Максим, доюрый день.
Спасибо за ответ, попробую с новой стабильной версией из портов.

Чтобы не плодить темы:
Есть 2-й сервер, на нём установлена: FreeBSD 8.2-RELEASE-p3 amd64
nginx -V
nginx version: nginx/1.2.3 ( самая свежая версия из stable )
TLS SNI support enabled
configure arguments: --prefix=/usr/local/etc/nginx --with-cc-opt='-I /usr/local/include' --with-ld-opt='-L /usr/local/lib' --conf-path=/usr/local/etc/nginx/nginx.conf --sbin-path=/usr/local/sbin/nginx --pid-path=/var/run/nginx.pid --error-log-path=/var/log/nginx-error.log --user=www --group=www --with-debug --http-client-body-temp-path=/var/tmp/nginx/client_body_temp --http-fastcgi-temp-path=/var/tmp/nginx/fastcgi_temp --http-proxy-temp-path=/var/tmp/nginx/proxy_temp --http-scgi-temp-path=/var/tmp/nginx/scgi_temp --http-uwsgi-temp-path=/var/tmp/nginx/uwsgi_temp --http-log-path=/var/log/nginx-access.log --add-module=/usr/ports/www/nginx/work/agentzh-headers-more-nginx-module-6586984 --with-http_image_filter_module --add-module=/usr/ports/www/nginx/work/yaoweibin-ngx_http_substitutions_filter_module-27a01b3 --with-http_stub_status_module --with-pcre --with-http_ssl_module

В dmesg вижу:
id 63769 (nginx), uid 80: exited on signal 11
pid 63801 (nginx), uid 80: exited on signal 11 (core dumped)

gdb /usr/local/sbin/nginx nginx.core.63801
Loaded symbols for /libexec/ld-elf.so.1
#0 0x000000000040a350 in ngx_hash_find (hash=0x80240a868, key=34394151004, name=0x2 <Address 0x2 out of bounds>, len=7) at src/core/ngx_hash.c:34
34 src/core/ngx_hash.c: No such file or directory.
in src/core/ngx_hash.c

(gdb) bt
#0 0x000000000040a350 in ngx_hash_find (hash=0x80240a868, key=34394151004, name=0x2 <Address 0x2 out of bounds>, len=7) at src/core/ngx_hash.c:34
#1 0x000000000049e919 in ngx_http_proxy_create_request (r=0x801f57700) at src/http/modules/ngx_http_proxy_module.c:1040
#2 0x0000000000468b71 in ngx_http_upstream_init_request (r=0x801f57700) at src/http/ngx_http_upstream.c:505
#3 0x0000000000468904 in ngx_http_upstream_init (r=0x801f57700) at src/http/ngx_http_upstream.c:446
#4 0x000000000045ec83 in ngx_http_read_client_request_body (r=0x801f57700, post_handler=0x468820 <ngx_http_upstream_init>) at src/http/ngx_http_request_body.c:59
#5 0x000000000049da4c in ngx_http_proxy_handler (r=0x801f57700) at src/http/modules/ngx_http_proxy_module.c:702
#6 0x000000000044692d in ngx_http_core_content_phase (r=0x801f57700, ph=0x80265da68) at src/http/ngx_http_core_module.c:1396
#7 0x0000000000445462 in ngx_http_core_run_phases (r=0x801f57700) at src/http/ngx_http_core_module.c:877
#8 0x00000000004453dd in ngx_http_handler (r=0x801f57700) at src/http/ngx_http_core_module.c:860
#9 0x0000000000453d74 in ngx_http_process_request (r=0x801f57700) at src/http/ngx_http_request.c:1685
#10 0x0000000000452775 in ngx_http_process_request_headers (rev=0x80266d730) at src/http/ngx_http_request.c:1135
#11 0x0000000000451f06 in ngx_http_process_request_line (rev=0x80266d730) at src/http/ngx_http_request.c:933
#12 0x0000000000451108 in ngx_http_init_request (rev=0x80266d730) at src/http/ngx_http_request.c:519
#13 0x000000000042d3dc in ngx_event_process_posted (cycle=0x801e55050, posted=0x5f0a60) at src/event/ngx_event_posted.c:40
#14 0x000000000042ae85 in ngx_process_events_and_timers (cycle=0x801e55050) at src/event/ngx_event.c:274
#15 0x00000000004381c4 in ngx_worker_process_cycle (cycle=0x801e55050, data=0x0) at src/os/unix/ngx_process_cycle.c:808
#16 0x00000000004351c1 in ngx_spawn_process (cycle=0x801e55050, proc=0x437fd0 <ngx_worker_process_cycle>, data=0x0, name=0x4c18c9 "worker process", respawn=6) at src/os/unix/ngx_process.c:198
#17 0x0000000000437bf2 in ngx_reap_children (cycle=0x801e55050) at src/os/unix/ngx_process_cycle.c:622
#18 0x0000000000436946 in ngx_master_process_cycle (cycle=0x801e55050) at src/os/unix/ngx_process_cycle.c:181
#19 0x00000000004066d3 in main (argc=1, argv=0x7fffffffed68) at src/core/nginx.c:410

(gdb) bt full
#0 0x000000000040a350 in ngx_hash_find (hash=0x80240a868, key=34394151004, name=0x2 <Address 0x2 out of bounds>, len=7) at src/core/ngx_hash.c:34
i = 0
elt = (ngx_hash_elt_t *) 0x80232e890
#1 0x000000000049e919 in ngx_http_proxy_create_request (r=0x801f57700) at src/http/modules/ngx_http_proxy_module.c:1040
len = 1363
uri_len = 28
loc_len = 0
body_len = 0
escape = 0
b = (ngx_buf_t *) 0x0
method = {len = 4, data = 0x801e49800 "GET /images/auth.jpg HTTP/1.0\r\nX-Real-Remote-Addr"}
i = 0
unparsed_uri = 1
cl = (ngx_chain_t *) 0x0
body = (ngx_chain_t *) 0x0
part = (ngx_list_part_t *) 0x8027e2ca8
header = (ngx_table_elt_t *) 0x8027e3050
u = (ngx_http_upstream_t *) 0x8027e33e0
ctx = (ngx_http_proxy_ctx_t *) 0x8027e2df8
code = 0x100000000
e = {ip = 0x802200001 "л_", pos = 0x5fcd28 "(м_", sp = 0x0, buf = {len = 4294960124, data = 0x801e49820 " HTTP/1.0\r\nX-Real-Remote-Addr"}, line = {len = 34391496708,
data = 0x2 <Address 0x2 out of bounds>}, args = 0x989680 <Address 0x989680 out of bounds>, flushed = 0, skip = 0, quote = 0, is_args = 0, log = 0, status = 34401561808, request = 0x0}
le = {ip = 0x80232e720 "", pos = 0x0, sp = 0x1, buf = {len = 0, data = 0x800000000 <Address 0x800000000 out of bounds>}, line = {len = 1431655766, data = 0x0}, args = 0x0, flushed = 1,
skip = 0, quote = 0, is_args = 0, log = 0, status = 34391496707, request = 0x801f57700}
plcf = (ngx_http_proxy_loc_conf_t *) 0x80240a6d0
lcode = 0x465e20 <ngx_http_script_copy_len_code>
#2 0x0000000000468b71 in ngx_http_upstream_init_request (r=0x801f57700) at src/http/ngx_http_upstream.c:505
host = (ngx_str_t *) 0x801ee3000
i = 34401708392
ctx = (ngx_resolver_ctx_t *) 0x7fffffffe520
temp = {next = 0x0, resolver = 0x0, udp_connection = 0x0, ident = 140737488348336, state = 34393362520, type = 2, name = {len = 140737488348432, data = 0x7fffffffed78 "fОЪЪЪ\177"}, naddrs = 97,
addrs = 0x78, addr = 4294967273, handler = 0xe, data = 0x0, timeout = 37, quick = 18446744073709551614, recursion = 34414286640, event = 0x7fffffffe520}
cln = (ngx_http_cleanup_t *) 0x43ae9a
u = (ngx_http_upstream_t *) 0x8027e33e0
clcf = (ngx_http_core_loc_conf_t *) 0x20
uscf = (ngx_http_upstream_srv_conf_t *) 0xfffffffffffffffe
uscfp = (ngx_http_upstream_srv_conf_t **) 0x803405730
umcf = (ngx_http_upstream_main_conf_t *) 0x8027e2f98
#3 0x0000000000468904 in ngx_http_upstream_init (r=0x801f57700) at src/http/ngx_http_upstream.c:446
c = (ngx_connection_t *) 0x802806968
#4 0x000000000045ec83 in ngx_http_read_client_request_body (r=0x801f57700, post_handler=0x468820 <ngx_http_upstream_init>) at src/http/ngx_http_request_body.c:59
preread = 34401558528
size = 34401562264
b = (ngx_buf_t *) 0x8027e2000
cl = (ngx_chain_t *) 0x7fffffffe5d0
next = (ngx_chain_t **) 0x40995a
tf = (ngx_temp_file_t *) 0x100
rb = (ngx_http_request_body_t *) 0x8027e2f98
clcf = (ngx_http_core_loc_conf_t *) 0x0
#5 0x000000000049da4c in ngx_http_proxy_handler (r=0x801f57700) at src/http/modules/ngx_http_proxy_module.c:702
rc = 34391556392
u = (ngx_http_upstream_t *) 0x8027e33e0
ctx = (ngx_http_proxy_ctx_t *) 0x8027e2df8
plcf = (ngx_http_proxy_loc_conf_t *) 0x80240a6d0
#6 0x000000000044692d in ngx_http_core_content_phase (r=0x801f57700, ph=0x80265da68) at src/http/ngx_http_core_module.c:1396
root = 18446744073709551611
rc = 0
path = {len = 34399967824, data = 0x801f57700 "HTTP"}
#7 0x0000000000445462 in ngx_http_core_run_phases (r=0x801f57700) at src/http/ngx_http_core_module.c:877
rc = -2
ph = (ngx_http_phase_handler_t *) 0x80265d978
cmcf = (ngx_http_core_main_conf_t *) 0x801e56810
#8 0x00000000004453dd in ngx_http_handler (r=0x801f57700) at src/http/ngx_http_core_module.c:860
cmcf = (ngx_http_core_main_conf_t *) 0x80266d730
#9 0x0000000000453d74 in ngx_http_process_request (r=0x801f57700) at src/http/ngx_http_request.c:1685
c = (ngx_connection_t *) 0x802806968
#10 0x0000000000452775 in ngx_http_process_request_headers (rev=0x80266d730) at src/http/ngx_http_request.c:1135
p = (u_char *) 0x10 <Address 0x10 out of bounds>
len = 34401558528
n = 369
rc = 0
rv = 0
h = (ngx_table_elt_t *) 0x8027e3020
c = (ngx_connection_t *) 0x802806968
hh = (ngx_http_header_t *) 0x0
r = (ngx_http_request_t *) 0x801f57700
cscf = (ngx_http_core_srv_conf_t *) 0x801e73a50
cmcf = (ngx_http_core_main_conf_t *) 0x801e56810
#11 0x0000000000451f06 in ngx_http_process_request_line (rev=0x80266d730) at src/http/ngx_http_request.c:933
host = (u_char *) 0x8027e2000 "х/~\002\b"
n = 1024
rc = 0
rv = 624
c = (ngx_connection_t *) 0x802806968
r = (ngx_http_request_t *) 0x801f57700
cscf = (ngx_http_core_srv_conf_t *) 0x8027e2568
#12 0x0000000000451108 in ngx_http_init_request (rev=0x80266d730) at src/http/ngx_http_request.c:519
tp = (ngx_time_t *) 0x5ee490
i = 0
c = (ngx_connection_t *) 0x802806968
r = (ngx_http_request_t *) 0x801f57700
sin = (struct sockaddr_in *) 0x802279520
port = (ngx_http_port_t *) 0x80265ea90
addr = (ngx_http_in_addr_t *) 0x80265eaa0
ctx = (ngx_http_log_ctx_t *) 0x8022794a0
addr_conf = (ngx_http_addr_conf_t *) 0x80265eaa8
hc = (ngx_http_connection_t *) 0x8022794b8
cscf = (ngx_http_core_srv_conf_t *) 0x801e73a50
clcf = (ngx_http_core_loc_conf_t *) 0x801e73ae8
cmcf = (ngx_http_core_main_conf_t *) 0x801e56810
#13 0x000000000042d3dc in ngx_event_process_posted (cycle=0x801e55050, posted=0x5f0a60) at src/event/ngx_event_posted.c:40
ev = (ngx_event_t *) 0x80266d730
#14 0x000000000042ae85 in ngx_process_events_and_timers (cycle=0x801e55050) at src/event/ngx_event.c:274
flags = 3
timer = 2428
delta = 1
#15 0x00000000004381c4 in ngx_worker_process_cycle (cycle=0x801e55050, data=0x0) at src/os/unix/ngx_process_cycle.c:808
i = 1
c = (ngx_connection_t *) 0x7fffffffe990
#16 0x00000000004351c1 in ngx_spawn_process (cycle=0x801e55050, proc=0x437fd0 <ngx_worker_process_cycle>, data=0x0, name=0x4c18c9 "worker process", respawn=6) at src/os/unix/ngx_process.c:198
on = 1
pid = 0
s = 6
#17 0x0000000000437bf2 in ngx_reap_children (cycle=0x801e55050) at src/os/unix/ngx_process_cycle.c:622
i = 6
n = 8
---Type <return> to continue, or q <return> to quit---
live = 1
ch = {command = 2, pid = 63768, slot = 6, fd = -1}
ccf = (ngx_core_conf_t *) 0x505f6694
#18 0x0000000000436946 in ngx_master_process_cycle (cycle=0x801e55050) at src/os/unix/ngx_process_cycle.c:181
title = 0x80265ff9c "master process /usr/local/sbin/nginx"
p = (u_char *) 0x80265ffc0 ""
size = 37
i = 1
n = 6
sigio = 0
set = {__bits = {0, 0, 0, 0}}
itv = {it_interval = {tv_sec = 0, tv_usec = 0}, it_value = {tv_sec = 0, tv_usec = 0}}
live = 1
delay = 0
ls = (ngx_listening_t *) 0x6
ccf = (ngx_core_conf_t *) 0x801e56040
#19 0x00000000004066d3 in main (argc=1, argv=0x7fffffffed68) at src/core/nginx.c:410
i = 52
log = (ngx_log_t *) 0x5ee040
cycle = (ngx_cycle_t *) 0x801e55050
init_cycle = {conf_ctx = 0x0, pool = 0x801e49800, log = 0x5ee040, new_log = {log_level = 0, file = 0x0, connection = 0, handler = 0, data = 0x0, action = 0x0}, files = 0x0,
free_connections = 0x0, free_connection_n = 0, reusable_connections_queue = {prev = 0x0, next = 0x0}, listening = {elts = 0x0, nelts = 0, size = 0, nalloc = 0, pool = 0x0}, pathes = {elts = 0x0,
nelts = 0, size = 0, nalloc = 0, pool = 0x0}, open_files = {last = 0x0, part = {elts = 0x0, nelts = 0, next = 0x0}, size = 0, nalloc = 0, pool = 0x0}, shared_memory = {last = 0x0, part = {
elts = 0x0, nelts = 0, next = 0x0}, size = 0, nalloc = 0, pool = 0x0}, connection_n = 0, files_n = 0, connections = 0x0, read_events = 0x0, write_events = 0x0, old_cycle = 0x0, conf_file = {
len = 31, data = 0x4bda50 "/usr/local/etc/nginx/nginx.conf"}, conf_param = {len = 0, data = 0x0}, conf_prefix = {len = 21, data = 0x4bda50 "/usr/local/etc/nginx/nginx.conf"}, prefix = {len = 21,
data = 0x4bda38 "/usr/local/etc/nginx/"}, lock_file = {len = 0, data = 0x0}, hostname = {len = 0, data = 0x0}}
ccf = (ngx_core_conf_t *) 0x801e56040