Dear Dominic, Dominic Raferd <domi...@timedicer.co.uk> writes:
> On 08/05/2022 11:59, Byung-Hee HWANG wrote: >> Dear Bastian, >> >> Bastian Blank <bastian+postfix-users=postfix....@waldi.eu.org> writes: >> >>> Hi >>> >>> On Sun, May 08, 2022 at 07:42:00PM +0900, Byung-Hee HWANG wrote: >>>> May 8 10:24:25 bionic190316003 postfix/smtpd[10918]: warning: >>>> 17.188.51.209.list.dnswl.org: RBL lookup error: Host or domain name >>>> not found. Name service error for name=17.188.51.209.list.dnswl.org >>>> type=A: Host not found, try again >>>> As shown above log, the line 'RBL lookup error' is normal? Can i >>>> ignore that? >>> No, this line is not normal. It means you have an error in the DNS >>> resolution. Maybe you are using a public resolver. >> Thanks for quick reply Bastian! >> >> Below is my /etc/resolv.conf: >> >> #+begin_src text (/etc/resolv.conf in Google Compute Engine) >> soyeomul@bionic190316003:~$ sudo cat /etc/resolv.conf >> # This file is managed by man:systemd-resolved(8). Do not edit. >> # >> # This is a dynamic resolv.conf file for connecting local clients to the >> # internal DNS stub resolver of systemd-resolved. This file lists all >> # configured search domains. >> # >> # Run "systemd-resolve --status" to see details about the uplink DNS servers >> # currently in use. >> # >> # Third party programs must not access this file directly, but only >> through the >> # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a >> different way, >> # replace this symlink by a static file or a different symlink. >> # >> # See man:systemd-resolved.service(8) for details about the supported modes >> of >> # operation for /etc/resolv.conf. >> >> nameserver 127.0.0.53 >> options edns0 >> search us-west1-b.c.elite-flow-234711.internal >> c.elite-flow-234711.internal google.internal >> soyeomul@bionic190316003:~$ >> #+end_src >> >> Possibly i would like to solve this problem. >> >> Thanks! >> >> Sincerely, Linux fan Byung-Hee >> > I think your system is using systemd-resolved for DNS lookups; this > hands off the real work of resolving to public resolvers, so RBLs will > block your lookups. This is a normal setup for a systemd-based distro > but is not appropriate for a mail server. > > First install a true local resolver such as bind9 or unbound and then > switch your system to use it instead of systemd-resolved. To switch to > bind9 you could try my > https://www.timedicer.co.uk/programs/help/bind9-resolved-switch.sh.php. > > [ If you want, bind9 can be set so that 'normal' lookups still go via > external (public) resolvers (as you specify in > /etc/bind/named.conf.options), but lookups for RBLs are routed > directly. Perhaps unbound can do the same (I haven't tried it). ] Wow it seems so difficult work! I need time to think! Thanks for your kind advice!! Thanks again... Dominic ^^^ Sincerely, Linux fan Byung-Hee -- ^고맙습니다 _白衣從軍_ 감사합니다_^))//
