Network Statistics

"Netstat -s -P tcp" provides you with detail summary of the Tcp statistics. See below

$ netstat -s -P tcp

TCP     tcpRtoAlgorithm     =     4     tcpRtoMin           =   400
        tcpRtoMax           = 60000     tcpMaxConn          =    -1
        tcpActiveOpens      =   105     tcpPassiveOpens     =  6929
        tcpAttemptFails     =     9     tcpEstabResets      =    24
        tcpCurrEstab        =    10     tcpOutSegs          =14831657
        tcpOutDataSegs      =14504882   tcpOutDataBytes     =1579349845
        tcpRetransSegs      =   398     tcpRetransBytes     =116003
        tcpOutAck           =326541     tcpOutAckDelayed    =204020
        tcpOutUrg           =     0     tcpOutWinUpdate     =     0
        tcpOutWinProbe      =     0     tcpOutControl       = 14170
        tcpOutRsts          =    14     tcpOutFastRetrans   =    14
        tcpInSegs           =14736303
        tcpInAckSegs        =14290274   tcpInAckBytes       =1579351049
        tcpInDupAck         = 10033     tcpInAckUnsent      =     0
        tcpInInorderSegs    =14467627   tcpInInorderBytes   =681280146
        tcpInUnorderSegs    =    60     tcpInUnorderBytes   =  3120
        tcpInDupSegs        =    62     tcpInDupBytes       =  2184
        tcpInPartDupSegs    =     0     tcpInPartDupBytes   =     0
        tcpInPastWinSegs    =     0     tcpInPastWinBytes   =     0
        tcpInWinProbe       =     0     tcpInWinUpdate      =     0
        tcpInClosed         =     0     tcpRttNoUpdate      =   103
        tcpRttUpdate        =14283487   tcpTimRetrans       =   300
        tcpTimRetransDrop   =    12     tcpTimKeepalive     =  9353
        tcpTimKeepaliveProbe=  2967     tcpTimKeepaliveDrop =     0
        tcpListenDrop       =     0     tcpListenDropQ0     =     0
        tcpHalfOpenDrop     =     0     tcpOutSackRetrans   =    49

It is possible to timestamp each of these network metrics. If you collect them over a period of time, you can plot it with Gnuplot and study the trend of these TCP parameters.

This script should be able to do this job as a normal user and it will append timestamp and metrics to individual parameter files. So all you have to do is to loop through the script with a while loop. I will leave this to the reader as an exercise.

$ls
net.sh

$ cat net.sh
#! /bin/sh

timestamp=`date '+%Y%m%d%H%M%S'`


netstat -s -P tcp | \
sed -e 's/=/ /g' -e 's/TCP//' | \
nawk -v ts=$timestamp '
NF==2 {
        cmd=sprintf("echo %s %s >> %s",ts,$2,$1)
        system(cmd)
}
NF==4 {
        cmd=sprintf("echo %s %s >> %s",ts,$2,$1)
        system(cmd)
        cmd=sprintf("echo %s %s >> %s",ts,$4,$3)
        system(cmd)
}'

$ ls
net.sh                tcpInDupBytes         tcpInWinUpdate tcpOutSackRetrans     tcpRttNoUpdate
tcpActiveOpens        tcpInDupSegs          tcpListenDrop tcpOutSegs            tcpRttUpdate
tcpAttemptFails       tcpInInorderBytes     tcpListenDropQ0 tcpOutUrg             tcpTimKeepalive
tcpCurrEstab          tcpInInorderSegs      tcpMaxConn tcpOutWinProbe        tcpTimKeepaliveDrop
tcpEstabResets        tcpInPartDupBytes     tcpOutAck tcpOutWinUpdate       tcpTimKeepaliveProbe
tcpHalfOpenDrop       tcpInPartDupSegs      tcpOutAckDelayed tcpPassiveOpens       tcpTimRetrans
tcpInAckBytes         tcpInPastWinBytes     tcpOutControl tcpRetransBytes       tcpTimRetransDrop
tcpInAckSegs          tcpInPastWinSegs      tcpOutDataBytes tcpRetransSegs
tcpInAckUnsent        tcpInUnorderBytes     tcpOutDataSegs tcpRtoAlgorithm
tcpInClosed           tcpInUnorderSegs      tcpOutFastRetrans     tcpRtoMax
tcpInDupAck           tcpInWinProbe         tcpOutRsts            tcpRtoMin

$ more tcpActiveOpens
20070712081804 29