+Show internal TCP information. Below fields may appear:
+.RS
+.P
+.TP
+.B ts
+show string "ts" if the timestamp option is set
+.P
+.TP
+.B sack
+show string "sack" if the sack option is set
+.P
+.TP
+.B ecn
+show string "ecn" if the explicit congestion notification option is set
+.P
+.TP
+.B ecnseen
+show string "ecnseen" if the saw ecn flag is found in received packets
+.P
+.TP
+.B fastopen
+show string "fastopen" if the fastopen option is set
+.P
+.TP
+.B cong_alg
+the congestion algorithm name, the default congestion algorithm is "cubic"
+.P
+.TP
+.B wscale:<snd_wscale>:<rcv_wscale>
+if window scale option is used, this field shows the send scale factor
+and receive scale factor
+.P
+.TP
+.B rto:<icsk_rto>
+tcp re-transmission timeout value, the unit is millisecond
+.P
+.TP
+.B backoff:<icsk_backoff>
+used for exponential backoff re-transmission, the actual
+re-transmission timeout value is icsk_rto << icsk_backoff
+.P
+.TP
+.B rtt:<rtt>/<rttvar>
+rtt is the average round trip time, rttvar is the mean deviation of
+rtt, their units are millisecond
+.P
+.TP
+.B ato:<ato>
+ack timeout, unit is millisecond, used for delay ack mode
+.P
+.TP
+.B mss:<mss>
+max segment size
+.P
+.TP
+.B cwnd:<cwnd>
+congestion window size
+.P
+.TP
+.B pmtu:<pmtu>
+path MTU value
+.P
+.TP
+.B ssthresh:<ssthresh>
+tcp congestion window slow start threshold
+.P
+.TP
+.B bytes_acked:<bytes_acked>
+bytes acked
+.P
+.TP
+.B bytes_received:<bytes_received>
+bytes received
+.P
+.TP
+.B segs_out:<segs_out>
+segments sent out
+.P
+.TP
+.B segs_in:<segs_in>
+segments received
+.P
+.TP
+.B send <send_bps>bps
+egress bps
+.P
+.TP
+.B lastsnd:<lastsnd>
+how long time since the last packet sent, the unit is millisecond
+.P
+.TP
+.B lastrcv:<lastrcv>
+how long time since the last packet received, the unit is millisecond
+.P
+.TP
+.B lastack:<lastack>
+how long time since the last ack received, the unit is millisecond
+.P
+.TP
+.B pacing_rate <pacing_rate>bps/<max_pacing_rate>bps
+the pacing rate and max pacing rate
+.P
+.TP
+.B rcv_space:<rcv_space>
+a helper variable for TCP internal auto tuning socket receive buffer
+.RE
+.TP
+.B \-\-tos
+Show ToS and priority information. Below fields may appear:
+.RS
+.P
+.TP
+.B tos
+IPv4 Type-of-Service byte
+.P
+.TP
+.B tclass
+IPv6 Traffic Class byte
+.P
+.TP
+.B class_id
+Class id set by net_cls cgroup. If class is zero this shows priority
+set by SO_PRIORITY.
+.RE
+.TP
+.B \-K, \-\-kill
+Attempts to forcibly close sockets. This option displays sockets that are
+successfully closed and silently skips sockets that the kernel does not support
+closing. It supports IPv4 and IPv6 sockets only.