Resolved – input_userauth_request: invalid user root

May 15th, 2014

Today when I tried to ssh to one linux box but it failed, and /var/log/secure gave the following messages:

May 15 04:05:07 testbox sshd[22925]: User root from not allowed because not listed in AllowUsers
May 15 04:05:07 testbox sshd[22928]: input_userauth_request: invalid user root
May 15 04:05:07 testbox unix_chkpwd[22929]: password check failed for user (root)
May 15 04:05:07 testbox sshd[22925]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= user=root
May 15 04:05:09 testbox sshd[22925]: Failed password for invalid user root from port 50362 ssh2
May 15 04:05:10 testbox unix_chkpwd[22930]: password check failed for user (root)
May 15 04:05:11 testbox sshd[22928]: Connection closed by

Then I had a check of /etc/ssh/sshd_config and modified the following:

[root@testbox ~]# egrep 'PermitRoot|AllowUser' /etc/ssh/sshd_config
PermitRootLogin yes #change this to yes
#AllowUsers testuser #comment out this

Later, restart sshd, service sshd restart, and later ssh worked.

Categories: IT Architecture, Linux, Systems Tags: ,

resolved – fsinfo ERROR: Stale NFS file handle POST

May 15th, 2014

Today when I tried mount NFS share from one NFS server, it timeout with "mount.nfs: Connection timed out".

I tried to search something in /var/log/messages but no useful info there was found. So I used tcpdump on NFS client:

[root@dcs-hm1-qa132 ~]# tcpdump -nn -vvv host #server is, client is
23:49:11.598407 IP (tos 0x0, ttl 64, id 26179, offset 0, flags [DF], proto TCP (6), length 96) > 40 null
23:49:11.598741 IP (tos 0x0, ttl 62, id 61186, offset 0, flags [DF], proto TCP (6), length 80) > reply ok 24 null
23:49:11.598812 IP (tos 0x0, ttl 64, id 26180, offset 0, flags [DF], proto TCP (6), length 148) > 92 fsinfo fh Unknown/0100010000000000000000000000000000000000000000000000000000000000
23:49:11.599176 IP (tos 0x0, ttl 62, id 61187, offset 0, flags [DF], proto TCP (6), length 88) > reply ok 32 fsinfo ERROR: Stale NFS file handle POST:
23:49:11.599254 IP (tos 0x0, ttl 64, id 26181, offset 0, flags [DF], proto TCP (6), length 148) > 92 fsinfo fh Unknown/010001000000000000002FFF000002580000012C0007B0C00000000A00000000
23:49:11.599627 IP (tos 0x0, ttl 62, id 61188, offset 0, flags [DF], proto TCP (6), length 88) > reply ok 32 fsinfo ERROR: Stale NFS file handle POST:

The reason of "ERROR: Stale NFS file handle POST" may caused by the following reasons:

1.The NFS server is no longer available
2.Something in the network is blocking
3.In a cluster during failover of NFS resource the major & minor numbers on the secondary server taking over is different from that of the primary.

To resolve the issue, you can try bounce NFS service on NFS server using /etc/init.d/nfs restart.

Categories: Hardware, NAS, Storage Tags:

resolved – show kitchen sink buttons when wordpress goes to fullscreen mode

April 11th, 2014

When you click the full-screen button of wordpress TinyMCE, wordpress will go to "Distraction-Free Writing mode", which benefits as the name suggests. However, you'll also find the toolbox of TinyMCE will only show a limited number of buttons and the second line of the toolbox(kitchen sink) will not show at all(I tried install plugin such as ultimate TinyMCE or advanced TinyMCE, but the issue remained):

full-screenPreviously, you can type ALT+SHIFT+G to go to another type of fullscreen mode, which has all buttons include kitchen sink ones. However, seems now the updated version of wordpress has disabled this feature.

To resolve this issue, we can insert the following code in functions.php of your theme:

function my_mce_fullscreen($buttons) {
$buttons[] = 'fullscreen';
return $buttons;
add_filter('mce_buttons', 'my_mce_fullscreen');

Later, the TinyMCE will have two full-screen button:

full-screen buttonsMake sure to click the SECOND full-screen button. When you do so, the editor will transform to the following appearance:

full-screen with kitchen sinkI assume this is what you're trying for, right?



Categories: Misc Tags:

add horizontal line button in wordpress

April 11th, 2014

There're three methods for you to add a horizontal line button in wordpress:

Firstly, switch to "Text" mode, and enters <hr />.

Secondly, add the following in functions.php of your wordpress theme:

function enable_more_buttons($buttons) {
$buttons[] = 'hr';
return $buttons;
add_filter("mce_buttons", "enable_more_buttons");

horizontal line

Thirdly, you can install plugin "Ultimate TinyMCE", and in its setting, you can enable horizontal line button there in one click! This is my recommendation.

ultimate tinymce

Categories: Misc Tags: ,

linux tips

April 10th, 2014
Linux Performance & Troubleshooting


For Linux Performance & Troubeshooting, please refer to another post - Linux tips - Performance and Troubleshooting


Linux system tips


ls -lu(access time, like cat file) -lt(modification time, like vi, ls -l defaults to use this) -lc(change time, chmod), stat ./aa.txt <UTC>
ctrl +z #bg and stopped
%1 & #bg and running
%1 #fg
pgrep -flu oracle  # processes owned by the user oracle
watch free -m #refresh every 2 seconds
pmap -x 30420 #memory mapping.
openssl s_client -connect localhost:636 -showcerts #verify ssl certificates, or 443
openssl x509 -in cacert.pem -noout -text
openssl x509 -in cacert.pem -noout -dates
openssl x509 -in cacert.pem -noout -purpose
openssl req -in robots.req.pem -text -verify -noout
blockdev --getbsz /dev/xvda1 #get blocksize of FS
dumpe2fs /dev/xvda1 |grep 'Block size'
sed -i.bak2014 's/HISTSIZE=1000/HISTSIZE=100000/' /etc/profile
echo 71_testhost_emgc | sed -re 's/.*_(slce.*)_.*/\1/g' #output testhost
sed -re 's/User_Alias USERS_SDITAS.*/&, xiaozliu/g' a.txt #'&' refers to matched content
echo 'export HISTTIMEFORMAT=%h/%d - %H:%M:%S' >> /etc/profile




ovm svr ls|sort -rn -k 4 #sort by column 4
cat a1|sort|uniq -c |sort #SUS
ovm svr ls|uniq -f3 #skip the first three columns, this will list only 1 server per pool
for i in <all OVMs>;do ( $i &);done #instead of using nohup &
ovm vm ls|egrep "`echo testhost{0\|,1\|,2\|,3\|,4}|tr -d '[:space:]'`"
cat a|awk '{print $5}'|tr '\n' ' '
getopt #getopts is builtin
date -d '1970-1-1 1276059000 sec utc'
date -d '2010-09-11 23:20' +%s
find . -name '*txt'|xargs tar cvvf a.tar
find . -maxdepth 1
for i in `find /usr/sbin/ -type f ! -perm -u+x`;do chmod +x $i;done #files that has no execute permisson for owner
find ./* -prune -print #-prune,do not cascade
find . -fprint file #put result to file
tar tvf a.tar  --wildcards "*ipp*" #globbing patterns
tar xvf bfiles.tar --wildcards --no-anchored 'b*'
tar --show-defaults
tar cvf a.tar --totals *.txt #show speed
tar --append --file=collection.tar rock #add rock to collection.tar
tar --update -v -f collection.tar blues folk rock classical #only append new or updated ones, not replace
tar --delete --file=collection.tar blues #not on tapes
tar -c -f archive.tar --mode='a+rw'
tar -C sourcedir -cf - . | tar -C targetdir -xf - #copy directories
tar -c -f jams.tar grape prune -C food cherry #-C,change dir, foot file cherry under foot directory
find . -size -400 -print > small-files
tar -c -v -z -T small-files -f little.tgz
tar -cf src.tar --exclude='*.o' src #multiple --exclude can be specified
expr 5 - 1
rpm2cpio ./ash-1.0.1-1.x86_64.rpm |cpio -ivd
eval $cmd
exec menu.viewcards #same to .
ls . | xargs -0 -i cp ./{} /etc #-i,use \n as separator, just like find -exec. -0 for space in filename. find -print0 use space to separate, not enter.(-i or -I {} for revoking filenames in the middle)
ls | xargs -t -i mv {} {}.old #mv source should exclude /,or unexpected errors may occur
mv --strip-trailing-slashes source destination
ls |xargs file /dev/fd/0 #replace -
ls -l -I "*out*" #not include out
find . -type d |xargs -i du -sh {} |awk '$1 ~ /G/'
ovm svr ls|awk '$NF ~ /QA_GA_DC2$/'
ypcat passwd|awk -F: '{if($1 ~ /^user1$|^user2$/) print}'|grep false
for i in `ls -I shared -I oracle`;do du -sh $i;done #exclude shared and oracle directories
find . -type f -name "*20120606" -exec rm {} \; #do not need rm -rf. find . -type f -exec bash -c "ls -l '{}'" \;
ps -ef|grep init|sed -n '1p'
cut -d ' ' -f1,3 /etc/mtab #first and third
seq 15 21 #print 15 to 21, or echo {15..21}
seq -s" " 15 21 #use space as separator


Categories: IT Architecture, Linux, Systems Tags:

perl tips

April 2nd, 2014
use strict;
use warnings;##arrays
my @animals = ("dog", "pig", "cat");
print "The last element of array \$animals is : ".$animals[$#animals]."\n";
print "more than 2 animals found\n";
print "less than 2 animals found\n"
print $_."\n";
my %fruit_color=("apple", "red", "banana", "yellow");
print "Color of banana is : ".$fruit_color{"banana"}."\n";

for $char (keys %fruit_color)
print("$char => $fruit_color{$char}\n");

my $variables = {
scalar  =>  {
description => "single item",
sigil => '$',
array   =>  {
description => "ordered list of items",
sigil => '@',
hash    =>  {
description => "key/value pairs",
sigil => '%',
print "Scalars begin with a $variables->{'scalar'}->{'sigil'}\n";

##Files and I/O
##regular expressions
open (my $passwd, "<", "/etc/passwd2") or die ("can  a not open");
while (<$passwd>) {
print $_ if $_ =~ "test";
close $passwd or die "$passwd: $!";
my $next = "doing a first";
$next =~ s/first/second/;
print $next."\n";

my $email = "testaccount\";
if ($email =~ /([^@]+)@(.+)/) {
print "Username is : $1\n";
print "Hostname is : $2\n";

sub multiply{
my ($num1, $num2) = @_;
my $result = $num1 * $num2;
return $result;

my $result2 = multiply(3, 5);
print "3 * 5 = $result2\n";

! system('date') or die("failed it"); #if a subroutine returns ok, it'll return 0
Categories: IT Architecture, Perl, Programming Tags: