sergey-safarov left a comment (kamailio/kamailio#4187)
To reproduce this issue, you need to start Kamailio with config file ``` listen=eth0
tcp_send_timeout=3
loadmodule "xlog.so" loadmodule "pv.so" loadmodule "ctl.so" loadmodule "jsonrpcs.so" loadmodule "tm.so"
loadmodule "dispatcher.so" modparam("dispatcher", "list_file", "/tmp/dispatcher.list") modparam("dispatcher", "ds_ping_from", "sip:proxy@aggregator.nga911.com") modparam("dispatcher", "ds_ping_interval", 3) modparam("dispatcher", "ds_probing_mode", 1)
route{ xerr("SDP: TEST $tu\n"); drop; } ``` Where `/tmp/dispatcher.list` has content ``` 1 sip:sip.telnyx.com:5060;transport=tcp 8 ``` In another window, you need to start tcpdump using the command ``` tcpdump -ni any host sip.telnyx.com ``` Imdediately after start you will see something like ``` root@nout:~# tcpdump -ni any host sip.telnyx.com tcpdump: WARNING: any: That device doesn't support promiscuous mode (Promiscuous mode not supported on the "any" device) dropped privs to tcpdump tcpdump: verbose output suppressed, use -v[v]... for full protocol decode listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
13:47:57.761479 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [S], seq 105320156, win 64240, options [mss 1460,sackOK,TS val 2910270166 ecr 0,nop,wscale 7], length 0 13:47:57.961010 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [S.], seq 3545220477, ack 105320157, win 65160, options [mss 1370,sackOK,TS val 1818499729 ecr 2910270166,nop,wscale 7], length 0 13:47:57.961211 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 1:428, ack 1, win 502, options [nop,nop,TS val 2910270365 ecr 1818499729], length 427 13:47:58.312923 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 428, win 506, options [nop,nop,TS val 1818499928 ecr 2910270365], length 0 13:47:58.312930 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 1:445, ack 428, win 506, options [nop,nop,TS val 1818499932 ecr 2910270365], length 444 13:47:58.353207 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [.], ack 445, win 501, options [nop,nop,TS val 2910270758 ecr 1818499932], length 0
13:48:00.760881 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 428:855, ack 445, win 501, options [nop,nop,TS val 2910273165 ecr 1818499932], length 427 13:48:00.960459 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 855, win 503, options [nop,nop,TS val 1818502729 ecr 2910273165], length 0 13:48:00.960461 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 445:889, ack 855, win 503, options [nop,nop,TS val 1818502729 ecr 2910273165], length 444 13:48:00.960529 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [.], ack 889, win 498, options [nop,nop,TS val 2910273365 ecr 1818502729], length 0
13:48:03.760894 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 855:1282, ack 889, win 501, options [nop,nop,TS val 2910276165 ecr 1818502729], length 427 13:48:04.100711 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 1282, win 501, options [nop,nop,TS val 1818505728 ecr 2910276165], length 0 13:48:04.100712 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 889:1333, ack 1282, win 501, options [nop,nop,TS val 1818505729 ecr 2910276165], length 444 13:48:04.100781 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [.], ack 1333, win 498, options [nop,nop,TS val 2910276505 ecr 1818505729], length 0 ``` Then, you need to execute the iptables command ``` iptables -I INPUT -s 192.76.120.10/32 -j DROP ``` Then tcpdump output will be like ``` 13:49:12.760855 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910345165 ecr 1818571754], length 427 13:49:13.200228 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910345605 ecr 1818571754], length 427 13:49:13.213592 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818574958 ecr 2910345165], length 444 13:49:13.453312 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 11103, win 501, options [nop,nop,TS val 1818575221 ecr 2910345605,nop,nop,sack 1 {10676:11103}], length 0 13:49:13.618140 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818575386 ecr 2910345605], length 444 13:49:13.640349 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910346045 ecr 1818571754], length 427 13:49:13.836702 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 11103, win 501, options [nop,nop,TS val 1818575606 ecr 2910346045,nop,nop,sack 1 {10676:11103}], length 0 13:49:14.034097 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818575802 ecr 2910346045], length 444 13:49:14.520347 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910346925 ecr 1818571754], length 427 13:49:14.720278 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 11103, win 501, options [nop,nop,TS val 1818576489 ecr 2910346925,nop,nop,sack 1 {10676:11103}], length 0 13:49:14.865148 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818576634 ecr 2910346925], length 444 13:49:16.312366 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910348717 ecr 1818571754], length 427 13:49:16.533325 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818578302 ecr 2910346925], length 444 13:49:16.572702 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 11103, win 501, options [nop,nop,TS val 1818578341 ecr 2910348717,nop,nop,sack 1 {10676:11103}], length 0 13:49:19.832241 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910352237 ecr 1818571754], length 427 13:49:19.889067 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [P.], seq 11101:11545, ack 11103, win 501, options [nop,nop,TS val 1818581658 ecr 2910348717], length 444 13:49:20.045815 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [.], ack 11103, win 501, options [nop,nop,TS val 1818581813 ecr 2910352237,nop,nop,sack 1 {10676:11103}], length 0 13:49:27.128254 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910359533 ecr 1818571754], length 427 13:49:27.351103 wlp0s20f3 In IP 192.76.120.10.sip > 192.168.143.246.58732: Flags [R], seq 3545231578, win 0, length 0 13:49:41.464389 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910373869 ecr 1818571754], length 427 13:50:09.624232 wlp0s20f3 Out IP 192.168.143.246.58732 > 192.76.120.10.sip: Flags [P.], seq 10676:11103, ack 11101, win 501, options [nop,nop,TS val 2910402029 ecr 1818571754], length 427 ``` And according to network traffic kamailio keep failed tcp connections open durring 3o min.