[SR-Users] unable to receive UDP

After 4 (long) days of trying to receive any UDP SIP, I'm hoping someone can point out what I'm doing wrong. I've looked at the kamailio code. I'm beginning to think it's the 'polling' code, but it looks fine. It could be Centos or a Dell network driver, but not seeing any errors anywhere. - stock build/compile...   Version: kamailio 5.5.2 (x86_64/linux) 0d53d9   Compile flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES   MAX_RECV_BUFFER_SIZE=262144   MAX_URI_SIZE=1024   BUF_SIZE=65535   DEFAULT PKG_SIZE=8MB   DEFAULT SHM_SIZE=64MB   ADAPTIVE_WAIT_LOOPS=1024   TCP poll methods: poll, epoll_lt, epoll_et, sigio_rt, select   Source code revision ID: 0d53d9   Compiled with: gcc 4.8.5   Compiled architecture: x86_64   Compiled on: 08:44:19 Oct 11 2021 Running Centos 7 all updated. Dell R630. # sestatus SELinux status:                 disabled # firewall-cmd --list-all   ports: 5666/tcp 873/tcp 873/udp 80/tcp 443/tcp 5060/tcp 5060/udp 5061/tcp 5061/udp - Just trying to send SIP INVITE from trunk provider to R630 kamailio... (SIP trunk) UDP 172.200.200.202:5060 -> (firewall) UDP 172.250.250.162:5060 -> 1:1 NAT -> (R630) UDP 10.102.88.81:5060 - I can 'see' the packet hit the em3 network... #  tcpdump -i em3 -e -vv -n port 5060 11:53:33.260892 99:99:ef:3e:69:c1 > 99:99:1c:48:4e:e3, ethertype IPv4 (0x0800), length 1366: (tos 0x0, ttl 54, id 20430, offset 0, flags [none], proto UDP (17), length 1352)     172.200.200.202.sip > 10.102.88.81.sip: [udp sum ok] SIP, length: 1324     INVITE sip:+18005551234@172.250.250.162:5060 SIP/2.0     ... At this point, I just need to see a SIP INVITE received. Then I can go back to working on a real config. I've tried with TCP on/off, listening on all networks, alias on/off, strace and everything else I could think of.Truly appreciate any guidance. Tried every sample config possible, but I just need to test receiving the SIP UDP packet, so this 'should' be minimum config... #!KAMAILIO debug=9 log_stderror=no log_facility=LOG_LOCAL0 log_prefix="{$mt $hdr(CSeq) $ci} " children=2 disable_tcp=yes udp4_raw=on auto_aliases=no alias="sbc01.mysite.com" listen=udp:10.102.88.81:5060 loadmodule "debugger.so" loadmodule "jsonrpcs.so" loadmodule "kex.so" loadmodule "corex.so" loadmodule "sl.so" loadmodule "rr.so" loadmodule "pv.so" loadmodule "textops.so" loadmodule "siputils.so" loadmodule "xlog.so" loadmodule "sanity.so" loadmodule "ctl.so" loadmodule "cfg_rpc.so" modparam("debugger", "cfgtrace", 1) request_route {   xlog("SIP received xxxxxxxxxxxxxxxxxxx\n"); } # kamcmd ps 11578    main process - attendant 11579    udp receiver child=0 sock=10.102.88.81:5060 11580    udp receiver child=1 sock=10.102.88.81:5060 11581    slow timer 11583    timer 11584    secondary timer 11585    JSONRPCS FIFO 11586    JSONRPCS DATAGRAM 11587    ctl handler - I get plenty of logging, but the logging just waits here... Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: INFO: ctl [io_listener.c:210]: io_listen_loop(): io_listen_loop: using epoll_lt as the io watch method (auto detected) Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: <core> [core/mem/q_malloc.c:374]: qm_malloc(): qm_malloc(0x7fd2a8bae010, 4800) called from core: core/io_wait.c: init_io_wait(469) Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10059]: DEBUG: <core> [core/mem/q_malloc.c:419]: qm_malloc(): qm_malloc(0x7fd2a8bae010, 65456) returns address 0x7fd2a8c652d8 frag. 0x7fd2a8c652a0 (size=65456) on 1 -th hit Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: <core> [core/mem/q_malloc.c:419]: qm_malloc(): qm_malloc(0x7fd2a8bae010, 4800) returns address 0x7fd2a8c652d8 frag. 0x7fd2a8c652a0 (size=4800) on 1 -th hit Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: <core> [core/mem/q_malloc.c:374]: qm_malloc(): qm_malloc(0x7fd2a8bae010, 2400) called from core: core/io_wait.c: init_io_wait(516) Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: <core> [core/mem/q_malloc.c:419]: qm_malloc(): qm_malloc(0x7fd2a8bae010, 2400) returns address 0x7fd2a8c66600 frag. 0x7fd2a8c665c8 (size=2400) on 1 -th hit Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: ctl [io_listener.c:246]: io_listen_loop(): io_listen_loop: adding socket 8, type 2, transport 3 (/var/run/kamailio//kamailio_ctl) Oct 12 11:38:04 sbc01 /usr/local/sbin/kamailio[10060]: DEBUG: ctl [../../core/io_wait.h:375]: io_watch_add(): DBG: io_watch_add(0x7fd2a70a5360, 8, 2, 0x2439960), fd_no=0 - The only other thing that I see is transport 3. Isn't that a UNIXS_SOCK?