Network tool to test network bandwidth and performance
install netperf by souce code on both server and client.
server side:
start netperf
#netserver
client side:
netperf -H remote.lalife.net
Category Archives: Linux
screen
To open a new screen
#screen
To detach it
#screen -d
To get list of screens
#screen -list
13827.pts-4.servername
To resume it
#screen -r 13827
To sudo to a different user aaa then use screen
sudo -u aaa -s
script /dev/null
screen
Ref. http://dbadump.blogspot.com/2009/04/start-screen-after-sudo-su-to-another.html
screen
start screen
#screen
detach
#screen -d
resume
#screen -r (single)
or
#screen -x (multi)
telnet smtpserver 25
HELO smtp.lalife.net
MAIL FROM: test@localhost
RCPT TO: test@lalife.net
DATA
FROM:test@localhost
Subject: test smtp
test smtp.
.
QUIT
Another way to send mail by command line
echo “testmail” | mail -s “test” yan@yan.lalife.net
iptraf
iptraf is a tool used to monitor the network traffic
To add more ports (beyond 104)
iptraf > Enter > Configure > Additional Ports
To change log interval
iptraf > Enter > Timers > Logging interval
Add/Delete/Active/Unactive Filter
iptraf > Enter > IP
Monitor traffic statistics by port
iptraf > Enter > Statistical breakdowns…
To run iptraf background for 10 min and send data to log files
/usr/bin/iptraf -B -s eth0 -t 10
Log file is under /var/log/iptraf/ by default
vnstat — monitoring network traffic
Install vnstat
tar -zxvf vnstat-1.xx.tar.gz
Compile and install
make all
make install
Use vnstat
create new database
vnstat -u -i eth0
database is created under /var/lib/vnstat/eth0
Setup cron to collect data
copy from examples/vnstat.cron
#vnstat
#vnstat -i eth0
#vnstat -d
#vnstat -m
rx = recieved
tx = transmitted
Access https by telnet
openssl s_client -connect mysite.com:443
To retrieve a certificate
openssl s_client -connect sdms.ecp:443 2>&1 | sed -ne ‘/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p’
Useful page:
http://www.madboa.com/geek/openssl/
mysqldump
1. dump all database into backup file
mysqldump –opt –all-databases > /tmp/databkup
(–opt includes lock table option)
2. dump several databases
mysqldump –opt –databases db1 db2 db3 > /tmp/databkup
3. dump single table
mysqldump –opt db1 table1 > /tmp/databkup
Touble shooting
Error: Access denied for user x@y to database z when using lock tables
mysqldump -u username -p database –single-transaction >dump.sql
User tar to back up db
mysql> FLUSH TABLES WITH READ LOCK;
(This will lock the db so it won’t be updated by other threads. Write threads by other process will wait till the lock is released)
#tar cvzf /var/tmp/datadump.tgz /var/lib/mysql/*
mysql> UNLOCK TABLES;
Restore data
lock tables bbb write;
mysql bbb < /data_backup/databkup
unlock tables;
SSH key setup in cluster servers
Setup keys for xxx to login yyy without password
[xxx-sync@xxx ~]$ ssh-keygen -t dsa
cp id_dsa.pub to xxx /home/xxx-sync/.ssh
requiretty
Some cron didn’t work well after move to CentOS5
New to disable requiretty
May 19 10:40:01 xxx sudo: root : sorry, you must have a tty to run sudo ; TTY=unknown ; PWD=/www/xxx/bin ; USER=xxx ; COMMAND=/bin/sh moviepagechmod.sh
vi /etc/sudoers
#Defaults requiretty