DTCB(1M) Domain/OS SysV DTCB(1M)
NAME
dtcb - dump contents of TCP control blocks
SYNOPSIS
/etc/dtcb [-f] [-m] [-p] [ -a | -d | -u [<ucb_addr>] | -t [<tcb_addr>] ]
DESCRIPTION
The command dtcb dumps the contents of the TCP control blocks associated
with a particular TCP connection. Two control blocks are dumped: the UCB
(user control block), which contains the send and receive queues and
user-related flags; and the TCB (TCP control block), which contains the
connection sequence numbers, state, flags, and out-of-sequence queues.
Obtain the address of the TCB to be dumped by using the netstat -A
command. The TCB is listed under the column headed with PCB. Obtain the
UCB for a socket by executing the dtcb command on the socket's TCB.
OPTIONS
-f Force output if tcpd not running.
-m Print both TCB and UCB for a single socket.
-p Print the PID, GID, and process name of the process that
created the socket.
-a Print both TCB and UCB for all sockets.
-d Print the UCB or TCB for all sockets that have SO_DEBUG
enabled -- for example, FTP data connections opened with
the ftp debug command or TELNET connections opened with
the telnet -d command.
-u <ucb_addr> Print the UCB specified by the hexadecimal address
<ucb_addr> or, if no address is specified, all UCBs.
-t <tcb_addr> Print the TCB specified by the hexadecimal address
<tcb_addr> or, if no address is specified, all TCBs.
EXAMPLES
The dump of a TCP control block for a listening FTP connection might look
like this:
$ /etc/dtcb -m -t e9064d4
############################################
---------- TCB at e9064d4 UCB at e90786c:
lport 0 fport 0
t_state ESTAB
irs 24A3A08B rcv_urp 24A3A08B rcv_urg 24A3A08C rcv_nxt 24A3A0A6
rcv_end 00000000
iss 251A4222 seq_fin 251A4222 snd_end 251A42B8 snd_urp 00000000
snd_lst 251A42B8
snd_nxt 251A42B8 snd_una 251A42B8 snd_wl 24A3A0A6 snd_hi 251A42B8
rex_val 251A42B8 rtl_val 251A42B8 xmt_val 251A429B
tcb flags:
SYN_ACKED SYN_RCVD
snd_wnd 9116 maxseg 1420 xmtime 3 rxtct 0
timers:
INIT 0 REXMT 0 REXMTTL 0 PERSIST 0 FINACK 0
t_rcv_next E9064D4 t_rcv_prev E9064D4
---------- UCB at e90786c TCB at e9064d4:
local 192.9.99.4.21 host 192.9.99.3.1026
uc_snd 9116 uc_ssize 0 uc_rcv 9116 uc_rsize 0
uc_shead 0 uc_stail 0 uc_rhead 0 uc_rtail 0
uc_srcif itr0 uc_refcnt 0
uc_qhead 0 uc_gway 0
uc_q0 0
uc_q 0
uc_xflag (0001): ULINKED
uc_iostate (2000): IS_CONNECTED
uc_status (0000):
uc_flags (0002): UTCP
uc_options (0104): SO_REUSEADDR SO_OOBINLINE
uc_error 0 uc_xstat 0 uc_backlog 0
oobmark 0 oobcnt 0
SEE ALSO
Configuring and Managing TCP/IP.