After upgrading R8000 to 19.07.0 from 18.06.2 I noticed regular connect/disconnect messages in my debian postfix mail.log. These occur at the 'check' interval of haproxy for the postfix back end. These messages weren't occurring when running 18.06.2.
If I remove the 'check' option from haproxy config, the connect/disconnect log entries stop.
As a test, I set up haproxy on a CentOS 7 VM, copying the my haproxy config from OpenWRT, with the 'check' option enabled. This test did not cause connect/disconnect messages in the debian postfix log.
I ran tcpdump to have a look at the 'check' traffic. Seems to show 19.07 is sending extra traffic, possibly through the send-proxy path.
Some examples below.
10.0.0.1 OpenWRT haproxy
10.0.0.2 Debian postfix
10.0.0.3 CentOS haproxy
OpenWRT
23:44:26.605435 IP 10.0.0.1.48550 > 10.0.0.2.25: Flags [S], seq 191138336, win 29200, options [mss 1460,sackOK,TS val 450260067 ecr 0,nop,wscale 4], length 0
23:44:26.605471 IP 10.0.0.2.25 > 10.0.0.1.48550: Flags [S.], seq 4134356420, ack 191138337, win 28960, options [mss 1460,sackOK,TS val 477877981 ecr 450260067,nop,wscale 6], length 0
23:44:26.606059 IP 10.0.0.1.48550 > 10.0.0.2.25: Flags [P.], seq 1:44, ack 1, win 1825, options [nop,nop,TS val 450260068 ecr 477877981], length 43: SMTP: PROXY TCP4 10.0.0.1 10.0.0.2 48550 25
23:44:26.606087 IP 10.0.0.2.25 > 10.0.0.1.48550: Flags [.], ack 44, win 453, options [nop,nop,TS val 477877982 ecr 450260068], length 0
23:44:26.606103 IP 10.0.0.1.48550 > 10.0.0.2.25: Flags [R.], seq 44, ack 1, win 1825, options [nop,nop,TS val 450260068 ecr 477877981], length 0
23:44:26.606345 IP 10.0.0.1.48550 > 10.0.0.2.25: Flags [R], seq 191138380, win 0, length 0
CentOS
23:48:16.069296 IP 10.0.0.3.33202 > 10.0.0.2.25: Flags [S], seq 3996052808, win 29200, options [mss 1460,sackOK,TS val 1536468 ecr 0,nop,wscale 7], length 0
23:48:16.073476 IP 10.0.0.2.25 > 10.0.0.3.33202: Flags [S.], seq 1819759409, ack 3996052809, win 65160, options [mss 1460,sackOK,TS val 2967147940 ecr 1536468,nop,wscale 6], length 0
23:48:16.073617 IP 10.0.0.3.33202 > 10.0.0.2.25: Flags [R.], seq 1, ack 1, win 229, options [nop,nop,TS val 1536472 ecr 2967147940], length 0
section of haproxy config for postfix send-proxy
listen my_smtp4
bind 0.0.0.0:25
mode tcp
timeout client 1m
log global
option tcplog
option tcp-check
server postfix 10.0.0.2:25 send-proxy check inter 10000
# server postfix 10.0.0.2:25 send-proxy
Perhaps I might need to change something in haproxy.cfg for 19.07 ?
[ I tried changing 'bind 0.0.0.0:25' to 'bind 10.0.0.1:25' but it made no difference when 'check' enabled - I still get the connect/disconnect postfix log entries ]
regards,
Geof