tyt07fi.htm

一个学习tcp/ip协议的教程

<FONT COLOR=#000080>$ netstat -m

streams allocation:

                     config   alloc    free   total     max    fail

streams                 292      79     213     233      80       0

queues                 1424     362    1062     516     368       0

mblks                  5067     196    4871    3957     206       0

dblks                  4054     196    3858    3957     206       0

class 0,    4 bytes     652      50     602     489      53       0

class 1,   16 bytes     652       2     650     408       4       0

class 2,   64 bytes     768       6     762    2720      14       0

class 3,  128 bytes     872     105     767     226     107       0

class 4,  256 bytes     548      21     527      36      22       0

class 5,  512 bytes     324      12     312      32      13       0

class 6, 1024 bytes     107       0     107       1       1       0

class 7, 2048 bytes      90       0      90       7       1       0

class 8, 4096 bytes      41       0      41      38       1       0

total configured streams memory: 1166.73KB

streams memory in use: 44.78KB

maximum streams memory used: 58.57KB</FONT></PRE><P>For the administrator, the failure column is important. It should always show 0s. If a larger number appears, that resource has been overtaxed and the number of blocks assigned to that resource should be increased (followed by a kernel rebuild and a reboot of the system to effect the changes).<BR><BR><A ID=E69E107 NAME=E69E107></A><H4 ALIGN=CENTER><CENTER><FONT SIZE=4 COLOR=#FF0000><B>Routing Table Information</B></FONT></CENTER></H4><BR><P>Routing tables are continually updated to reflect connections to other machines. To obtain information about the routing tables, the netstat -r and -rs options are used. (The latter generates statistics about the routing tables.)<BR><P>The output from netstat -r and netstat -rs commands are shown in the following code example. The columns show the destination machine, the address of the gateway to be used, a flag to show whether the route is active (U) and whether it leads to a gateway or a machine (H for host), a reference counter (Refs) that specifies how many active connections can use that route simultaneously, the number of packets that have been sent over the route (Use), and the interface name.<BR><PRE>

<FONT COLOR=#000080>$ netstat -r

Routing tables

Destination      Gateway            Flags    Refs     Use  Interface

localhost        localhost          UH          4      10  lo0

merlin           localhost          UH          2       2  ec0

treijs           hoytgate           UG          0       0  ec0

47.80            bcarh736           U          12   21029  lan0

tpci sco4-57&gt; netstat -rs

routing:

              0 bad routing redirects

              0 dynamically created routes

              0 new gateways found unreachable

              2 destinations found unreachable

            122 uses of a wildcard route

              0 routes marked doutbful

              0 routes cleared of being doubtful

              0 routes deleted</FONT></PRE><BR><A ID=E69E108 NAME=E69E108></A><H4 ALIGN=CENTER><CENTER><FONT SIZE=4 COLOR=#FF0000><B>Protocol Statistics</B></FONT></CENTER></H4><BR><P>Statistics about the overall behavior of network protocols can be obtained with the netstat -s command. This usually provides summaries for IP, ICMP, TCP, and UDP. The output from this command is useful for determining where an error in a received packet was located, which then leads the user to isolate whether that error was caused by a software or network problem.<BR><P>Issuing the netstat -s command provides a verbose output. A sample output is shown in the following code. The entries are self-explanatory.<BR><PRE>

<FONT COLOR=#000080>tpci_sco4-67&gt; netstat -s

ip:

     183309 total packets received

     0 bad header checksums

     0 with size smaller than minimum

     0 with data size &lt; data length

     0 with header length &lt; data size

     0 with data length &lt; header length

     0 with unknown protocol

     13477 fragments received

     0 fragments dropped (dup or out of space)

     0 fragments dropped after timeout

     0 packets reassembled

     0 packets forwarded

     0 packets not forwardable

     75 no routes

     0 redirects sent

     0 system errors during input

     309 packets delivered

     309 total packets sent

     0 system errors during output

     0 packets fragmented

     0 packets not fragmentable

     0 fragments created

icmp:

     1768 calls to icmp_error

     0 errors not generated because old message was icmp

     Output histogram:

          destination unreachable: 136

     0 messages with bad code fields

     0 messages &lt; minimum length

     0 bad checksums

     0 messages with bad length

     Input histogram:

          destination unreachable: 68

     0 message responses generated

     68 messages received

     68 messages sent

     0 system errors during output

tcp:

    9019 packets sent

              6464 data packets (1137192 bytes)

          4 data packets (4218 bytes) retransmitted