IPv6 (6/4/6) communication executions.
Clients using 6to4 will have their routers IPv4 address embedded in their IPv6 address.
If you intend on communicating to native IPv6 networks (basically, a non-6to4 network) while using 6to4 on your end, it will require you to utilize a 6to4 relay as a bridge between the IPv4 network and the IPv6 endpoint:
1) 6to4 router: The router prepares IPv6 packets to be sent over the IPv4 WAN infrastructure.
2) 6to4 relay: The relay prepares & forwards the IPv4 packet to traverse the native IPv6 network.
Clients using 6to4 will have their routers IPv4 address embedded in their IPv6 address.
If you intend on communicating to native IPv6 networks (basically, a non-6to4 network) while using 6to4 on your end, it will require you to utilize a 6to4 relay as a bridge between the IPv4 network and the IPv6 endpoint:
1) 6to4 router: The router prepares IPv6 packets to be sent over the IPv4 WAN infrastructure.
2) 6to4 relay: The relay prepares & forwards the IPv4 packet to traverse the native IPv6 network.
Teredo (IPv4NATtoIPv6): The goal of Teredo is for IPv4 NAT configured hosts to reach IPv6 only hosts or other NAT configured hosts over the internet.
Teredo needs three infrastructure components to operate correctly:
1) Teredo Client: The computer that is configured w/NAT w/an IPv4 address.
2) Teredo Server: A public server connected to the IPv4 and IPv6 internet (Microsoft deployed).
3) Teredo Relay: IPv6/IPv4 router that can forward packets to Teredo enabled clients & IPv6-only hosts.
A) Teredo host-specific relay: This is a host w/IPv4 and IPv6 enabled that can act as a Teredo relay.
The Teredo client creates a Teredo tunneling interface and w/the help of the Teredo server, creates a routable IPv6 address. The Teredo server facilitates the initial communications between a Teredo client and an IPv6 host or another Teredo enabled client.
Teredo host-specific relay is automatically enabled by default if a global address is already configured. If it does not, then it is configured as a Teredo client.
IPv6
Quick Facts:
1) Utilizes hexadecimal (base 16) notation consistent of four characters within an eight block parameter. 16-bits per subsection thus equals 128 bits total.
A) Remember: In hexadecimal F+1 = 16. After translating decimal 16 into hex it will = 10.
2) Colons are used to separate sections within IPv6 unlike IPv4 which uses period marks.
3) An easier way of writing/reading IPv6 is by becoming aware that leading (beginning) zeros can be neglected from the entire IPv6 address.
4) You can simply the IPv6 notation in three ways.
1) If you have any leading zeros, you can leave them out.
2) If you have an entire subsection &/or consecutive subsections with a value of zero, you can represent that with two consecutive colons.
(i.e: 2001:DB8:3FA9:0000:0000:0000:D3:9C5A becomes 2001:DB8:3FA9::D3:9C5A; ::01 is loopback)
5) IPv6 is separated into two sections: the first half = network ID, the second = MAC address or randomly assigned number.*
6) With the Zone ID, you are able to determine which interface belongs to which local segment when using certain IPv6 address classifications. Zone IDs are distinguishable by a "%" symbol and a numerical value after a qualifying IPv6 address.
7) Clients receive an automatically configured IPv6 address from a router*. Once an address is given to an interface, it is checked by the computer through a Neighbor Solicitation message to other hosts to see if it is unique. If the address is already being used then it is considered invalid, else, it will consider the tentative address valid. There are then two types of valid address types: preferred and deprecated. Preferred means that the IPv6 address is within the address usage time-frame while deprecated means the opposite. You can still execute communications with a deprecated address.
7) There are three types of IPv6 addresses
A) Global: A unique network identifier provided by IANA. Similar to an external address in IPv4.
1) First 48 bits = Network ID
2) 16 bits = Subnet ID
3) 64 bits = Interface ID
B) Link-Local: Unroutable and automatically assigned address used for local communication. Similar to APIPA addresses.
1) Always starts with "fe80"
2) Structure consistent of half of the address being the unroutable local address while the rest is for the interface ID.
C) Unique Local: Nonroutable, and configurable IP addresses for use on local segments. Equivalent to private IP addresses such as 192.168.1 or 10.0.0 etc.
1) Always starts with FD00. It is possible that FC00::/8 will be used in the future.
2) Structure consists of the first 8 bits that are indicative of a unique local address. The next 40 bits are the Global ID, which IDs the segment. The next 16 represent the subnet and the last 64 represent the interface ID.
1) Utilizes hexadecimal (base 16) notation consistent of four characters within an eight block parameter. 16-bits per subsection thus equals 128 bits total.
A) Remember: In hexadecimal F+1 = 16. After translating decimal 16 into hex it will = 10.
2) Colons are used to separate sections within IPv6 unlike IPv4 which uses period marks.
3) An easier way of writing/reading IPv6 is by becoming aware that leading (beginning) zeros can be neglected from the entire IPv6 address.
4) You can simply the IPv6 notation in three ways.
1) If you have any leading zeros, you can leave them out.
2) If you have an entire subsection &/or consecutive subsections with a value of zero, you can represent that with two consecutive colons.
(i.e: 2001:DB8:3FA9:0000:0000:0000:D3:9C5A becomes 2001:DB8:3FA9::D3:9C5A; ::01 is loopback)
5) IPv6 is separated into two sections: the first half = network ID, the second = MAC address or randomly assigned number.*
6) With the Zone ID, you are able to determine which interface belongs to which local segment when using certain IPv6 address classifications. Zone IDs are distinguishable by a "%" symbol and a numerical value after a qualifying IPv6 address.
7) Clients receive an automatically configured IPv6 address from a router*. Once an address is given to an interface, it is checked by the computer through a Neighbor Solicitation message to other hosts to see if it is unique. If the address is already being used then it is considered invalid, else, it will consider the tentative address valid. There are then two types of valid address types: preferred and deprecated. Preferred means that the IPv6 address is within the address usage time-frame while deprecated means the opposite. You can still execute communications with a deprecated address.
7) There are three types of IPv6 addresses
A) Global: A unique network identifier provided by IANA. Similar to an external address in IPv4.
1) First 48 bits = Network ID
2) 16 bits = Subnet ID
3) 64 bits = Interface ID
B) Link-Local: Unroutable and automatically assigned address used for local communication. Similar to APIPA addresses.
1) Always starts with "fe80"
2) Structure consistent of half of the address being the unroutable local address while the rest is for the interface ID.
C) Unique Local: Nonroutable, and configurable IP addresses for use on local segments. Equivalent to private IP addresses such as 192.168.1 or 10.0.0 etc.
1) Always starts with FD00. It is possible that FC00::/8 will be used in the future.
2) Structure consists of the first 8 bits that are indicative of a unique local address. The next 40 bits are the Global ID, which IDs the segment. The next 16 represent the subnet and the last 64 represent the interface ID.
Friday, September 2, 2011
Windows Server : Differences Between Domain Local, Global, and Universal Groups
Domain Local: Certain security principals can be associated to this group from the same domain, same forest, or members from a trusted external domain. These SPs are allowed access to local resources only.
Global: Certain security principals can be associated to this group from the same domain only. These SPs are allowed access to resources within any trusted domain.
Universal: Certain security principals from a domain within the forest are allowed access to resources in the forest. Members from an trusted external domain cannot be added to this group.
Global: Certain security principals can be associated to this group from the same domain only. These SPs are allowed access to resources within any trusted domain.
Universal: Certain security principals from a domain within the forest are allowed access to resources in the forest. Members from an trusted external domain cannot be added to this group.
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