Systems Administration Problem Solvers
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Random UNIX Related Items
You are attempting to login to a Linux machine (probably CentOS) and your SSH sessions are instantly disconnected.
/var/log/secure shows various Signal 15 crashes and this error:
mm_request_send: write: Broken pipe
Your box has been hacked. Format and Reinstall.
Be sure to run “yum update” at frequent intervals to keep your servers/VMs up-to-date!!
You are receiving these errors:
Connect Error (2000) mysqld cannot connect to MySQL 4.1+ using old authenticationERROR 1275 (HY000): Server is running in –secure-auth mode, but ‘dbname’@’localhost’ has a password in the old format; please change the password to the new format
ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused (client option 'secure_auth' enabled)ERROR 1372 (HY000): Password hash should be a 16-digit hexadecimal number
Your system is definitely storing passwords in the new format. You are going crazy because your database is offline.
UPDATE mysql.user SET Password = PASSWORD(‘cheese’) WHERE User = ‘test’ AND Host = ‘localhost’;
UPDATE mysql.user SET plugin = ‘mysql_native_password’ WHERE User = ‘test’ AND Host = ‘localhost’;
flush privileges;
Convert squid log timestamps to a human readable format:
cat access.log | perl -p -e 's/^([0-9]*)/"[".localtime($1)."]"/e'
Looking to host a Squid server? Contact VMDK Hosting.
Use the following ‘awk’ command to remove all blank lines from a file:
awk ‘NF > 0’ filename
You have setup pfSense as a VM via the OVA.
Your VM that you want to filter its traffic is on a portgroup on a vSwitch with no uplink.
pfSense has 2 NICs – 1. WAN – Using a portgroup that has internet access 2. LAN – Using the same portgroup/vswitch as your VM that needs its traffic filtered.
Turn on promiscuous mode on all vSwitches being used by pfSense and the VM.
Traffic will not pass without promiscuous mode!
You have long removed SRM/vSphere replication.
You discovered a VM still had vSphere Replication enabled.
system has paused replication disk added to vm
Manually remove vSphere replication from vCenter
1. In a webbrowser go to: http://YOUR-vCenter Server/mob
2. Remove this extensions: “com.vmware.vcHms”
More information about MOB, and removing plugins from vCenter, here: http://www.viktorious.nl/2012/05/06/vcenter-howto-remove-a-plugin-from-the-plugin-manager/
Remove vSphere replication from the affected VM
1. vim-cmd vmsvc/getallvms |grep “NAME OF THE VM” <- You are merely looking for the VM’s ID # 2. vim-cmd hbrsvc/vmreplica.disable [VM #] More hbrsvc commands can be found here: http://www.virtuallyghetto.com/2011/07/hbr-host-based-replication-cli-for-srm.html
Are you looking for VMware Hosting that offers cross-site vSphere Replication? Contact VMDK Hosting
cd /usr/ports/emulators/open-vm-tools-nox11/
make all install
vi /etc/rc.conf
vmware_guest_vmblock_enable=”YES”
vmware_guest_vmhgfs_enable=”YES”
vmware_guest_vmmemctl_enable=”YES”
vmware_guest_vmxnet_enable=”YES”
vmware_guestd_enable=”YES”
vi /etc/ntp.conf
First line: tinker panic 0
vi /boot/loader.conf
kern.hz=100
vi /etc/sysctl.conf
kern.cam.da.retry_count=100
vmware-toolbox-cmd timesync disable
noop, is essentially a first-in first-out (FIFO) queue with no extra logic.
Each virtual machine can stop worrying about the disk, instead passing I/O requests along to the hypervisor to make a better decision about overall performance.
Add “elevator=noop” to the kernel parameters in your boot loader’s configuration in /etc/grub.conf
`echo noop > /sys/block/${DEVICE}/queue/scheduler`.
Set the default in your kernel config for all VM kernels you roll, with `CONFIG_DEFAULT_IOSCHED=”anticipatory”`.
psql
With psql cli:
vacuum full;
also do:
reindex
List off all the rules in order. This helps to see if an allow is overriding one of your denies:
iptables -nvL –line-numbers
Reject or Drop?
Drop means to drop everything at the interface and give no response. Best for port probes and the like.
Reject responds to the source. Best practices for TCP/IP