asnlookup

CLI and Go package for fast, offline ASN lookups.

A level compressed trie in array representation is used for achieving very fast lookups with a small memory footprint. The level compression is user-tunable between space-efficiency and time-efficiency. In LC-trie terms, the tuning adjusts the fill factor of the redundancy-enabled level compression.

Due to the array-represented trie and binary marshaling, the inflation of a pre-converted database can be measured in tens of milliseconds. In other words the CLI tool can even be used for one-off lookups without any perceivable startup slowness.

time asnlookup --db ~/.asnlookup.db 8.8.8.8
15169

real    0m0,027s
user    0m0,025s
sys     0m0,018s

Installation

Using prebuilt binaries:

curl -fsSL https://github.com/viktb/asnlookup/releases/download/v0.1.2/asnlookup-linux-amd64-v0.1.2.tar.gz | sudo tar -zx -C /usr/local/bin

From source:

go install github.com/viktb/asnlookup/cmd/asnlookup@latest
go install github.com/viktb/asnlookup/cmd/asnlookup-utils@latest

Usage

CLI

1. Download a fresh RIB dump, e.g. from http://archive.routeviews.org/:

   ./hack/pull_rib.sh
2. Convert it to asnlookup's own format:

   bzcat rib.*.bz2 | asnlookup-utils convert --input - --output /path/to/my.db
3. Use it with asnlookup:

   asnlookup --db /path/to/my.db 8.8.8.8
   or using the ASNLOOKUP_DB environment variable:

   export ASNLOOKUP_DB=/path/to/my.db
   asnlookup 8.8.8.8

Batch lookups

You may also do batch lookups for IPs provided to standard input using the --batch flag:

echo -ne '1.1.1.1\n8.8.8.8\n' | asnlookup --db ~/.asnlookup.db --batch
13335
15169

If you have tons of IPs to check, this will be a lot faster than inflating the multi-megabyte database each time asnlookup is invoked.

Go package

1. Build a database

   • Manually:

     builder := database.NewBuilder()
     
     _, prefix, _ := net.ParseCIDR("8.8.0.0/16")
     err := builder.InsertMapping(prefix, 420)
     if err != nil {
         panic(err)
     }
        
     db, err := builder.Build()
     if err != nil {
         panic(err)
     }

   • Using an MRT file:

     mrtFile, err := os.OpenFile("/path/to/file.mrt", os.O_RDONLY, 0)
     if err != nil {
         panic(err)
     }
     defer mrtFile.Close() 
     
     builder := database.NewBuilder()
     if err = builder.ImportMRT(mrtFile); err != nil {
         panic(err)
     }
     
     db, err := builder.Build()
     if err != nil {
         panic(err)
     }

   • Using a marshaled database (see asnlookup-utils convert):

     dbFile, err := os.OpenFile("/path/to/file.db", os.O_RDONLY, 0)
     if err != nil {
         panic(err)
     }
     defer dbFile.Close()
     
     db, err := database.NewFromDump(dbFile)
     if err != nil {
         panic(err)
     }

2. Look things up!

   as, err := db.Lookup(net.ParseIP("8.8.8.8"))
   if err != nil {
       panic(err)
   }
   fmt.Println(as.Number)