// check RST packet that doesn't exactly match expected next sequence // number still transitions conntrack state to CLOSE iff its already in // FIN/CLOSE_WAIT. `packetdrill/common.sh` // 5.771921 server_ip > client_ip TLSv1.2 337 [Packet size limited during capture] // 5.771994 server_ip > client_ip TLSv1.2 337 [Packet size limited during capture] // 5.772212 client_ip > server_ip TCP 66 45020 > 443 [ACK] Seq=1905874048 Ack=781810658 Win=36352 Len=0 TSval=3317842872 TSecr=675936334 // 5.787924 server_ip > client_ip TLSv1.2 1300 [Packet size limited during capture] // 5.788126 server_ip > client_ip TLSv1.2 90 Application Data // 5.788207 server_ip > client_ip TCP 66 443 > 45020 [FIN, ACK] Seq=781811916 Ack=1905874048 Win=31104 Len=0 TSval=675936350 TSecr=3317842872 // 5.788447 client_ip > server_ip TLSv1.2 90 Application Data // 5.788479 client_ip > server_ip TCP 66 45020 > 443 [RST, ACK] Seq=1905874072 Ack=781811917 Win=39040 Len=0 TSval=3317842889 TSecr=675936350 // 5.788581 server_ip > client_ip TCP 54 8443 > 45020 [RST] Seq=781811892 Win=0 Len=0 +0 `iptables -A INPUT -p tcp -m conntrack --ctstate INVALID -j DROP` +0 `iptables -A OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 0.1 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress) 0.1 > S 0:0(0) win 65535 +0.1 < S. 1:1(0) ack 1 win 65535 +0 > . 1:1(0) ack 1 win 65535 +0 < . 1:1001(1000) ack 1 win 65535 +0 < . 1001:2001(1000) ack 1 win 65535 +0 < . 2001:3001(1000) ack 1 win 65535 +0 > . 1:1(0) ack 1001 win 65535 +0 > . 1:1(0) ack 2001 win 65535 +0 > . 1:1(0) ack 3001 win 65535 +0 write(3, ..., 1000) = 1000 +0.0 > P. 1:1001(1000) ack 3001 win 65535 +0.1 read(3, ..., 1000) = 1000 // Conntrack should move to FIN_WAIT, then CLOSE_WAIT. +0 < F. 3001:3001(0) ack 1001 win 65535 +0 > . 1001:1001(0) ack 3002 win 65535 +0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q CLOSE_WAIT` +1 close(3) = 0 // RST: unread data. FIN was seen, hence ack + 1 +0 > R. 1001:1001(0) ack 3002 win 65535 // ... and then, CLOSE. +0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q CLOSE\ ` // Spurious RST from peer -- no sk state. Should NOT get // marked INVALID, because conntrack is already closing. +0.1 < R 2001:2001(0) win 0 // No packets should have been marked INVALID +0 `iptables -v -S INPUT | grep INVALID | grep -q -- "-c 0 0"` +0 `iptables -v -S OUTPUT | grep INVALID | grep -q -- "-c 0 0"`