Receiver mtu 1420, sender mtu 1412, successful transfer: # tcpdump -i wg0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on wg0, link-type RAW (Raw IP), capture size 262144 bytes 15:42:35.027995 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [S], seq 4148302601, win 27040, options [mss 1352,sackOK,TS val 2239613851 ecr 0,nop,wscale 9], length 0 15:42:35.028026 IP6 fd39:30::250.5001 > fd39:30::2.42414: Flags [S.], seq 505975510, ack 4148302602, win 26960, options [mss 1360,sackOK,TS val 1473426057 ecr 2239613851,nop,wscale 9], length 0 15:42:35.102517 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [.], ack 1, win 53, options [nop,nop,TS val 2239613925 ecr 1473426057], length 0 15:42:35.102772 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [.], seq 1:1341, ack 1, win 53, options [nop,nop,TS val 2239613925 ecr 1473426057], length 1340 15:42:35.102785 IP6 fd39:30::250.5001 > fd39:30::2.42414: Flags [.], ack 1341, win 58, options [nop,nop,TS val 1473426131 ecr 2239613925], length 0 15:42:35.102810 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [P.], seq 1341:2145, ack 1, win 53, options [nop,nop,TS val 2239613925 ecr 1473426057], length 804 15:42:35.102818 IP6 fd39:30::250.5001 > fd39:30::2.42414: Flags [.], ack 2145, win 64, options [nop,nop,TS val 1473426131 ecr 2239613925], length 0 15:42:35.729846 IP6 fd39:30::250.5001 > fd39:30::2.42162: Flags [F.], seq 1811803733, ack 3749581328, win 56, options [nop,nop,TS val 1473426758 ecr 2239251660,nop,nop,sack 1 {1341:2145}], length 0 15:42:35.804023 IP6 fd39:30::2.42162 > fd39:30::250.5001: Flags [.], ack 1, win 54, options [nop,nop,TS val 2239614627 ecr 1473426758,nop,nop,sack 1 {0:1}], length 0 15:42:36.939584 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [F.], seq 2145, ack 1, win 53, options [nop,nop,TS val 2239615763 ecr 1473426131], length 0 15:42:36.939723 IP6 fd39:30::250.5001 > fd39:30::2.42414: Flags [F.], seq 1, ack 2146, win 64, options [nop,nop,TS val 1473427968 ecr 2239615763], length 0 15:42:37.014143 IP6 fd39:30::2.42414 > fd39:30::250.5001: Flags [.], ack 2, win 53, options [nop,nop,TS val 2239615837 ecr 1473427968], length 0 ^C 12 packets captured 12 packets received by filter 0 packets dropped by kernel ======================================================= Receiver mtu 1408, sender mtu 1420, successful transfer: # tcpdump -i wg0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on wg0, link-type RAW (Raw IP), capture size 262144 bytes 15:43:23.935508 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [S], seq 1011924297, win 27200, options [mss 1360,sackOK,TS val 2239662759 ecr 0,nop,wscale 9], length 0 15:43:23.935541 IP6 fd39:30::250.5001 > fd39:30::2.42442: Flags [S.], seq 1735470303, ack 1011924298, win 26720, options [mss 1348,sackOK,TS val 1473474964 ecr 2239662759,nop,wscale 9], length 0 15:43:24.009867 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [.], ack 1, win 54, options [nop,nop,TS val 2239662834 ecr 1473474964], length 0 15:43:24.010192 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [.], seq 1:1337, ack 1, win 54, options [nop,nop,TS val 2239662834 ecr 1473474964], length 1336 15:43:24.010203 IP6 fd39:30::250.5001 > fd39:30::2.42442: Flags [.], ack 1337, win 58, options [nop,nop,TS val 1473475039 ecr 2239662834], length 0 15:43:24.010206 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [P.], seq 1337:2145, ack 1, win 54, options [nop,nop,TS val 2239662834 ecr 1473474964], length 808 15:43:24.010213 IP6 fd39:30::250.5001 > fd39:30::2.42442: Flags [.], ack 2145, win 63, options [nop,nop,TS val 1473475039 ecr 2239662834], length 0 15:43:26.669491 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [F.], seq 2145, ack 1, win 54, options [nop,nop,TS val 2239665493 ecr 1473475039], length 0 15:43:26.669531 IP6 fd39:30::250.5001 > fd39:30::2.42442: Flags [F.], seq 1, ack 2146, win 63, options [nop,nop,TS val 1473477698 ecr 2239665493], length 0 15:43:26.744246 IP6 fd39:30::2.42442 > fd39:30::250.5001: Flags [.], ack 2, win 54, options [nop,nop,TS val 2239665568 ecr 1473477698], length 0 ^C 10 packets captured 10 packets received by filter 0 packets dropped by kernel ======================================================= Receiver mtu 1412, sender mtu 1420, locked-up transfer: # tcpdump -i wg0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on wg0, link-type RAW (Raw IP), capture size 262144 bytes 15:44:47.350436 IP6 fd39:30::2.42536 > fd39:30::250.5001: Flags [S], seq 1322713189, win 27200, options [mss 1360,sackOK,TS val 2239746176 ecr 0,nop,wscale 9], length 0 15:44:47.350510 IP6 fd39:30::250.5001 > fd39:30::2.42536: Flags [S.], seq 167242985, ack 1322713190, win 26800, options [mss 1352,sackOK,TS val 1473558379 ecr 2239746176,nop,wscale 9], length 0 15:44:47.424806 IP6 fd39:30::2.42536 > fd39:30::250.5001: Flags [.], ack 1, win 54, options [nop,nop,TS val 2239746250 ecr 1473558379], length 0 15:44:47.425210 IP6 fd39:30::2.42536 > fd39:30::250.5001: Flags [P.], seq 1341:2145, ack 1, win 54, options [nop,nop,TS val 2239746250 ecr 1473558379], length 804 15:44:47.425231 IP6 fd39:30::250.5001 > fd39:30::2.42536: Flags [.], ack 1, win 56, options [nop,nop,TS val 1473558454 ecr 2239746250,nop,nop,sack 1 {1341:2145}], length 0 15:44:51.199602 IP6 fd39:30::2.42536 > fd39:30::250.5001: Flags [F.], seq 2145, ack 1, win 54, options [nop,nop,TS val 2239750025 ecr 1473558454], length 0 15:44:51.199627 IP6 fd39:30::250.5001 > fd39:30::2.42536: Flags [.], ack 1, win 56, options [nop,nop,TS val 1473562228 ecr 2239746250,nop,nop,sack 1 {1341:2146}], length 0 ^C 7 packets captured 7 packets received by filter 0 packets dropped by kernel