Introducing Mr. Netops's nifty inline resolver

If you have ever needed to resolve hostnames or ip address in arbitrarily formatted data, nir is the script for you.

Mr. Netops's nifty inline resolver (https://github.com/mrnetops/nir) will detect the following types of values

• Hostnames
• IPv4 Addresses
• IPv6 Addresses

in arbitrarily formatted data from standard in and will perform inline resolution including

• Hostnames
• IPv4 Addresses
• IPv6 Addresses
• getaddrinfo canonname

Some trivial examples

$ echo "fi fi fo www.google.com fum" | nir
fi fi fo www.google.com[216.58.216.36,2607:f8b0:4007:805::1012] fum

$ echo "www.google.com216.58.216.36" | nir
www.google.com[216.58.216.4,2607:f8b0:4007:809::2004]216.58.216.36[lax02s22-in-f4.1e100.net]

How about something a little more fun?

$ dig facebook.com ANY | nir

; <<>> DiG 9.9.5-3ubuntu0.1-Ubuntu <<>> facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1] ANY
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55201
;; flags: qr rd ra; QUERY: 1, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].INANY

;; ANSWER SECTION:
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].21599INNSa.ns.facebook.com[69.171.239.12].
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].21599INNSb.ns.facebook.com[69.171.255.12].
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].21599INTXTv=spf1 redirect=_spf.facebook.com
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].299INMX10 msgin.vvv.facebook.com[173.252.113.23].
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].119INSOAa.ns.facebook.com[69.171.239.12]. dns.facebook.com[31.13.70.1,2a03:2880:f00d:1:face:b00c:0:1,star.c10r.facebook.com]. 1423476020 7200 1800 604800 120
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].899INA173.252.120.6[edge-star-shv-12-frc3.facebook.com]
facebook.com[173.252.120.6,2a03:2880:2130:cf05:face:b00c:0:1].899INAAAA2a03:2880:2130:cf05:face:b00c:0:1[edge-star6-shv-12-frc3.facebook.com]

;; Query time: 48 msec
;; SERVER: 8.8.8.8[google-public-dns-a.google.com]#53(8.8.8.8[google-public-dns-a.google.com])
;; WHEN: Mon Feb 09 02:04:07 PST 2015
;; MSG SIZE  rcvd: 232

Ever wondered if your ip addresses and hostnames are really going where you think they are?

Great for checking

• Firewall configs
• Load balancer configs
• Any kind of network config really
• Dns zone files
• Application configs
• Arp output
• /etc/hosts

The list goes on.

For example

cat someConfig | nir
pool public {
      ipAddress1[hostname1]
      ipAddress2[wrongHostname]
      ipAddress3[hostname3]
}

object-group network host_name_4
 network-object host ipAddress4[wrongHostname]

or

cat someConfig | nir
pool public {
      hostname1[ipAddress1]
      hostname2[wrongSubnetIp]
      hostname3[ipAddress3]
}

You can chain nir to inspect forward and reverse lookup

$ echo "www.amazon.com" | nir | nir
www.amazon.com[176.32.98.166][205.251.242.103[s3-console-us-standard.console.aws.amazon.com]]

Usage information from nir --help

Mr. Netops's nifty inline resolver

Options:

      -format <format>
            Specify alternate formatting for resolved values
      -separator <separator>
            Specify alternate separator for lookups with multiple values
      -tags
            Add type tags to resolved values
      -verbose
            Print additional status information to stderr
      -debug
            Print debugging information to stderr
      -timeout <timeout>
            Dns lookup timeout
      -lookup <types>
            Types of resolved values and their presentation order
            Supports The following types: hostname, ipv4, ipv6, canonname
      -help
            This

Advanced Options:

      -hostnameRegexp <regexp>
            Specify an alternate hostname regular expression
      -ipV4AddressRegexp <regexp>
            Specify an alternate ipv4 address regular expression
      -ipV6AddressRegexp <regexp>
            Specify an alternate ipv6 address regular expression
      -ipV6Support
            Manually enable ipv6 support
      -noipV6Support
            Manually disable ipv6 support

Examples:

      Basic invocation
            someCommand | nir

      Present ipv4 & ipv6 resolved values in that order
            someCommand | nir -lookup ipv4,ipv6

      Format inline lookups in curly braces and seperate values with ;
            someCommand | nir -format '{%s}' -separator ';'

Use Cases:
                  
      dig facebook.com ANY | nir
      mtr -wr facebook.com | nir
      cat /etc/hosts | nir
      arp -a | nir