Insight Guide Troubleshoot Slow SSH Logins

Centmin Mod on initial login has a few checks it does for the following

• yum update checks
• nginx version checks

If you have slow SSH logins, it could be related to one of these checks. So to troubleshoot you can post a new thread in System Admin forums with info asked below:

1. Who's the web host ?
2. Which plan ?
3. location of VPS ?
4. Was it fast when you did initial install or was it always slow ?

what is output for these commands

Code (Text):

yum clean all
time yum repolist all

Code (Text):

time yum -v -d 9 list updates

Code (Text):

time yum -v -d 9 list updates --disableplugin=fastestmirror

Code (Text):

cat /root/centminlogs/yum-timedhosts.txt

Code (Text):

sort -k2 /var/cache/yum/x86_64/7/timedhosts.txt

Code (Text):

cat /etc/resolv.conf

Code (Text):

tail -1 $(ls -rt /root/centminlogs/cmm-login-git-checks* | tail -1)

Code (Text):

find /root/centminlogs/ -type f -name "cmm-login-git-checks_*.log" -exec tail -1 {} \;  | tail -10

Code (Text):

curl -Iv https://nginx.org/en/download.html

For posting code you might want to use CODE tags for code How to use forum BBCODE code tags

On a few of my slower login servers with 123.09beta01, I am seeing it hang around nginx version check

process listing output command

Code (Text):

ps aufxw

shows at hang time

Code (Text):

root     22322  0.0  0.0   9516  1728 pts/1    S+   17:07   0:00              |   \_ /bin/bash /usr/local/bin/dmotd
root     22323  0.0  0.1 152536  4504 pts/1    S+   17:07   0:00              |       \_ curl -sL https://nginx.org/en/download.html
root     22324  0.0  0.0   9096   892 pts/1    S+   17:07   0:00              |       \_ grep -E -o nginx\-[0-9.]+\.tar[.a-z]*
root     22325  0.0  0.0   9876   964 pts/1    S+   17:07   0:00              |       \_ awk -F nginx- /.tar.gz$/ {print $2}
root     22326  0.0  0.0  13324  1592 pts/1    S+   17:07   0:00              |       \_ sed -e s|.tar.gz||g
root     22327  0.0  0.0   4324   644 pts/1    S+   17:07   0:00              |       \_ head -n 1
root     22319  0.0  0.0   4316   704 pts/1    S+   17:07   0:00              \_ tee /root/centminlogs/cmm-login-git-checks_280617-170709.log

so will check that too for me it was IPv6 networking related which I should of disabled but it was enabled

Code (Text):

curl -Iv https://nginx.org/en/download.html
* About to connect() to nginx.org port 443 (#0)
*   Trying 2606:7100:1:69::3f...
* Connection timed out
*   Trying 2001:1af8:4060:a004:21::e3...
* Connection timed out
*   Trying 206.251.255.63...
* Connected to nginx.org (206.251.255.63) port 443 (#0)

to disable IPv6 add to the bottom of /etc/sysctl.conf these 2 lines

Code (Text):

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

then update via

Code (Text):

sysctl -p

also set in persistent config file /etc/centminmod/custom_config.inc the variable

Code (Text):

DISABLE_IPVSIX='y'

recheck and fast now connecting via IPv4 ip for nginx.org

Code (Text):

 curl -Iv https://nginx.org/en/download.html
* About to connect() to nginx.org port 443 (#0)
*   Trying 95.211.80.227...
* Connected to nginx.org (95.211.80.227) port 443 (#0)

I tried re-enabling IPv6 removing the 2 added /etc/sysctl.conf and rebooted my server to see if it was network related and that fixed it for IPv6 connection to nginx.org and allowed fast ssh login to Centmin Mod 123.09beta01 based server as for me it was related to IPv6 issues

Code (Text):

curl -Iv https://nginx.org/en/download.html
* About to connect() to nginx.org port 443 (#0)
*   Trying 2606:7100:1:69::3f...
* Connected to nginx.org (2606:7100:1:69::3f) port 443 (#0)

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Another reason for slow SSH logins is due to the login Centmin Mod Git repo update check to alert you to updates available for Centmin Mod code at /usr/local/src/centminmod. SSH logins will be slower if there are actually Git updates available. You can thus speed up SSH logins if you setup Centmin Mod code at /usr/local/src/centminmod to auto update via cronjob outlined at https://community.centminmod.com/threads/cronjob-auto-updating-centmin-mod-code-guide.3398/. If cronjob auto updates the code, SSH login check for updates will go faster as there is no updates to check for.

Example cmupdate cronjob

Code (Text):

41 3 * * * /usr/bin/cmupdate >/dev/null 2>&1

An example of how having Centmin Mod Github updates available will slow SSH login due to Centmin Mod code update check

SSH login shows Centmin Mod cod updates are available

Code (Text):

===============================================================================
 Centmin Mod code updates available for /usr/local/src/centminmod
 to update, run cmupdate command in SSH & re-run centmin.sh once & exit
===============================================================================

Checking the Git/Nginx check time for this SSH login shows 33.0569 seconds.

Code (Text):

find /root/centminlogs/ -type f -name "cmm-login-git-checks_*.log" -exec tail -1 {} \;
Total Git & Nginx Check Time: 17.064325247 seconds
Total Git & Nginx Check Time: 18.788097993 seconds
Total Git & Nginx Check Time: 1.928730724 seconds
Total Git & Nginx Check Time: 16.911994785 seconds
Total Git & Nginx Check Time: 24.150637742 seconds
Total Git & Nginx Check Time: 26.023300208 seconds
Total Git & Nginx Check Time: 33.056937890 seconds

Now if you run cmupdate to update Centmin Mod code

Code (Text):

cmupdate
No local changes to save
Updating da5daa1..11242b2
Fast-forward
 addons/ffmpeg.sh          | 32 ++++++++++++++++++++++++++++----
 centmin-cli.sh            |  6 +++---
 centmin.sh                |  6 +++---
 example/custom_config.inc |  4 ++--
 inc/nginx_configure.inc   | 35 ++++++++++++++++++++---------------
 inc/openssl_install.inc   |  2 +-
 inc/php_configure.inc     | 10 ++++++++--
 inc/php_upgrade.inc       |  7 +++++++
 inc/phpsededit.inc        |  2 +-
 9 files changed, 73 insertions(+), 31 deletions(-)

Relogin via SSH, check Git check time is now 1.6944s instead.

Code (Text):

find /root/centminlogs/ -type f -name "cmm-login-git-checks_*.log" -exec tail -1 {} \;
Total Git & Nginx Check Time: 17.064325247 seconds
Total Git & Nginx Check Time: 18.788097993 seconds
Total Git & Nginx Check Time: 1.928730724 seconds
Total Git & Nginx Check Time: 16.911994785 seconds
Total Git & Nginx Check Time: 24.150637742 seconds
Total Git & Nginx Check Time: 26.023300208 seconds
Total Git & Nginx Check Time: 33.056937890 seconds
Total Git & Nginx Check Time: 1.694455829 seconds