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). ]
