31.1. DNS Resource

31.1. DNS Resource
	Chapter 31. DNS - Domain Name System

The Abilis CPX DNS resource may behave as a DNS Resolver, as a DNS Relay or as a DNS Server too.

31.1.1. Activating the DNS resource

Add the resource to the Abilis system with the following command.

[12:18:28] ABILIS_CPX:a res:dns

RES:DNS ALREADY EXISTS

The DNS resource may already exist in the system, but may not yet be active: set it active with the command:

[12:18:31] ABILIS_CPX:s act res:dns

COMMAND EXECUTED

	Caution
	After adding or setting the DNS active, you must restart the Abilis to make the resource running (use the command warm start to reboot the Abilis).

[17:14:59] ABILIS_CPX:s p dns act:yes

COMMAND EXECUTED

[17:15:17] ABILIS_CPX:d p dns

RES:Dns -----------------------------------------------------------------------
Run    DESCR:Domain_Name_System
       LOG:NO           ACT:YES 
       udp-locport:53   SRCADD:OUT-IP                      TOS:0-N      
       wdir:C:\APP\DNS\
       - Resolver -------------------------------------------------------------
       SERVERS:AUTO
       PRIMARY:#                 SECONDARY:#
       DELAY:5                   RTY:1                    
       CACHE:YES                 cache-size:500
       - Relay/Server ---------------------------------------------------------
       RELAY:NO                  relay-size:500            RELAY-TOUT:10  
       RELAY-BLACKLIST:YES       RELAY-BLACKLIST-BYPASS:#
       RELAY-LOG-REQUESTERS:
       SERVER:YES
       IPSRC:*                   IPSRCLIST:#

31.1.2. DNS resource parameters

Use the following command to display the parameters of the resource; the command d p dns ? displays the meaning of all parameters.

[12:18:35] ABILIS_CPX:d p dns

RES:Dns -----------------------------------------------------------------------
Run    DESCR:Domain_Name_System
       LOG:NO           ACT:YES 
       udp-locport:53   SRCADD:OUT-IP                      TOS:0-N      
       wdir:C:\APP\DNS\
       - Resolver -------------------------------------------------------------
       SERVERS:AUTO
       PRIMARY:#                 SECONDARY:#
       DELAY:5                   RTY:1                    
       CACHE:YES                 cache-size:500
       - Relay/Server ---------------------------------------------------------
       RELAY:NO                  relay-size:500            RELAY-TOUT:10  
       RELAY-BLACKLIST:YES       RELAY-BLACKLIST-BYPASS:#
       RELAY-LOG-REQUESTERS:
       SERVER:YES
       IPSRC:*                   IPSRCLIST:#

Meaning of the most important parameters:

LOG

Logging functionalities activation/deactivation.

ACT

Operation activation [NO, YES].

udp-locport

DNS-relay listening UDP port [53].

SRCADD

Source IP address for outgoing requests [R-ID, OUT-IP, 1-126.x.x.x, 127.0.0.1, 128-223.x.x.x].

TOS

Sets the TOS value for DNS service; TOS or DS field:

p-t: PRECEDENCE-TOS, 'p' [0..7], 't' [N, D, T, R, C];
bbbbbb: DS value bit by bit, 'b' [0, 1].

wdir

Working directory. Full path with drive letter ['C'..'Z'] terminated by '\'. Max 128 chars. Spaces require double quotes (E.g. "C:\My dir\").

SERVERS

Servers IP resource [AUTO, Ip-nnn, STATIC], where 'nnn' is an IP resource index [1..250].

AUTO: DNS resolver uses the servers retrieved by an IP resources that negotiates them e.g. IP-PPP. DNS: parameter of IP resources must be set to RETRIEVE;
Ip-nnn: DSN resolver uses the available servers through Ip-nnn resource;
STATIC: DNS resolver uses PRIMARY and SECONDARY servers.

PRIMARY

DNS primary server IP address [#, 1-126.x.x.x, 127.0.0.1, 128-223.x.x.x].

SECONDARY

DNS secondary server IP address [#, 1-126.x.x.x, 127.0.0.1, 128-223.x.x.x].

DELAY

Time that resolver waits for server's responses [1..15 sec.].

RTY

Number of attempts to perform DNS request [1..10]. Sets how many times a request has to be sent to the DNS server if the DNS Resolver doesn't get any response in the expected time interval fixed in the DELAY parameter.

CACHE

Activation/deactivation of DNS cache [NO, YES].

cache-size

Size of DNS cache [500..20000].

RELAY

Enable/disable the DNS Relay feature [NO, YES]. DNS relay allows the relay of external DNS requests of DNS clients from CPX to DNS server.

relay-size

Size of DNS relay table [500..20000].

RELAY-TOUT

Timeout waiting server response for relayed requests [5..60 sec.].

RELAY-BLACKLIST

Enable/disable DNS Relay blacklist service [NO, YES].

RELAY-BLACKLIST-BYPASS

List of IP addresses that bypass Relay blacklist service [ListName, #].

RELAY-LOG-REQUESTERS

List of requester(s) IP addresses that are used to filter DNS log. Empty or max 3 IP addresses separated by separated by ',' (comma).

SERVER

Enable/disable local DNS Server [NO, YES].

IPSRC

Accepted client's IP address [*, 1-126.x.x.x, 127.0.0.1, 128-223.x.x.x].

IPSRCLIST

List of further accepted source IP addresses [#, IP/IR/RU/MR listname].

The following command allows the administrator to change the configuration of the resource:

s p dns parameter:value...

	Caution
	To activate the changes made on the upper case parameters, execute the initialization command init res:dns; while to set act the changes made on the lowercase parameters a save conf and an Abilis restart are required (i.e. With warm start command).