Finding Patterns

I know that most of my posts are of the nature "if you're trying to accomplish 'X' here's a way that you can do it". Unfortunately, this time, my post is more of a, "I've got yet to be solved problems going on". So, there's no magic bullet fix currently available for those with similar problems who found this article. That said, if you are suffering similar problmes, know that you're not alone. Hopefully that's small consolation and what follows may even help you in investigating your own problem.

Oh: if you have suggestions, I'm all ears. Given the nature of my configuration, there's not much in the way of useful information I've yet found via Google. Any help would be much appreciated...

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The shop I work for uses Symantec's Veritas NetBackup product to perform backups of physical servers. As part of our effort to make more of the infrastructure tools we use more enterprise-friendly, I opted to leverage NetBackup 7.1's NetBackup Access Control (NBAC) subsystem. On its own, it provides fine-grained rights-delegation and role-based access control. Horse it to Active Directory and you're able to roll out a global backup system with centralized authentication and rights-management. That is, you have all that when things work.

For the past couple months, we've been having issues with one of the dozen NetBackup domains we've deployed into our global enterprise. When I first began trougleshooting the NBAC issues, the authentication and/or authorization failures had always been associated with a corruption of LikeWise's sqlite cachedb files. At the time the issues first cropped up, these corruptions always seemed to coincide with DRS moving the NBU master server from one ESX host to another. It seemed like, when under sufficiently heavy load - the kind of load that would trigger a DRS event - LikeWise didn't respond well to having the system paused and moved. Probably something to do with the sudden apparent time-jump that happens when a VM is paused for the last parts of the DRS action. My "solution" to the problem was to disable automated-relocation for my VM.

This seemed to stabilize things. LikeWise was no longer getting corrupted and seems like I'd been able to stabilize NBAC's authentication and authorization issues. Well, they stabilized for a few weeks.

Unfortunately, the issues have begun to manifest themselves, again, in recent weeks. We've now had enough errors that some patterns are starting to emerge. Basically, it looks like something is horribly bogging the system down around the time that the nbazd crashes are happening. I'd located all the instances of nbazd crashing from its log files ("ACI" events are loged to the /usr/openv/netbackup/logs/nbazd logfiles), and then began to try correlating them with system load shown by the host's sadc collections. I found two things: 1) I probably need to increase my sample frequency - it's currently at the default 10-minute interval - if I want to more-thoroughly pin-down and/or profile the events; 2) when the crashes have happened within a minute or two of an sadc poll, I've found that the corresponding poll was either delayed by a few seconds to a couple minutes or was completely missing. So, something is causing the server to grind to a standstill and nbazd is a casualty of it.

For the sake of thoroughness (and what's likely to have matched on a Google-search and brought you here), what I've found in our logs are messages similar to the following:

/usr/openv/netbackup/logs/nbazd/vxazd.log

07/28/2012 05:11:48 AM VxSS-vxazd ERROR V-18-3004 Error encountered during ACI repository operation.
07/28/2012 05:11:48 AM VxSS-vxazd ERROR V-18-3078 Fatal error encountered. (txn.c:964)
07/28/2012 05:11:48 AM VxSS-vxazd LOG V-18-4204 Server is stopped.
07/30/2012 01:13:31 PM VxSS-vxazd LOG V-18-4201 Server is starting.

/usr/openv/netbackup/logs/nbazd/debug/vxazd_debug.log

07/28/2012 05:11:48 AM Unable to set transaction mode. error = (-1)
07/28/2012 05:11:48 AM SQL error S1000 -- [Sybase][ODBC Driver][SQL Anywhere] Connection was terminated
07/28/2012 05:11:48 AM Database fatal error in transaction, error (-1)
07/30/2012 01:13:31 PM _authd_config.c(205) Conf file path: /usr/openv/netbackup/sec/az/bin/VRTSaz.conf
07/30/2012 01:22:40 PM _authd_config.c(205) Conf file path: /usr/openv/netbackup/sec/az/bin/VRTSaz.conf

Our NBU master servers are hosted on virtual machines. It's a supported configuration and adds a lot of flexibility and resiliency to the overall enterprise-design. It also means that I have some additional metrics available to me to check. Unfortunately, when I checked those metrics, while I saw utilization spikes on the VM, those spikes corresponded to healthy operations of the VM. There weren't any major spikes (or troughs) during the grind-downs. So, to ESX, the VM appeared to be healthy.

At any rate, I've requested our ESX folks see if there might be anything going on on the physical systems hosting my VM that aren't showing up in my VM's individual statistics. I'd previously had to disable automated DRS actions to keep LikeWise from eating itself - those DRS actions wouldn't have been happening had the hosting ESX system not been experiencing loading issues - perhaps whatever was causing those DRS actions is still afflicting this VM.

I've also tagged one of our senior NBU operators to start picking through NBU's logs. I've asked him to look to see if there are any jobs (or combinations of jobs) that are always running during the bog-downs. If it's a scheduling issue (i.e., we're to blame for our problems), we can always reschedule jobs to exert less loading or we can scale up the VM's memory and/or CPU reservations to accommodate such problem jobs.

For now, it's a waiting-game. At least there's an investigation path, now. It's all in finding the patterns.

When VMs Go *POOF!*

Like many organizations, the one I work for is following the pathway to the cloud. Right now, this consists of moving towards an Infrastructure As A Service model. This model heavily leverages virtualization. As we've been pushing towards this model, we've been doing the whole physical to virtual dance, wherever possible.

In many cases, this has worked well. However, like many large IT organizations, we have found some assets on our datacenter floors that have been running for years on both outdated hardware and outdated operating systems (and, in some cases, "years" means "in excess of a decade"). Worse, the people that set up these systems are often no longer employed by our organization. Worse still, the vendors of the software in use long-ago discontinued either the support of the software version in use or no longer maintain any version of the software.

One such customer was migrated last year. They weren't happy about it at the time, but, they made it work. Because we weren't just going to image their existing out of date OS into the pristine, new environment, we set them up with a virtualized operating environment that was as close to what they'd had as was possible. Sadly, what they'd had was a 32bit RedHat Linux server that had been built 12 years previously. Our current offerings only go back as far as RedHat 5, so that's what we built them. While our default build is 64bit, we offer 32bit builds - unfortunately, the customer never requested a 32bit environment The customer did their level best to massage the new environment into running their old software. Much of this was done by tar'ing up directories on the old system and blowing them onto their new VM. They'd been running on this massaged system for nearly six months.

If you noticed that 32-to-64bit OS-change, you probably know where this is heading...

Unfortunately, as is inevitable, we had to take a service outage across the entire virtualized environment. We don't yet have the capability in place to live migrate VMs from one data center to another for such windows. Even if we had, the nature of this particular outage (installation of new drivers into each VM) was such that we had to reboot the customer's VM, any way.

We figured we were good to go as we had 30+ days of nightly backups of each impacted customer VM. Sadly, this particular customer, after doing the previously-described massaging of their systems, had never bothered to reboot their system. It wasn't (yet) in our procedures to do a precautionary pre-modification reboot of the customers' VMs. The maintenance work was done and the customer's VM rebooted. Unfortunately, the system didn't come back from the reboot. Even more unfortunately, the thirty-ish backup images we had for the system were similarly unbootable and, worse, unrescuable.

Eventually, we tracked down the customer to inform them of the situation and to find out if the system was actually critical (the VM had been offline for nearly a full week by the time we located the system owner, but no angry "where the hell is my system" calls had been received or tickets opened). We were a bit surprised to find that this was, somehow, a critical system. We'd been able to access the broken VM to a sufficient degree to determine that it hadn't been rebooted in nearly six months, that it's owner hadn't logged in nearly that same amount of time but that the on-disk application data appeared to be intact (the filesystems they were on were mountable without errors). So, we were able to offer the customer the option of building them a new VM and helping them migrate their application data off the old VM to the new VM.

We'd figured we'd just restore data from the old VM's backups to a directory tree on the new VM. The customer, however, wanted the original disks back as mounted disks. So, we had to change plans.

The VMs we build make use of the Linux Volume Manager software to manage storage allocation. Each customer system is built off of standard templates. Thus, each VM's default/root volume groups all share the same group name. Trying to import another host's root volume group onto a system that already has a volume group of the same name tends to be problematic in Linux. That said, it's possible to massage (there's that word again) things to allow you to do it.

The customer's old VM wasn't bootable to a point where we could simply FTP/SCP its /etc/lvm/backup/RootVG file off. The security settings on our virtualization environment also meant we couldn't cut and paste from the virtual console into a text file on one of our management hosts. Fortunately, our backup system does support file-level/granular restores. So, we pulled the file from the most recent successful backup.

Once you have an /etc/lvm/backup/<VGNAME> file available, you can effect a name change on a volume group relatively easily. Basically, you:

1. Create your new VM
2. Copy the old VM's  /etc/lvm/backup/<VGNAME> into the new VM's /etc/lvm/backup directory (with a new name)
3. Edit that file, changing the old volume group's object names to ones that don't collide with the currently-booted root volume groups (really, you only need to change the name of the root volume group object - the volumes can be left as is
4. Connect the old VM's virtual disk to the new VM
5. Perform a rescan of the VM's scsi bus so it sees the old VM's virtual disk
6. Do a `vgcfgrestore -f  /etc/lvm/backup/<VGNAME> <NewVGname>` 
7. Do a `pvscan`
8. Do a `vgscan`
9. Do a `vgchange -ay <NewVGname>`
10. Mount up the renamed volume group's volumes

As a side note (to answer "why didn't you just do a `boot linux rescue` and change things that way"): our security rules prevent us from keeping bootable ISOs (etc.) available to our production environment. Therefore, we can't use any of the more "normal" methods for diagnosing or recovering a lost system. Security rules trump diagnostics and/or recoverability needs. Dems da breaks.

Asymmetrical NIC-bonding

Currently, the organization I am working for is making the transition from 1Gbps networking infrastructure to 10Gbps infrastructure. The initial goal had been to first migrate all of the high network-IO servers that were using trunked 1Gbps interfaces to using 10Gbps Active/Passive configurations.
Given the current high per-port cost of 10Gbps networking, it was requested that a way be found to not waste 10Gbps ports. Having a 10Gbps port sitting idle "in case" the active port became unavailable was seen as financially wasteful. A a result, we opted to pursue the use of asymmetrical A/P bonds that used our new 10Gbps links for the active/primary path and reused our 1Gbps infrastructure for the passive/failover path.

Setting up bonding on Linux can be fairly trivial. However, when you start to do asymmetrical bonding, you want to ensure that your fastest paths are also your active paths. This requires some additional configuration of the bonded pairs beyond just the basic declaration of the bond memberships.
In a basic bonding setup, you'll have three primary files in the /etc/sysconfig/network-scripts directory: ifcfg-ethX, ifcfg-ethY and ifcfg-bondZ. The ifcfg-ethX and ifcfg-ethY files are basically identical but for their DEVICE and HWADDR parameters. At their most basic, they'll each look (roughly) like:

DEVICE=ethN
HWADDR=AA:BB:CC:DD:EE:FF
ONBOOT=yes
BOOTPROTO=none
MASTER=bondZ
SLAVE=yes

And the (basic) ifcfg-bondZ file will look like:

DEVICE=bondZ
ONBOOT=yes
BOOTPROTO=static
NETMASK=XXX.XXX.XXX.XXX
IPADDR=WWW.XXX.YYY.ZZZ
MASTER=yes
BONDING_OPTS="mode=1 miimon=100"

This type of configuration may produce the results you're looking for, but it's not guaranteed to. If you want to absolutely ensure that your faster NIC will be selected as the primary NIC (and that it will fail back to that NIC in the event that the faster NIC goes offline and then back online), you need to be a bit more explicit with your ifcfg-bondZ file. To do this, you'll mostly want to modify your BONDING_OPTS directive. I also tend to add some BONDING_SLAVEn directives, but that might be overkill. Your new ifcfg-bondZ file that forces the fastest path will look like:

DEVICE=bondZ

ONBOOT=yes

BOOTPROTO=static

NETMASK=XXX.XXX.XXX.XXX

IPADDR=WWW.XXX.YYY.ZZZ

MASTER=yes

BONDING_OPTS="mode=1 miimon=100 primary=ethX primary_reselect=1"

The primary= tells the bonding driver to set the ethX device as primary when the bonding-group first onlines. The primary_reselect= tells it to use a interface selection policy of "best".

Note: The default policy is "0". This policy simply says "return to interface declared as primary". I choose to override with policy "1" as a hedge against the primary interface coming back in some kind of degraded state (while most of our 10Gbps media is 10Gbps-only, some of the newer ones are 100/1000/1000). I only want to fail back to the 10Gbps interface if it's still running at 10Gbps and hasn't for some reason, negotiated down to some slower speed.

When using the more explicit bonding configuration, the resultant configuration will resemble something like:

Ethernet Channel Bonding Driver: v3.4.0-1 (Octobber 7, 2008)

Bonding Mode: fault-tolerance (active-backup)

Primary Slave: ethX (primary_reselect better)

Currently Active Slave: ethX

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: ethX

MII Status: up

Speed: 10000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: AA:BB:CC:DD:EE:FF

Slave Interface: ethY

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: FF:EE:DD:CC:BB:AA

ACL Madness

In our environment, security is a concern. So, many programs and directories that you might take being available to you on a "standard" Linux system will give you a "permission denied" on one of our systems. Traditionally, you might work around this by changing the group-ownership and permissions on the object to allow a subset of the system users the expected level of access to those files or directories. And, this will work great if all the people that need access share a common group. If they don't you have to explore other avenues. One of these avenues is the extened permissions attributes found in Linux's ACL handling (gonna ignore SELinux, here, mostly because: A) I'm lazy; B) I freaking hate SELinux - probably because of "A"; and, C) ACLs are a feature that is available across different implementations of UNIX and Linux, and is thus more portable than SELinux or other vendor-specific extended security attribute mechanisms). Even better, as a POSIX filesystem extension, you can use it on things like NFS shares and have your ACLs work across systems and *N*X platforms (assuming everone implements the POSIX ACLs the same way).

And, yes, I know things like `sudo` can be used to delegate access, but that's fraught with its own concerns, as well, least of all its lack of utility for users that aren't logging in with interactive shells.

Say you have a file <tt>/usr/local/sbin/killmenow</tt> that is currently set to mode 700 and you want to give access to it to members of the ca_opers and md_admins groups. You can do something like:

# setfacl -m g:ca_opers:r-x /usr/local/sbin/killmenow
# setfacl -m g:md_admins:r-x /usr/local/sbin/killmenow

Now, members of both the ca_opers and md_admins groups can run this program.

All is well and good until someone asks, "what files have had their ACLs modified to allow this" and you've (or others on your team) gone crazy with the setfacl command. With standard file permissions, you can just use the `find` command to locate files that have a specific permissions-setting. With ACLs, `find` is mostly going to let you down. So, what to do? Fortunately,  setfacl 's partner-command, `getfacl ` can come to your rescue. Doing something like

# getfacl --skip-base -R 2> /dev/null | sed -n 's/^# file://p`

Will walk the directory-structure, from downward, giving you a list of files with ACLs added to them. Once you've identified such-modified files, you can then run `getfacl` against them, individually, to show what the current ACLs are.

FaceBook Security Fail

Ok, this is a bit of a departure from my usual, work-related posting. That said, security fits into the rubric of "more serious postings", even if that security is related to social networks. Who knows: maybe I'll decide to move it, later. At any rate...

 

I'm a big fan of social networking. In addition to my various blogs (on Posterous, BlogSpot, Tumblr, etc.), I make heavy use of services like FaceBook, Plus and Twitter (and have "personal" and "work" personnae set up on each). On some services (FaceBook and LiveJournal)  I run my accounts fairly locked-down; on others (most everything else), I run things wide-open. In either case, I'm not exactly the most censored of individuals. The way I look at it, if someone's going to use my postings against me, I may as well make it easy for them to do it up front than to put myself in a position where I'm invested in an individual or an organization only to have my posting history negatively subsequently sabotage that. It's a pick your poison kind of thing.

That said, not everyone is quite as laissez-faire about their online sharing activities. So, in general, I prefer to keep my stuff at least as locked down as the members of my sharing community do. That way, there's a lower likelihood that my activities will accidentally compromise someone else.

Today, a FaceBook friend of mine was trying to sort through they myriad security settings available to her so that she could create a "close friends only" kind of profile. She'd thought that she'd gotten things pretty locked down, until an unexpected personal message revealed to her that she had information leakage, somewhere, in her FaceBook usage. I was trying to help her ID it.

While my friend had fairly restrictively locked down her profile, she wasn't aware that certain actions could compromise those settings. Specifically, she wasn't aware that if she posted a comment to a public (or at least more open) thread, that others would be able to "see her". She'd assumed that if she set all of her security buttons-n-dials to "friends only" that anything she did would be kept friends only. With FaceBook, that's mostly the case. However, if you comment on a thread started by another friend, then everyone who is able to see that thread can "see" (aspects of) you, as well. Thus, if a friend starts a thread and has the permissions set to public and you comment on it, the entire Internet can see that you have some kind of FaceBook presence, even if they don't have permission to view your profile/timeline.

In attempting to illustrate this, I took a screen capture of a post that had been set to public. I'd done so using the post of someone I thought was a shared friend (when I'd clicked on the poster's profile, both myself and my security-conscious friend appeared to show up in the poster's "mutual friends" list). It turns out I was mistaken in that thought.

When I'd posted the screen shot to my security-conscious friend's wall, I tagged the original poster in that wall post. My security-conscious friend had set her wall to "friends only". When she informed me that the public-poster was not a mutual "friend" but a "friend of a friend", I'd made the suppostion that the tagging of the public-posting friend would be moot. After all: what kind of security model would allow me to overrided my security-conscious friend's wall security settings with something so simple as a tag-event? Turns out, FaceBook's security model would. To me, that would fall into the general heading of a "broken security model".

Oh well, now to figure out how to rattle some cages in FaceBook's site usability group to get them to fix that.

AD Integration Woes

For a UNIX guy, I'm a big fan of leveraging Active Directory form centralized system and user management purposes. For me, one of the big qualifications for any application/device/etc. to be able to refer to itself as "enterprise" is that it has to be able to pull user authentication information via Active Directory. I don't care whether it does it the way that Winbind-y things do, or if they just pull data via Kerberos or LDAP. All I care is that I can offload my user-management to a centralized source.

In general, this is a good thing. However, like many things that are "in general, a good thing" it's not always a good thing. If you're in an enterprise that's evolving it's Active Directory infrastructure, tying things to AD means that you're impacted when AD changes or breaks. Someone decides, "hey, we need to reorganize the directory tree" and stuff can break. Someone decides, "hey, we need to upgrade our AD servers from 2003 to 2008" and stuff can break.

Recently, I started getting complaints from the users of our storage resource management (SRM) system that they couldn't login any more. It'd been nearly a year since I'd set it up, so sorting it out was an exercise in trying to remember what the hell I did ...and then Googling.

The application, itself, runs on a Windows platform. The login module that it uses for centralized authentication advertises itself as "Active Directory". In truth, the login module is a hybrid LDAP/Kerberos software module. Even though it's a "Windows" application, they actually use the TomCat Java server for the web UI (and associated login management components). TomCat is what uses Kerberos for authentication data.

Sometime in recent months, someone had upgraded Active Directory. Users that had been using the software before the AD-upgrade were able to authenticate, just fine. Users that had tried to start using the software after the AD-upgrade couldn't get in. Turns out that, when Active Directory had gotten upgraded, the encryption algorithms had gotten changed. Ironically, I didn't find the answer to my problem in any of the forums related to the application: I found it in the forums for another application that used TomCat's Kerberos components.

To start the troubleshooting process, one needs to first modify TomCat's bsclogin.conf file. Normally, this file is only used to tell TomCat where to find the Kerberos configuration file. However, if you modify your bsclogin.conf file and add the directive "debug=true" to it like so:

     com.sun.security.auth.module.Krb5LoginModule required debug=true;

Enhanced user login debugging messages are enabled. Once this is added and tomcat is restarted, login-related messages will start showing up in your ${TOMCATHOME}/logs/stdout.log file. What started showing up in mine were messages like:

     [Krb5LoginModule] user entered username: thjones2@SRMdomain.NET
Acquire TGT using AS Exchange

     [Krb5LoginModule] authentication failed KDC has no support for encryption type (14)

With this error message in hand, I was able to find out that TomCat's Kerberos modules were using the wrong encryption routines to get data out of Active Directory. The fix was to update my Kerberos initialization file and add the following two lines to my [libdefaults] stanza (I just added it right after the dns_lookup_realm line and before the next stanza of directives):

     default_tkt_enctypes = rc4-hmac
     default_tgs_enctypes = rc4-hmac

Making this change (and restarting TomCat) resulted in the failing users suddenly being able to get in.

I'd normally rag on my Windows guys for this, but, the Windows guys aren't exactly used to providing AD-related service notifications to anyone but Windows users. This application, while (currently) running on a Windows platform, isn't something that's traditionally thought of as AD-reliant. Factor in that true, native AD modules pretty much just auto-adjust to such changes, and it didn't occur to them to notify us of the changes.

Oh well. AD-integration is a learning experience for everyone involved, I suppose.

Cross-Platform Sharing Pains

All in all, the developers of Linux seem to have done a pretty good job of ensuring that Linux is able to integrate with other systmes. Chief among this integration has been in the realm of sharing files between Linux and Windows hosts. Overall, the CIFS support has been pretty damned good and has allowed Linux to lead in this area compared to other, proprietary *N*X OSes.

That said, Microsoft (and others) seem to like to create a moving target for the Open Source community to aim at. If you have Windows 2008-based fileservers in your operations and are trying to get you Linux hosts to mount shares coming off these systems, you hay have run into issues with doing so. This is especially so if your Windows share-servers are set up with high security settings and you're trying to use service names to reference those share servers (i.e., the Windows-based fileserver may have a name like "dcawfs0035n" but you might have an alias like "repository5").

Normally, when mounting a CIFS fileserver by its real name, you'll do something like:

# mount -t cifs "//dcawfs0035n/LXsoftware" /mnt/NAS -o domain=mydomain,user=myuser

And, assuming the credentials you supply are correct, the URI is valid and the place you're attemtping to mount to exists and isn't busy, you'll end up with that CIFS share mounted on your Linux host. However, if you try to mount it via an alias (e.g., a CNAME in DNS):

# mount -t cifs "//repository5/LXsoftware" /mnt/NAS -o domain=mydomain,user=myuser

You'll get prompted for your password - as per normal - but, instead of being rewarded with the joy of your CIFS share mounted to you Linux host, you'll get an error similar to the following:

mount error 5 = Input/output error
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)

Had you fat-fingered your password, you'd have gotten a "mount error 12" (permission denied), instead. The above results in strict name checking being performed on the share mount attempt. Because you've attempted to an alias to connect with, the name-checking will fail and you'll get the above denial. You can verify that this is the underlying cause by re-attempting the mount with the fileserver's real name. If that succeeds where the alias, failed, you'll know where to go, next.

The Microsoft-published solution is found in KB281308. To summarize, you'll need to:

• Have admin and login rights on the share-server
• Login to the share-server
• Fire up regedit
• Navigate to "HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters"
• Create a new DWORD paramter named "DisableStrictNameChecking"
• Set its value to "1"
• Reboot the fileserver
• Retry your CIFS mount attempt.

At this point, your CIFS mount should succeed.

Interestingly, if you've ever tried to connect to this share from another Windows host not in the share-server's domain (e.g., from a host on different Windows domain that doesn't have cross-realm trusts set up or a standlone Windows client), you will probably have experienced connection errors, as well. Typical error messages being something on the order of "account is not allowed to logon from this resource" or just generally refusing to accept what you know to be a good set of credentials.

Quick-n-Dirty Yum Repo via HTTP

Recently, we had a bit of a SNAFU in the year-end renewal of our RedHat support. As a result, all of the RHN accounts tied to the previous contract lost access to RHN's software download repositories. This meant that things like being able to yum-down RPMs on rhn_register'ed systems no longer worked and, we couldn't log into RHN and do a manual download, either.

Fortunately, because we're on moderately decent terms with RedHat and they know that the contract eventually will get sorted out, they were willing to help us get through our current access issues. Moving RHN accounts from one permanent contract to another, after first associating them with some kind of temporary entitlement is a paperwork-hassle for all parties involved and is apt to get your account(s) mis-associated down the road. Since all parties knew that this was a temporary problem but needed an immediate fix, our RedHat representative furnished us with the requisite physical media necessary to get us through till the contracts could get sorted out.

Knowing that I wasn't the only one that might need the software and that I might need to execute some burndown-rebuilds on a particular project I was working on, I wanted to make it easy to pull packages to my test systems. We're in an ESX environment, so, I spun up a small VM (only 1GB of virtual RAM, 1GHz of virtual CPU, a couple Gigabytes of virtual disk for a root volume and about 20GB of virtual disk to stage software onto and build an RPM repository on) to act as a yum repository server.

After spinning this basic VM, I had to sort out what to do as far as getting that physical media turned into a repo. I'm not a big fan of copying CDs as a stream of discrete files (been burned, too many times, by over-the-wire corruption, permission issues and the like). So, I took the DVD and made an ISO from it. I then took that ISO and scp'ed it up to the VM.

Once I had the ISO file copied up to the VM, did a quick mount of it (`mount -t iso9660 -o loop,ro /tmp/RHEL5.7_x86_64.iso /mnt/DVD` for those of you playing at home). Once I mounted it, I did a quick copy of its contents to the filesystem I'd set aside for it. I'm kind of a fan of cpio for things like this, so I cd'ed into the root of the mounted ISO and did a `find . -print | cpio -pmd /RepoDir` to create a good copy of my ISO data into a "real" filesystem (note, you'll want to make sure you do a `umask 022` first to ensure that the permission structures from the mounted ISO get copied, intact, along with the files, themselves).

With all of the DVD's files copied to the repo-server and into a writeable filesystem, it's necessary to create all the repo structures and references to support use by yum. Our standard build doesn't include the createrepo tool, so, first I had to locate its RPM in the repo filessytem and then install it onto my repo-server. Doing a quick `find . -name "*createrepo*rpm"` while cd'ed into repo fileystem turned up the path to the requisite RPM. I then did an `rpm -Uh [PathFromFind]` to install the  createrepo tool's RPM files.

The createrepo tool is a nifty little tool. You just cd into the root of the directory where you copied your media to, do a `createrepo .`, and it scans the directory structures to find all the RPMs and XMLs and other files and creates the requisite data structures and pointers that allow yum to know how to pull the appropriate RPMs from the filesystem.

Once that's done, if all you care about is local access to the RPMs, you can create a basic .repo file in /etc/yum.repos.d that uses a "baseurl=file:///Path/To/Media" directive in it.

In my case, I wanted to make my new repo available to other hosts at the lab. Easiest way to make the repo available over the network is to do so via HTTP. Our standard build doesn't include the standard RedHat HTTP server, by default. So, I manually installed the requisite RPMs from the repo's filesystem. I modified the stock /etc/httpd/conf/httpd.conf and added the folowing stanzas to it:

Alias /Repo/ "/RepoDir/"
<Directory "/RepoDir">
   Options Indexes MultiViews
   AllowOverride None
   Order allow,deny
   Allow from all
</Directory>

[Note: this is probably a looser configuration than I'd have in place if I was making this a permanent solution, but this was just meant as a quick-n-dirty workaround for a temporary problem.]

I made sure to do a `chkconfig httpd on` and then did a `service httpd start` to activate the web server. I then took my web browser and made sure that the repo filesystem's contents were visable via web client. It wasn't: I forgot that our standard build has port 80 blocked by default. I did the requisite juju to add an exception to iptables for port 80 and all was good to go.

With my RPMs (etc.) now visable via HTTP, I logged into the VM that I was actually needing to install RPMs to via yum. I escalated privileges to root and created an /etc/yum.repos.d/LAB.repo file that looked similar to the following:

[lab-repo]
name=RHEL 5.7
baseurl=http://repovm.domain.name/Repo
enabled=1
gpgcheck=0

I did a quick cleanup of the consuming VM's yum repo information with a `yum clean all` and then verified taht my consuming VM was able to properly see the repos's data by doing a `yum list`. All was good to go. Depending on how temporary this actually ends up being, I'll go back and make my consuming VM's .repo file a bit more "complete" and more properly layout the repo-server's filesystem and HTTP config.

Who Cut Off My `finger`

Overall, I'm not trying to make this, my "more serious blog" a dumping-ground for rants. So, please forgive me this rant and please feel free to skip this post....

I've been using UNIX and similar systems for a long time, now. So, I'm kind of set in my ways in the things I do on systems and the tools I expect to be there. When someone capriciously removes a useful tool, I get a touch upset.

`finger` is one of those useful tools. Sadly, because people have, in the mists of time` misconfigured finger, security folks now like to either simply disable it or remove it altogether. Fine. Whatever: I appreciate that there might be security concerns. However, if you're going to remove a given command, at least make sure you're accomplishing something useful for the penalty you make system users pay in frustration and lost time. If you decide to remove the finger command, then you should probably also make it so I can't get the same, damned information via:

• `id`
• `who`
• `whoami`
• `last`
• `getent passwd <USERID>`
• (etc.)

If I can run all of those commands, I've still got all the ability to get the data you're trying to hide by removing `finger`. So, what have you accomplished other than to piss me off and make it so I have to get data via other avenues? Seriously: "WTF"?

Why the hell is it that, when someone reads a "security best practice", they go ahead and blindly implement something without bothering to ask the next, logical questions: "does doing this, by itself, achieve my security goal," "is the potential negative impact on system users more than balanced-out by increased system security", "is there a better way to do this and achieve my security goals" and "what goal am I actually acheiving by taking this measure." If you don't ask these questions (and have good, strong answers to each), you probably shouldn't be following these "best practices."

NetBackup with Active Directory Authentication on UNIX Systems

While the specific hosts that I used for this exercise were all RedHat-based, it should work for any UNIX platform that both NetBackup 6.0/6.5/7.0/7.1 and Likewise Open are installed onto.

I'm a big fan of leveraging centralized-authentication services wherever possible. It makes life in a multi-host environment - particularly where hosts can number from the dozens to the thousands - a lot easier when you only have to remember one or two passwords. It's even more valuable in modern security environments where policies require frequent password changes (or, if you've even been through the whole "we've had a security incident, all the passwords on all of the systems and applications need to be changed, immediately" exercise). Over the years, I've used things like NIS, NIS+, LDAP, Kerberos and Active Directory to do my centralized authentication. If your primary platforms are UNIX-based, NIS, NIS+, LDAP and Kerberos have traditionally been relatively straight-forward to set up and use.

I use the caveat of "relatively" because, particularly in the early implementations of each service, things weren't always dead-simple. Right now, we seem to be mid-way through the "easiness" life-cycle of using Active Directory as a centralized authentication source for UNIX operating systems and UNIX-hosted applications. Linux and OSX seem to be leading the charge in the OS space for ease of integration via native tools. There's also a number of third-party vendors out there who provide commercial and free solutions to do it for you, as well. In our enterprise, we chose LikeWise, because, at the time, it was the only free option that also worked reasonably-well with our large and complex Active Directory implementation. Unfortunately, not all of the makers of software that runs on the UNIX hosts seem to have been keeping up on the whole "AD-integration within UNIX operating environment" front.

My latest pain in the ass, in this arena, is Veritas NetBackup. While Symantec likes to tout the value of NetBackup Access Control (NBAC) in a multi-administrator - particularly one where different administrators may have radically different NetBackup skill sets or other differentiating factors - using it in a mixed-platform environment is kind of sucktackular to set up. While modern UNIX systems have the PAM framework to make writing an application's authentication framework relatively trivial, Symantec seems to still be stuck in the pre-PAM era. NBAC's group lookup components appear to still rely on direct consultation of a server's locally-maintained group files rather than just doing a call to the host OS's authentication frameworks.

When I discovered this problem, I opened a support case with Symantec. Unfortunately, their response was "set up a Windows-based authentication broker". My NetBackup environment is almost entirely RedHat-based (actually, unless/until we implement BareMetal Restore (BMR) or other backup modules that require specific OSes be added into the mix, it is entirely RedHat-based). The idea of having to build a Windows server just to act as an authentication broker struck me as a rather stupid way to go about things. It adds yet another server to my environment and, unless I cluster that server, it introduces a single point of failure into and otherwise fairly resilient NetBackup design. I'd designed my NetBackup environment with a virtualized master server (with DRS and SRM supporting it) and multiple media servers for both throughput and redundancy

We already use LikeWise Open to provide AD-base user and group management service for our Linux and Solaris hosts. When I first was running NetBackup through my engineering process, using the old Java auth.conf method for login management worked like a champ. The Java auth.conf-based systems just assumes that any users trying to access the Java UI are users that are managed through /etc/passwd. All you have to do is add the requisite user/rights entries into the auth.conf file and Java treats AD-provided users the same as it treats locally-managed users. Because of this, I suspected that I could work around Symantec's authorization coding lameness.

After a bit of playing around with NBAC, I discovered that, so long as the UNIX group I wanted to map rights to existed in /etc/group, NBAC would see it as a valid, mappable "UNIX PWD" group. I tested by seeing if it would at least let me map the UNIX "wheel" group to one of the NBAC privilege groups. Whereas, even if I could look up the group via getent, if it didn't exist in /etc/group, NBAC would tell me it was an invalid group. Having already verified that a group's presence in /etc/group allowed NBAC to use a group, I proceded to use getent to copy my NetBackup-related groups out of Active Directory and into my /etc/group file (all you have to do is a quick `getent [GROUPNAME] >> /etc/group` and you've populated your /etc/group file).

Unfortunately, I didn't quite have the full groups picture. When I logged in using my AD credentials, I didn't have any of the expected mapped-privileges. I remembered that I'd explicitly emptied the userids from the group entries I'd added to my /etc/group file (I'd actually sed'ed the getents to do it ...can't remembery why, at this point - probably just anticipating the issue of not including userids in the /etc/group file entries). So, I logged out of the Java UI and reran my getent's - this time leaving the userids in place. I logged back into the Java UI and this time I had my mapped privileges. Eureka. 

Still I wasn't quite done. I knew that, if I was going to roll this solution into production, I'd have to cron-out a job to keep the getent file up-to date with the changing AD group memberships. I noticed, while nuking my group entry out of getent, that only my userid was on the group line and not every member of the group. Ultimately, tracked it down to LikeWise not doing full group enumeration by default. So, I was going to have to force LikeWise to enumerate the group's membership before running my getent's.

I proceded to dig around in /opt/likewise/bin for likely candidates for forcing the enumeration. After trying several lw*group* commands, I found that doing a `lw-find-group-by-name [ADGROUP]` did the trick. Once that was run, my getent's produced fully-populated entries in my /etc/group file. I was then able to map rights to various AD groups and wrote a cron script to take care keeping my /etc/group file in sync with Active Directory.

In other words, I was able to get NBAC to work with Active Directory in an all RedHat environment and no need to set up a Windows server just to be an authentication broker. Overall, I was able to create a much lighter-weight, portable solution.