今まで，ログに残る変な IP を調べる時「IP 検索」のサイトを利用していた．
が，もう少し手軽に利用できないものかと…

検索すると，wiki WHOIS
さらに，【 whois 】コマンド――ドメイン情報を表示する

Linux のコマンドであれば，Synology NAS でも可能と思い試してみることに．

Iwao@DS116:~$ sudo -i
Password:
root@DS116:~# opkg update
-ash: opkg: command not found
root@DS116:~# cd /var/services/homes/Iwao/
root@DS116:/var/services/homes/Iwao# source ./set_ds_inc.sh
root@DS116:/var/services/homes/Iwao# opkg -v
opkg version 0.1.8
root@DS116:/var/services/homes/Iwao# opkg update
Downloading http://pkg.entware.net/binaries/armv7/Packages.gz
Updated list of available packages in /opt/var/opkg-lists/packages
root@DS116:/var/services/homes/Iwao# opkg install whois
Installing whois (5.2.19-1) to root...
Downloading http://pkg.entware.net/binaries/armv7/whois_5.2.19-1_armv7soft.ipk
Installing libidn (1.33-2) to root...
Downloading http://pkg.entware.net/binaries/armv7/libidn_1.33-2_armv7soft.ipk
Configuring libidn.
Configuring whois.
root@DS116:/var/services/homes/Iwao# whois
Usage: whois [OPTION]... OBJECT...

-h HOST, --host HOST   connect to server HOST
-p PORT, --port PORT   connect to PORT
-H                     hide legal disclaimers
      --verbose        explain what is being done
      --help           display this help and exit
      --version        output version information and exit

These flags are supported by whois.ripe.net and some RIPE-like servers:
-l                     find the one level less specific match
-L                     find all levels less specific matches
-m                     find all one level more specific matches
-M                     find all levels of more specific matches
-c                     find the smallest match containing a mnt-irt attribute
-x                     exact match
-b                     return brief IP address ranges with abuse contact
-B                     turn off object filtering (show email addresses)
-G                     turn off grouping of associated objects
-d                     return DNS reverse delegation objects too
-i ATTR[,ATTR]...      do an inverse look-up for specified ATTRibutes
-T TYPE[,TYPE]...      only look for objects of TYPE
-K                     only primary keys are returned
-r                     turn off recursive look-ups for contact information
-R                     force to show local copy of the domain object even
                       if it contains referral
-a                     also search all the mirrored databases
-s SOURCE[,SOURCE]...  search the database mirrored from SOURCE
-g SOURCE:FIRST-LAST   find updates from SOURCE from serial FIRST to LAST
-t TYPE                request template for object of TYPE
-v TYPE                request verbose template for object of TYPE
-q [version|sources|types]  query specified server info
root@DS116:/var/services/homes/Iwao#

そのままでは Cannot open /opt/etc/whois.conf: Permission denied となる．

Iwao@DS116:~$ whois 27.92.169.109
Cannot open /opt/etc/whois.conf: Permission denied
Iwao@DS116:~$ sudo -i
Password:
root@DS116:~# cd /opt/etc/
root@DS116:/opt/etc# ll
total 28
drwxr-xr-x  3 root root 4096 Dec 28 10:55 .
drwxr-xr-x 11 root root 4096 Jan  4  2018 ..
drwxr-xr-x  2 root root 4096 Sep 25  2017 init.d
-rw-r--r--  1 root root    0 May 31  2017 ld.so.conf
-rw-r--r--  1 root root  282 May 31  2017 nsswitch.conf
-rw-r--r--  1 root root  142 Aug 16  2016 opkg.conf
-rwxr-xr-x  1 root root  471 May 31  2017 profile
-rw-------  1 root root  526 Jan  4  2018 whois.conf
root@DS116:/opt/etc# chmod 644 whois.conf
root@DS116:/opt/etc# exit
logout
Iwao@DS116:~$ whois 27.92.169.109
% [whois.apnic.net]
% Whois data copyright terms    http://www.apnic.net/db/dbcopyright.html

% Information related to '27.80.0.0 - 27.95.255.255'

% Abuse contact for '27.80.0.0 - 27.95.255.255' is 'hostmaster@nic.ad.jp'

inetnum:        27.80.0.0 - 27.95.255.255

...

last-modified:  2011-03-01T18:11:04Z
source:         JPNIC

% This query was served by the APNIC Whois Service version 1.88.15-46 (WHOIS-JP4)


Iwao@DS116:~$