Host

El comando host es una utilidad simple para realizar búsquedas de DNS. Normalmente se utiliza para convertir nombres a direcciones IP y viceversa.

Le debemos pasar el nombre que dominio que queremos buscar. También puede ser una dirección IPv4 decimal con puntos o bien una dirección IPv6 delimitada por puntos, en cuyo caso el host realizará por defecto una búsqueda inversa para esa dirección.

Sin parámetros

Podemos utilizar el sitio de la página web

┌──(nato㉿kali)-[~]
└─$ host nmap.org
nmap.org has address 50.116.1.184
nmap.org mail is handled by 5 alt1.aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx3.googlemail.com.
nmap.org mail is handled by 1 aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx2.googlemail.com.
nmap.org mail is handled by 5 alt2.aspmx.l.google.com.

O podemos utilizar la misma IP del sitio web

┌──(nato㉿kali)-[~]
└─$ host 50.116.1.184
184.1.116.50.in-addr.arpa domain name pointer ack.nmap.org.

En modo detalle

Para que muestre más información se debe habilitar el modo verbose, que se encuentra en la mayoría de los comandos en GNU/Linux. Para ello se utiliza los parámetros -v o -a.

┌──(nato㉿kali)-[~]
└─$ host -v nmap.org 
Trying "nmap.org"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61082
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;nmap.org.			IN	A

;; ANSWER SECTION:
nmap.org.		5	IN	A	50.116.1.184

Received 42 bytes from 192.168.23.2#53 in 8 ms
Trying "nmap.org"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19687
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;nmap.org.			IN	AAAA

Received 26 bytes from 192.168.23.2#53 in 28 ms
Trying "nmap.org"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39893
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;nmap.org.			IN	MX

;; ANSWER SECTION:
nmap.org.		5	IN	MX	10 aspmx3.googlemail.com.
nmap.org.		5	IN	MX	1 aspmx.l.google.com.
nmap.org.		5	IN	MX	10 aspmx2.googlemail.com.
nmap.org.		5	IN	MX	5 alt2.aspmx.l.google.com.
nmap.org.		5	IN	MX	5 alt1.aspmx.l.google.com.

Received 159 bytes from 192.168.23.2#53 in 32 ms

Especificar el tipo de consulta

Para especificar el tipo de consulta que queremos hacer debemos utilizar el parámetro -t.

Registro ns

┌──(nato㉿kali)-[~]
└─$ host -t ns nmap.org
nmap.org name server ns1.linode.com.
nmap.org name server ns2.linode.com.
nmap.org name server ns3.linode.com.
nmap.org name server ns4.linode.com.
nmap.org name server ns5.linode.com.

Registro SOA

┌──(nato㉿kali)-[~]
└─$ host -t soa nmap.org
nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600

Registro TXT

┌──(nato㉿kali)-[~]
└─$ host -t txt nmap.org
nmap.org descriptive text "google-site-verification=SrtYpJGxZzMTcczZG44XtLVK-sEPit9bputDjWc0lF4"
nmap.org descriptive text "v=spf1 a mx ptr ip4:50.116.1.184 ip6:2600:3c01::f03c:91ff:fe98:ff4e ip6:2600:3c01:e000:3e6::6d4e:7061 include:_spf.google.com ~all"

Registro a

┌──(nato㉿kali)-[~]
└─$ host -t a nmap.org
nmap.org has address 50.116.1.184

Registro aaaa

┌──(nato㉿kali)-[~]
└─$ host -t aaaa nmap.org
nmap.org has no AAAA record

Registro mx

┌──(nato㉿kali)-[~]
└─$ host -t mx nmap.org
nmap.org mail is handled by 5 alt1.aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx2.googlemail.com.
nmap.org mail is handled by 1 aspmx.l.google.com.
nmap.org mail is handled by 5 alt2.aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx3.googlemail.com.

Registro CNAME

┌──(nato㉿kali)-[~]
└─$ host -t CNAME nmap.org
nmap.org has no CNAME record

Forzar consultas

IPv4

┌──(nato㉿kali)-[~]
└─$ host -4 nmap.org  
nmap.org has address 50.116.1.184
nmap.org mail is handled by 10 aspmx2.googlemail.com.
nmap.org mail is handled by 5 alt2.aspmx.l.google.com.
nmap.org mail is handled by 5 alt1.aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx3.googlemail.com.
nmap.org mail is handled by 1 aspmx.l.google.com.

IPv6

┌──(nato㉿kali)-[~]
└─$ host -6 nmap.org
;; communications error to ::1#53: connection refused
;; communications error to ::1#53: connection refused
;; no servers could be reached

Consultar Registros SOA

Para realizar este tipo de consultas de los registros SOA en servidores de nombre autorizados, se utiliza el parámetro -C.

┌──(nato㉿kali)-[~]
└─$ host -C nmap.org    
Nameserver 92.123.94.3:
	nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600
Nameserver 92.123.95.2:
	nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600
Nameserver 92.123.94.2:
	nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600
Nameserver 92.123.95.4:
	nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600
Nameserver 92.123.95.3:
	nmap.org has SOA record ns1.linode.com. hostmaster.insecure.org. 2021000013 14400 14400 1209600 3600

Comprobar número de reintentos

Para definir esto se utiliza el parámetro -R seguido del número de reintentos que se le desea otorgar.

┌──(nato㉿kali)-[~]
└─$ host -R 3 nmap.org 
nmap.org has address 50.116.1.184
nmap.org mail is handled by 1 aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx2.googlemail.com.
nmap.org mail is handled by 5 alt2.aspmx.l.google.com.
nmap.org mail is handled by 5 alt1.aspmx.l.google.com.
nmap.org mail is handled by 10 aspmx3.googlemail.com.

Enumerar todos los hosts

Para que este comando funcione, se debe ser el administrador del nodo, si se cumple esta condición, con el parámetro -l puedes obtener la información.

┌──(nato㉿kali)-[~]
└─$ host -l nmap.org 
Host nmap.org not found: 5(REFUSED)
; Transfer failed.

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