Net::Server sockets are not opened, why ?

[Wladimir Mutel]

	Dear all,

	I am using amavisd-new 2.11.0 as shipped with Ubuntu 18.04, with added 
configuration changes from https://www.iredmail.org/
	After recent reboot of my system, I noticed that postfix 
3.3.0-1ubuntu0.1 is unable to contact queue filter at localhost:10024 , 
and lsof -n does not show any process listening on this port. I set 
$log_level = 4; in /etc/amavis/conf.d/50-user and I see this in the log 
(after amavis service restart):

лис 13 22:13:41 smart amavis[10833]: Net::Server: Accept failed with 28 
tries left: Invalid argument
...
лис 13 22:14:08 smart amavis[10833]: Net::Server: Accept failed with 1 
tries left: Invalid argument
лис 13 22:14:09 smart amavis[10833]: Net::Server: Accept failed with 0 
tries left: Invalid argument
лис 13 22:14:10 smart amavis[10833]: Net::Server: Ran out of accept retries!

	Overall it looks like sockets are created but not put into 'listen'ing 
state, so 'accept' calls on them fail.
	I tried to follow the logic of socket initialization in amavisd-new and 
Net/Server.pm sources but I could not reach any definite conclusion so 
far. I suspect there could be some accidental changes in combination of 
bind address and listen socket numbers but I am not sure I got to the 
proper places in Net/Server* sources.

	So I would ask someone competent who encountered this behavior, how 
should I fix that ?

	iRedMail sets $inet_socket_port = [10024, 10026, 9998]; in 
/etc/amavis/conf.d/50-user
	I have ipv4 & ipv6 (6to4) enabled on my server which could impact bind 
address selection.
	@listen_sockets array is clearly non-empty
	And then, Amavis->new is constructed, as a derived class from 
Net::Server, and passes it 'port'=>\@listen_sockets and 
'host'=>$bind_to[0] parameters, and after that I could not trace it any 
deeper. I see this in the logs :

лис 13 17:03:08 smart amavis[5825]: will bind to 
/var/lib/amavis/amavisd.sock|unix, 127.0.0.1:10024/tcp, 
127.0.0.1:10026/tcp, 127.0.0.1:9998/tcp
лис 13 17:03:08 smart amavis[5834]: sd_notify (no socket): 
MAINPID=5834\nSTATUS=Daemonized, preparing to bind sockets.
лис 13 17:03:08 smart amavis[5834]: Net::Server: Binding to UNIX socket 
file "/var/lib/amavis/amavisd.sock"
лис 13 17:03:08 smart amavis[5834]: Net::Server: Binding to TCP port 
10024 on host 127.0.0.1 with IPv4
лис 13 17:03:08 smart amavis[5834]: Net::Server: Binding to TCP port 
10026 on host 127.0.0.1 with IPv4
лис 13 17:03:08 smart amavis[5834]: Net::Server: Binding to TCP port 
9998 on host 127.0.0.1 with IPv4

	But how can I be sure that 'listen' return code is properly checked in 
Perl sources ? and that 'listen' call is not bypassed due to some 
accidental condition ?

	Thank you in advance for your responses. I can provide you 'sudo' 
access on my host and the right to change any related configs and to 
restart any needed services or the whole system.