Archive for the ‘SysAdmin’ Category

Corrupt kernel update breaks mkinitrd – cannot boot

We were trying to install a QLogic card and it’s drivers on one of our SLES11 servers this morning and mkinitrd kept barking at us: lebsvn2:/boot/grub # mkinitrd -v Kernel image:   /boot/vmlinuz-2.6.27.19-5-default Initrd image:   /boot/initrd-2.6.27.19-5-default Root device: /dev/root (mounted on / as ext3) Resume device: /dev/disk/by-id/scsi-SATA_FUJITSU_MHZ2080_K85CT9925KBH-part3 (/dev/sda3) Device root not found in sysfs [...]

Simple file backup script for sysadmins

A friend of mine, Tony Krch, wrote this nearly ten years ago and I’ve used it ever since.  When ever I edit a system config file, like /etc/named.conf, I first do cd /etc backup resolv.conf Then I edit.  The backup script makes a copy using “cp -a” of the file, puts it in a sub-directory [...]

SSL on Glassfishv2

We bought a real SSL cert for our OpenSSO server.  That means I need to “install it” on the Glassfishv2 installation that runs the OpenSSO app.  The new cert came with three other certs, that I now understand are the “chain” that legitimize our cert by associating it (somehow) with the external authority. After much [...]

nsswitch compat mode not compatible with our dev, dev1, dev2 “extended” group

At work, we have many Unix and Linux systems, so we use NIS to coordinate the authentication and authorization of users.  One of our Unix groups has so many members that the older Unix systems can’t “see” them all.  So, we split up the membership into a set of entries in the /etc/group file that [...]

Faster grepping with awk.

Turns out that for some cases, awking is much, much faster than grep. Just now, I wanted to know how many unique MAC addresses appeared in our DHCP server’s log file asking for a lease but not getting it.  There are a few ways to skin this cat.  What’s interesting is that some ways are [...]

Use pam_access.so to limit system access to members of a certain group or netgroup.

I’m building a cluster of 25 machines at work. Trying to get the Infiniband stuff to work on them – a dev found an annomoly in his benchmarking numbers and asked me to verify his work and look for trouble and so – I did. While I was doing it, I found some other users [...]

Whoa – weird load ave and cpu freq reports from openSUSE 10.3

Just built a cluster of 25 Dell systems for our developers. These are Dell 1435SC systems, each with a pair of Dell 1435SC and 8 GB RAM. We installed openSUSE 10.3 on them all, added the Ganglia gmond and also the OpenIB infiniband successor OFED. Handed them off to our developers to certify and they [...]

Great article for small business IT folks

When I saw this, I thought of a colleagues recent experience with his client’s servers being taken over through a weakness in VNC. It was a pretty scary experience for him and his client – everyone in our Upper Valley Freelancers group tried to help and the mail flew fast and frequently for a few [...]

Treason uncloaked

Plagued by these messages in your Linux server’s kernel log – kern.log? Finally tracked down a reasonable explanation this morning. Seems a bug was introduced in the kernel back in 2.6.8 and it causes, among other troubles, this error message: Jan 17 12:30:13 iml kernel: TCP: Treason uncloaked! Peer 134.48.120.88:3832/80 shrinks window 3881756777:3881761622. Repaired.Jan 21 [...]

Renaming a user’s profile folder in Windows.

If I want to rename a user from “Mike Diehn” to “mdiehn” Log the user out. Log in as an Administrator, preferably in the realm in which the user account is defined rather than simply in the local computer realm. Manage Local Users and GroupRename the user account, maybe fill in the Full Name and [...]