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#!/bin/bash # squid This shell script takes care of starting and stopping # Squid Internet Object Cache # # chkconfig: - 90 25 # description: Squid - Internet Object Cache. Internet object caching is \ # a way to store requested Internet objects (i.e., data available \ # via the HTTP, FTP, and gopher protocols) on a system closer to the \ # requesting site than to the source. Web browsers can then use the \ # local Squid cache as a proxy HTTP server, reducing access time as \ # well as bandwidth consumption. # pidfile: /var/run/squid.pid # config: /etc/squid/squid.conf PATH=/usr/bin:/sbin:/bin:/usr/sbin export PATH # Source function library. . /etc/rc.d/init.d/functions # Source networking configuration. . /etc/sysconfig/network # Check that networking is up. [ ${NETWORKING} = "no" ] && exit 0 # check if the squid conf file is present [ -f /usr/local/squid/etc/squid.conf ] || exit 0 # determine the name of the squid binary [ -f /usr/local/squid/sbin/squid ] && SQUID=squid [ -z "$SQUID" ] && exit 0 prog="$SQUID" # determine which one is the cache_swap directory CACHE_SWAP=`sed -e 's/#.*//g' /usr/local/squid/etc/squid.conf | \ grep cache_dir | awk '{ print $3 }'` [ -z "$CACHE_SWAP" ] && CACHE_SWAP=/usr/local/squid/var/cache RETVAL=0 start() { for adir in $CACHE_SWAP; do if [ ! -d $adir/00 ]; then echo -n "init_cache_dir $adir... " /usr/local/squid/sbin/squid -z -F 2>/dev/null fi done echo -n $"Starting $SQUID $prog: " /usr/local/squid/sbin/squid $SQUID_OPTS 2> /dev/null & RETVAL=$? [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$SQUID [ $RETVAL -eq 0 ] && echo_success [ $RETVAL -ne 0 ] && echo_failure echo return $RETVAL } stop() { echo -n $"Stopping $prog: " /usr/local/squid/sbin/squid -k check >/dev/null 2>&1 RETVAL=$? if [ $RETVAL -eq 0 ] ; then /usr/local/squid/sbin/squid -k shutdown & rm -f /var/lock/subsys/$SQUID timeout=0 while : ; do [ -f /usr/local/squid/var/logs/squid.pid ] || break sleep 2 && echo -n "." timeout=$((timeout+2)) done echo_success echo else echo_failure echo fi return $RETVAL } reload() { /usr/local/squid/sbin/squid $SQUID_OPTS -k reconfigure } restart() { stop start } condrestart() { [ -e /var/lock/subsys/squid ] && restart || : } rhstatus() { status $SQUID /usr/local/squid/sbin/squid -k check } probe() { return 0 } case "$1" in start) start ;; stop) stop ;; reload) reload ;; restart) restart ;; condrestart) condrestart ;; status) rhstatus ;; probe) exit 0 ;; *) echo $"Usage: $0 {start|stop|status|reload|restart|condrestart}" exit 1 esac exit $? |
Route Table Testing
Use this command:
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> ip route get <i>{dest ip}</i> |
To test from a specific source use:
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> ip route get <i>{dest ip}</i> from <i>{src ip}</i> |
Advanced Networking Resources
http://linux-ip.net – Great online book about advanced networking issues.
http://lartc.org/ – Howto and man pages
Performance Monitoring
Here are some handy commands that I used recently to debug a server performance issue:
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<strong>> sar</strong> Linux 2.4.9-34smp (some.server.net) 07/28/2004 12:00:00 AM CPU %user %nice %system %idle 12:10:00 AM all 12.29 2.00 4.55 81.16 12:20:00 AM all 4.14 0.16 2.58 93.13 12:30:00 AM all 4.46 0.02 2.79 92.74 12:40:01 AM all 3.68 0.04 2.36 93.92 12:50:00 AM all 3.78 0.03 2.47 93.72 01:00:00 AM all 3.89 0.10 2.42 93.59 01:10:00 AM all 6.65 0.62 2.70 90.03 01:20:00 AM all 5.56 0.31 2.85 91.27 01:30:00 AM all 4.04 0.02 2.40 93.53 01:40:00 AM all 4.41 0.58 2.92 92.09 01:50:01 AM all 5.63 0.73 3.13 90.51 02:00:00 AM all 3.58 0.03 2.19 94.19 02:10:00 AM all 8.19 0.03 2.39 89.39 02:20:00 AM all 4.84 0.00 2.90 92.25 02:30:00 AM all 6.77 0.59 2.86 89.78 02:40:01 AM all 4.04 0.02 2.99 92.94 02:50:00 AM all 4.60 0.03 2.83 92.55 03:00:00 AM all 5.67 0.29 2.83 91.21 03:10:00 AM all 4.58 0.13 2.99 92.29 03:20:00 AM all 8.69 0.80 3.46 87.05 03:30:01 AM all 5.32 0.22 3.10 91.36 03:40:01 AM all 4.85 0.06 3.23 91.85 03:50:00 AM all 3.73 0.00 2.72 93.55 04:00:00 AM all 3.40 0.02 2.27 94.31 04:10:00 AM all 40.16 0.09 8.79 50.96 04:20:00 AM all 44.44 0.04 10.07 45.45 04:30:00 AM all 32.32 1.06 10.09 56.53 04:40:00 AM all 38.10 0.04 7.05 54.81 04:50:01 AM all 32.80 0.02 8.07 59.12 05:00:02 AM all 32.89 2.06 13.31 51.74 05:10:00 AM all 42.18 0.49 9.52 47.81 05:20:01 AM all 53.17 2.62 9.76 34.44 05:30:00 AM all 18.56 6.41 16.87 58.15 05:40:00 AM all 38.36 0.04 9.80 51.80 05:50:00 AM all 26.03 0.24 9.35 64.38 06:00:00 AM all 30.65 0.97 9.82 58.56 06:10:01 AM all 44.41 0.07 9.51 46.00 06:20:00 AM all 25.11 0.14 12.42 62.34 06:30:00 AM all 37.65 0.02 12.12 50.21 Average: all 17.02 0.54 5.76 76.68 |
Also “sar -A” give more useful info.
For sar to work, you need a cronjob like this:
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# run system activity accounting tool every 10 minutes */10 * * * * root /usr/lib/sa/sa1 1 1 |
The cronjob can go in a file at /etc/cron.d/sysstat on Redhat and similar systems.
Another useful command is “vmstat”:
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<strong>> vmstat 1</strong> procs memory swap io system cpu r b w swpd free buff cache si so bi bo in cs us sy id 0 5 0 44856 3040 50504 273364 1 2 78 107 53 129 20 6 74 1 5 0 44856 3164 50552 274176 0 0 2288 1036 513 766 21 11 68 1 4 0 44856 3056 50556 273496 0 0 3128 116 443 507 7 6 87 2 3 0 44856 3236 50564 274800 0 0 3200 460 557 558 8 7 85 |
Preferences vs. Command Line Options
Here’s my question answered by the author of DSpam – Jonathan Zdziarski:
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> When calling dpsam, what takes precedence - user preferences or command line > options? User preferences; if you don't want your users to be able to override certain ones, you'll need to remove them from the prefs page. |