When load balancing to two exchange servers Haproxy use its proper address when connecting. This results in a reset on exchange.
I have used different combinations of commands, accept-proxy, send-proxy etc but no success so far. I am beginning to suspect that this is a bug, if not anything is missing in the haproxy installation.
Here is the results of haproxy -vv
HAProxy version 2.7.1-1ppa1~jammy 2022/12/19 - https://haproxy.org/
Status: stable branch - will stop receiving fixes around Q1 2024.
Known bugs: http://www.haproxy.org/bugs/bugs-2.7.1.html
Running on: Linux 5.15.0-58-generic #64-Ubuntu SMP Thu Jan 5 11:43:13 UTC 2023 x86_64
Build options :
TARGET = linux-glibc
CPU = generic
CC = cc
CFLAGS = -O2 -g -O2 -flto=auto -ffat-lto-objects -flto=auto -ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -Wall -Wextra -Wundef -Wdeclaration-after-statement -Wfatal-errors -Wtype-limits -Wshift-negative-value -Wshift-overflow=2 -Wduplicated-cond -Wnull-dereference -fwrapv -Wno-address-of-packed-member -Wno-unused-label -Wno-sign-compare -Wno-unused-parameter -Wno-clobbered -Wno-missing-field-initializers -Wno-cast-function-type -Wno-string-plus-int -Wno-atomic-alignment
OPTIONS = USE_PCRE2=1 USE_PCRE2_JIT=1 USE_OPENSSL=1 USE_LUA=1 USE_SLZ=1 USE_SYSTEMD=1 USE_OT=1 USE_PROMEX=1
DEBUG = -DDEBUG_STRICT -DDEBUG_MEMORY_POOLS
Feature list : +EPOLL -KQUEUE +NETFILTER -PCRE -PCRE_JIT +PCRE2 +PCRE2_JIT +POLL +THREAD -PTHREAD_EMULATION +BACKTRACE -STATIC_PCRE -STATIC_PCRE2 +TPROXY +LINUX_TPROXY +LINUX_SPLICE +LIBCRYPT +CRYPT_H -ENGINE +GETADDRINFO +OPENSSL -OPENSSL_WOLFSSL +LUA +ACCEPT4 -CLOSEFROM -ZLIB +SLZ +CPU_AFFINITY +TFO +NS +DL +RT -DEVICEATLAS -51DEGREES -WURFL +SYSTEMD -OBSOLETE_LINKER +PRCTL -PROCCTL +THREAD_DUMP -EVPORTS +OT -QUIC +PROMEX -MEMORY_PROFILING +SHM_OPEN
Default settings :
bufsize = 16384, maxrewrite = 1024, maxpollevents = 200
Built with multi-threading support (MAX_TGROUPS=16, MAX_THREADS=256, default=2).
Built with OpenSSL version : OpenSSL 3.0.2 15 Mar 2022
Running on OpenSSL version : OpenSSL 3.0.2 15 Mar 2022
OpenSSL library supports TLS extensions : yes
OpenSSL library supports SNI : yes
OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2 TLSv1.3
OpenSSL providers loaded : default
Built with Lua version : Lua 5.3.6
Built with the Prometheus exporter as a service
Built with network namespace support.
Built with OpenTracing support.
Support for malloc_trim() is enabled.
Built with libslz for stateless compression.
Compression algorithms supported : identity("identity"), deflate("deflate"), raw-deflate("deflate"), gzip("gzip")
Built with transparent proxy support using: IP_TRANSPARENT IPV6_TRANSPARENT IP_FREEBIND
Built with PCRE2 version : 10.39 2021-10-29
PCRE2 library supports JIT : yes
Encrypted password support via crypt(3): yes
Built with gcc compiler version 11.3.0
Available polling systems :
epoll : pref=300, test result OK
poll : pref=200, test result OK
select : pref=150, test result OK
Total: 3 (3 usable), will use epoll.
Available multiplexer protocols :
(protocols marked as <default> cannot be specified using 'proto' keyword)
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|HOL_RISK|NO_UPG
fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG
h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG
<default> : mode=HTTP side=FE|BE mux=H1 flags=HTX
none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG
<default> : mode=TCP side=FE|BE mux=PASS flags=
Available services : prometheus-exporter
Available filters :
[BWLIM] bwlim-in
[BWLIM] bwlim-out
[CACHE] cache
[COMP] compression
[FCGI] fcgi-app
[ OT] opentracing
[SPOE] spoe
[TRACE] trace
And here is my config at the moment
global
maxconn 100000
spread-checks 4
defaults
log global
mode tcp
timeout connect 5000ms
timeout client 50000ms
timeout server 50000ms
frontend fe_smtp
bind *:25 accept-proxy
mode tcp
default_backend ex_smtp
backend ex_smtp
mode tcp
balance roundrobin
server smtp1 10.0.0.1:25 check send-proxy
server smtp2 10.0.0.2:25 check send-proxy
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