server – Chris Paquin

The Homelab Dilemma: Living With Enterprise Servers

03/22/2026

Enterprise Servers are loud and hot, and while a couple of 13th generation Dell servers kept a room nice and toasty in the cold of winter, it a double whammy to your electric bill in the Spring/Summer.

The noise can be problematic as well, especially since I no longer have a basement, where I relied on my servers to circulate and dehumidify the stuffy air. Now, I actually have to sit in a room with the rack. Which is why I moved it to the bedroom. Strange.

So why the bedroom, well the white noise (when under control) helps me sleep and I can turn down the heat in the Winter and not freeze at night. And in the day, when I power everything up, I am in my home office (or my second home office – the dinning room), which is already loud enough with my workstations and old Cisco switches. That tiny home office, that is technically a small bedroom for your least favorite child, can get downright uncomfortably warm.

Why So Much Noise

As anyone who has worked in a datacenter can tell you. Servers are loud. Let compare fans in an Dell R630 to an R730.

Server	Form Factor	Effective fan size	Fan Count	Notes
Dell R630	1U	~40 mm blower	7	Very high RPM, loud, high static pressure
Dell R730	2U	~60 mm blower	6	Still loud, but more efficient airflow

This boils down to the 1U server must spin its fans faster that then 2U to move the same amount of air through the server chassis, measured in CFMs (Cubic Feet per Minute).

Additionally, you install a PCIe card in a server that the server itself does not recognize (like Telsa T4 GPUs) , and you may find your fans spinning at full bore, as the server would rather take flight than overheat.

Enter the Dell Fan Susher

Luckily, you can use ipmitools to override a Dell server’s fan speed, and quiet things down a great deal. However, you need to keep your eye on temperatures. For this I created Dell-Server-Fan-Shusher.

Its a python script that monitors system temps (via sensors), and NVIDIA GPU temps (via nvidia-smi – when present), and sets fan speeds accordingly. It currently has seven threshold levels for temp and fan speeds, all of which can easily be modified.

Installation is one command and its scheduled either via cron or systemd.

sudo ./install.sh

The deployed fan_control.py reads system temps in the following order.

Sysfs (/sys/class/hwmon)
sensors
ipmitool sdr list (last fallback)

It also gets GPU temps via nvidia-smi and system temps via IPMI (e.g. Inlet, Exhaust, CPU packages, etc.).

Its Getting Hot in Here

The susher has been working fine for months, but as I mentioned its no longer Winter and the ambient air in my “server room” has been rising. See output from my Netbotz 450 below. Starting to get hotter than a grandparent’s Florida condo.

Line graph showing temperature readings over time from a sensor pod. The y-axis represents temperature in Fahrenheit, ranging from 71 to 77 degrees. The x-axis shows time intervals. The maximum temperature recorded is 75.4 degrees, and the minimum is 72.3 degrees.

So why I am posting all this? So this morning, when I attempted to log into my main hypervisor to start on my 3rd installment of my HPC GPU Cluster journey, I found the host unresponsive and throwing the errors below on the console. Time to reboot.

Terminal screen showing error messages for a network adapter in Red Hat Enterprise Linux, indicating it has stopped due to overheating and suggesting to restart the computer or replace the adapter.

Overheating NIC?

So here is what happened, the ixgbe driver detected that the adapter overheated and disabled it to protect the hardware. When that happens, all ports on that card stop working. In the console, kernel logs are reporting a thermal shutdown of the Intel 10GbE network adapter. Specifically the Intel X540-AT2, which is a dual port 10Gbe copper (RJ45) adapter – with a large heatsink (some variants of this card have a fan.

			
lspci -s 0000:82:00.0
82:00.0 Ethernet controller: Intel Corporation Ethernet Controller 10-Gigabit X540-AT2 (rev 01)

A few minutes after a reboot the error returns, and the NIC goes offline again and is accessible only via the IDRAC console. At this point I cannot keep the system online long enough to do any meaningful troubleshooting. So we need to shush the susher. So from the console we disable it and then reboot again.

			
# systemctl disable --now dell-r730-fan-control.timer
Removed '/etc/systemd/system/timers.target.wants/dell-r730-fan-control.timer'.

From our workstation we connect to the servers IDRAC and set manual fan control and set fan speeds to 100%. We do this while the target system is in the process or rebooting.

			
ipmitool -I lanplus -H 10.1.10.20 -U root -P calvin  raw 0x30 0x30 0x01 0x00
ipmitool -I lanplus -H 10.1.10.20 -U root -P calvin raw 0x30 0x30 0x02 0xff 100

Hopefully now we can keep the system online long enough to see what is really going on, as the server itself is not reporting any temperature issues on the idrac.

Troubleshooting

So first lets check the system logs and see how many times that this has occurred.

grep -r "over heat\|overheat\|stopped because" /var/log/ 2>/dev/null | tail -50

We see two events today, and a 3rd event a few days ago (probably patient zero).

Date	Time	Event
Mar 22, 2026	12:04:56	Both Intel 10GbE NICs (enp130s0f0, enp130s0f1) stopped due to overheat
Mar 22, 2026	13:17:24	Same overheat again shortly before reboot at 13:24:59
Mar 15, 2026	11:39:31	Same overheat on both NICs

Digging into logs a bit further, we see the following at around 12:04

Fan speed: 15% (~3800 RPM)

GPU temp: 35°C
System temps: max 47°C (sensors 24–25 and 39 at 41–47°C)
Action: Fan control had just set fans to 15% for the “LOW” threshold.

Intel X540-AT2 thermal specs

A quick internet search yields the following. This NIC needs to get pretty hot to experience a thermal shutdown

Specification	Value	Notes
Operating temp (ambient)	0°C to 55°C	Marketing spec for 200 LFM airflow
Extended ambient	0°C to 70°C	With 300 LFM airflow and adequate heatsink
Tcase max	107°C	Max case temp at heat spreader (die-level limit)

NIC temperature visibility

So the Intel ixgbe driver does not expose temperature to Linux:

No hwmon temperature sensor under /sys/...
ethtool does not show NIC temperature

So there is no NIC temperature in system logs. The “over heated” message comes from the NIC’s internal thermal protection. The driver only reports the event; the actual NIC temperature is not logged. At this point we do no have a method to pull the temp from the NIC.

Additional, there are no log messages like thermal warnings, throttling, or high-temperature notices before the shutdown. So there is really nothing that we can check for in the logs and use as a trigger for our Dell Fan Controller (Shusher).

Event	Last ixgbe message before overheat	Overheat
Mar 22, 12:04:56	11:58:02 – NIC Link is Up 10 Gbps	12:04:56 – overheat (about 7 minutes later)
Mar 22, 13:17:24	13:11:28 – NIC Link is Up 10 Gbps (after reboot)	13:17:24 – overheat (about 6 minutes later)
Mar 15, 11:39:31	No ixgbe messages in preserved logs before this time	11:39:31 – overheat

Additionally, none of our reported temps from lm-sensors show any temperature issues, and we can see that the fan-susher had recently adjusted fans to 15% due to somewhat amenable temps.

LM-Sensors

Currently sensors detects the following temperatures on this R730.

Chip	Sensor	Current	Limits
coretemp-isa-0000 (CPU Package 0)	Package id 0	28°C	high 83°C, crit 93°C
	Core 0–28 (16 cores)	22–25°C	high 83°C, crit 93°C
coretemp-isa-0001 (CPU Package 1)	Package id 1	29°C	high 83°C, crit 93°C
	Core 0–28 (16 cores)	22–25°C	high 83°C, crit 93°C

Lets run sensors-detect and see if we can add any additional sensors that might help us get a better picture of temps across the system

# sensors-detect

We answer “Yes” at each prompt. Any new modules/sensors are added to /etc/sysconfig/lm_sensors

Now we reload all the sensors

 . /etc/sysconfig/lm_sensors; for m in $HWMON_MODULES $BUS_MODULES; do [ -n "$m" ] && sudo modprobe -r $m 2>/dev/null; done; for m in $BUS_MODULES $HWMON_MODULES; do [ -n "$m" ] && sudo modprobe $m; done

However, no new modules/temps are output by the sensors command, so no additional system temps to feed to the shusher.

So What Now?

At this point we have a few options, besides just cranking down the AC.

We know that our overheat events occurred when system temps were ~47°C with fans at 15%. So, lets start with an overhaul of the susher and increase fan speeds by 10% for each of the 7 temp thresholds as configured in our .env file, and redeploy.

Updated Fan speed levels (7 tiers)

Level	Temp threshold	Fan speed	Trigger
Very-Low	< 20°C	20%	Below LOW
Low	≥ 20°C	25%	GPU LOW / System LOW
Medium-Low	≥ 35°C	35%	MED_LOW
Medium	≥ 50°C	45%	MED
Medium-High	≥ 60°C	60%	MED_HIGH
High	≥ 60°C (system) / 70°C (GPU)	75%	HIGH
Very-High	≥ 75°C	90%	Auto mode → iDRAC

Our minimum fan speed is now 20% instead of 10%, which should improve airflow over the NICs and reduce overheat risk.

Inlet/Exhaust Differential Logging

For the NIC overheat events (Mar 22 12:04, 13:17 and Mar 15 11:39), inlet/exhaust were not logged, so let’s start logging them on each scheduled run of fan_control.py , so if/when something goes wrong, we can see how hot the air was going in and how much it warmed up inside the chassis.

Safety Floor

Additionally lets setup login in fan_control.py if inlet or exhaust gets too high:

Inlet ≥ 40°C → minimum fan speed set to 35%
Exhaust ≥ 50°C → minimum fan speed set to 35%

Even if GPU/CPU temps look fine, we still ramp fans to protect things like the NIC when chassis air is hot.

Next Steps

For now we are going to let things ride. We have adjusted our fan speeds up, and we setup our safety floor.

If we continue to see issues, we may need to take additional action. This r730 is running a number of Virtual machines which I use as “lab infrastructure”, so I want it running 24/7. And while I could just keep jacking up fan speeds, I would rather take a more proactive approach.

Remove heatsink and apply fresh thermal paste. This card is long in the tooth. Could be dried up.
Move to an earlier revision of the Intel X540-AT2 which came with active fans. (Cheap)
Move to a card who’s driver can expose temperatures, like the Broadcom NetXtreme-E (e.g. BCM57416 – not as cheap)

In theory, I like the 3rd option, as it would be nice to be able to pull temperatures from the the NIC, and allow fan_control.py to actually adjust fan speeds intelligently. In practice, however, replacing the NIC is probably overkill unless I run into a dual port actively cooled Intel with both long and short brackets (I like to keep my options open slot-wise). Although I do like getting packages in the mail.

Setting up Chrony/NTP Server with GPS on Ubuntu 22.04

12/29/2025

Introduction

In this post I will cover setting up a ntp/chrony server on Ubuntu 22.04 using a Satellite GPS Receiver. I have also recently published another post on Chrony, which goes a bit more into basic commands. That post can be found here.

Hardware

Linux Host – Nvidia Jetson Orin Nano 4GB
GPS/GNSS – GlobalSat BU-353-W11

Note: the GlobalSat BU-353-W11 does not support 1pps. It’s designed primarily for positioning and navigation, not precision timing. We can use it as our timesource for chrony, with a typical accuracy: ±50–150 ms. Good enough for a lab.

Hardware Detection

After plugging in the USB cable on the GNSS module, check for a new USB device.

# lsusb
Bus 001 Device 004: ID 1546:01a7 U-Blox AG [u-blox 7]

Output from dmegs also shows the device was detected properly

[347055.572498] usb 1-2.4: new full-speed USB device number 4 using tegra-xusb
[347055.768706] cdc_acm 1-2.4:1.0: ttyACM0: USB ACM device
[347055.768784] usbcore: registered new interface driver cdc_acm
[347055.768788] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

In the output above you can see the device was detected ttyACM0. Now we need to confirm how the device was enumerated. As you can see the device is owned by root and the group is dialout

# ls -l /dev/ttyACM*
crw-rw---- 1 root dialout 166, 0 Dec 29 13:40 /dev/ttyACM0

You can run a quick check to confirm that the device is functioning as shown below

# cat /dev/ttyACM0
$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50

$GPTXT,01,01,02,HW  UBX-G70xx   00070000 FF7FFFFFo*69

$GPTXT,01,01,02,ROM CORE 1.00 (59842) Jun 27 2012 17:43:52*59

$GPGGA,201055.00,3356.15827,N,08345.15611,W,2,12,0.80,280.0,M,-31.5,M,,0000*67

-----------truncated----------------

GPSD

To use a GPS/GNSS antenna with chronyd on Linux for time synchronization and location sharing, we will use the gpsd service to manage the GPS hardware and make its data accessible to other applications, including chronyd

Package Installation

# sudo apt update
# sudo apt install gpsd gpsd-clients chrony pps-tools

GPSD Configuration

Identify the GPS device: The device will likely be /dev/ttyUSB0, /dev/ttyACM0, or similar. You can verify this by running cat /dev/ttyUSB0 (replace ttyUSB0 with your suspected device) and looking for NMEA strings (lines starting with $GPGGA, $GNRMC, etc.).

Edit the gpsd configuration file: Open /etc/default/gpsd and set the DEVICES, GPSD_OPTIONS, and USBAUTO variables.

START_DAEMON="true"
GPSD_OPTIONS="-n -b"
DEVICES="/dev/ttyACM0"
USBAUTO="false"
GPSD_SOCKET="/var/run/gpsd.sock"

For reference here are configuration params for GPSD_OPTIONS

Flag	Argument	Meaning	Notes
`-n`	none	Start reading GPS immediately	Required for chrony/NTP
`-b`	none	Read-only mode (no device writes)	Recommended for USB pucks
`-N`	none	Run in foreground	Debug only
`-D`	`<level>`	Debug verbosity	Use `-D 2` or `-D 3`
`-F`	`<path>`	Control socket path	Needed for manual runs
`-s`	`<baud>`	Force serial baud rate	UART devices only
`-S`	`<port>`	TCP listening port	Rare; usually disabled
`-G`	none	Allow remote TCP clients	Avoid on servers
`-l`	none	List drivers and exit	Diagnostic
`-V`	none	Show version and exit	Informational
`-h`	none	Help output	Reference

Enable and start `gpsd`

# sudo systemctl enable gpsd
# sudo systemctl restart gpsd

Verify `gpsd` is receiving data

# cgps -s

Output below

Screen output from a GPSD client showing real-time GPS data, including time, latitude, longitude, altitude, speed, and satellite information.

Interpreting the output from cgps

High-Level Status (The Big Picture)

(Satellites) Seen / Used: 13 / 11
Fix: 3D DGPS FIX – means the receiver has solved all three spatial dimensions: (Latitude, Longitude, Altitude)
Time is valid
Position accuracy: ~5–10 feet horizontal

Satellite Section (Right Pane)

Seen 13 / Used 11

This means:

The receiver can currently see 13 satellites
11 of those are strong enough to be used in the solution

This is quite a healthy signal for a device sitting inside up against a window.

Anything above:

4 used → valid 3D fix
8+ used → very solid geometry
10–12 used → excellent (we are here)

Constellations

GP = GPS
- U.S. GPS constellation
- Medium Earth Orbit (≈20,200 km)
- ~30 active satellites worldwide
SB = SBAS (WAAS corrections)
- Satellite-Based Augmentation System
- Broadcast correction data
- Improve accuracy of GPS measurements
- Do not provide independent position fixes

The presence of SBAS satellites indicates differential reminder data is available, improving accuracy.

Fix & Timing (Left Pane)

Fix State

Status: 3D DGPS FIX (1 secs)

3D = Latitude, longitude, altitude solved
DGPS = WAAS corrections applied
(1 secs) = Fix age (very fresh)

Time Quality

Time: 2025-12-29T20:32:22.000Z
Time offset: 0.078609772 s

Chrony

Install Chrony via apt

# apt install chrony -y

Configure Chrony

Edit /etc/chrony/chrony.conf. This config has been tested on Ubuntu 22.04, YMMV on other Linux versions.

	###############################################################################
	# Chrony configuration
	#
	# Purpose:
	# – Discipline system time using a USB GPS receiver via gpsd (NMEA-only)
	# – No PPS available, so accuracy is milliseconds (not microseconds)
	# – Act as a low-priority NTP server for the local network
	#
	# Notes:
	# – Chrony always operates internally in UTC
	# – GPS time is provided by gpsd over a UNIX socket
	###############################################################################

	#——————————————————————————
	# Include additional configuration snippets
	#——————————————————————————
	# Allows drop-in configuration files (not required, but standard on Ubuntu)
	confdir /etc/chrony/conf.d

	###############################################################################
	# Debug / observability
	###############################################################################

	# Where chrony writes its own detailed log streams
	logdir /var/log/chrony

	# Enable detailed logs:
	# – tracking: disciplined clock state (offset/freq/skew, etc.)
	# – measurements: raw samples from sources (very useful for refclocks)
	# – statistics: aggregate stats per source
	log tracking measurements statistics

	# Log when chrony makes a clock correction bigger than the thresholds
	# (units: seconds). Helps correlate “why did time jump?” events.
	logchange 0.5



	#——————————————————————————
	# GPS reference clock (via gpsd)
	#——————————————————————————
	# Use gpsd's UNIX socket as a reference clock.
	#
	# SOCK /var/run/gpsd.sock
	# – Chrony does NOT talk to the GPS device directly
	# – gpsd parses NMEA and provides time samples
	#
	# refid GPS
	# – Human-readable label shown in chronyc output
	#
	# poll 4
	# – Poll interval = 2^4 seconds = 16 seconds
	#
	# precision 1e-1
	# – Declare expected precision (~100 ms)
	# – REQUIRED for NMEA-only GPS to avoid sample rejection
	#
	# delay 0.2
	# – Account for USB + NMEA sentence latency
	#
	# trust
	# – Explicitly allow chrony to accept this low-precision refclock
	#
	#refclock SOCK /run/gpsd.sock refid GPS poll 4 precision 1e-1 delay 0.2 trust prefer
	refclock SHM 0 refid GPS poll 4 precision 1e-1 delay 0.2 trust prefer



	#——————————————————————————
	# Standalone operation policy
	#——————————————————————————
	# Allow chrony to discipline the system clock even if:
	# – No network NTP servers are configured
	# – GPS is the only available reference
	#
	# Advertise this host as stratum 10 to NTP clients:
	# – Prevents it from being treated as an authoritative time source
	# – Avoids NTP loops
	# – Appropriate for NMEA-only GPS (no PPS)
	#
	local stratum 2


	#——————————————————————————
	# Clock stepping behavior
	#——————————————————————————
	# Allow the system clock to be stepped (jumped) instead of slewed
	# if the offset is larger than 1 second, but ONLY during startup
	# and only for the first 3 updates.
	#
	# This prevents long convergence times on boot while avoiding
	# disruptive time jumps during normal operation.
	#
	makestep 1.0 3


	#——————————————————————————
	# Frequency drift handling
	#——————————————————————————
	# Persist the measured frequency error of the system clock.
	#
	# This allows chrony to:
	# – Start with a good frequency estimate after reboot
	# – Converge faster
	# – Free-run more accurately if all time sources disappear
	#
	driftfile /var/lib/chrony/chrony.drift


	#——————————————————————————
	# NTP server behavior (serving time to clients)
	#——————————————————————————
	# Allow NTP clients from the local subnet to query this server
	#
	allow 10.1.10.0/24

	# Bind NTP service explicitly to this interface/address
	# (prevents listening on unintended interfaces)
	#
	bindaddress 10.1.10.11


	#——————————————————————————
	# Optional dynamic source handling
	#——————————————————————————
	# Allow chrony to use NTP servers provided via DHCP (if present)
	#
	sourcedir /run/chrony-dhcp

	# Allow additional NTP source files to be added modularly
	#
	sourcedir /etc/chrony/sources.d


	#——————————————————————————
	# Security and key material
	#——————————————————————————
	# File containing NTP authentication keys (if used)
	#
	keyfile /etc/chrony/chrony.keys

	# Directory used to store NTS (Network Time Security) cookies and keys
	#
	ntsdumpdir /var/lib/chrony


	#——————————————————————————
	# Logging
	#——————————————————————————
	# Directory where chrony logs are written
	#
	logdir /var/log/chrony

	# Uncomment the following line to enable detailed logging:
	# log tracking measurements statistics


	#——————————————————————————
	# Stability and safety controls
	#——————————————————————————
	# Prevent chrony from applying updates if clock estimates become unstable
	#
	maxupdateskew 100.0

	# Periodically sync the system time back to the hardware RTC
	# (every ~11 minutes)
	#
	rtcsync


	#——————————————————————————
	# Leap second handling
	#——————————————————————————
	# Obtain leap second and TAI-UTC offset information from the system
	# timezone database, operating in strict UTC mode.
	#
	leapsectz right/UTC

view raw gistfile1.txt hosted with ❤ by GitHub

Explanation of Chrony Config for GPSD

Option	Purpose
`SOCK /var/run/gpsd.sock`	Read time from gpsd
`refid GPS`	Label in chrony output
`poll 4`	Poll every 16 seconds
`precision 1e-1`	~100 ms accuracy (realistic for NMEA)
`delay 0.2`	USB + NMEA latency
`makestep 1.0 3`	Allow initial step corrections

Start and Enable

# systemctl enable chrony.service
# systemctl start chrony.service

After a few minutes, we should start to see pre-configured clients appear in the output of the command below

 # chronyc clients
Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
=============================================================================
scar.lab                        5      0   6   -    30       0      0   -     -

Chrony Client-side Setup

Ubuntu Client

$ sudo apt install chrony -y

Configure the to listen to the chrony server address 10.1.10.10. Comment out any other server or pool directives in /etc/chrony/chrony.conf.

server 10.1.10.11

Start and enable the service.

$ sudo systemctl enable chrony --now

Check configured time source for chrony

$ chronyc -n sources -v

What the above output tells you

All NTP servers/pools configured for this client
Which source is currently selected
Reachability and time quality

Key indicators

Symbol	Meaning
`^*`	Current sync source
`^+`	Candidate source
`^-`	Reachable, not selected
`^?`	Unusable / not trusted yet

Cisco Catalyst Client Config

Use the commands below to configure your Cisco switch to use the new timesource

# Enter global configuration mode
configure terminal

# Define the NTP server
ntp server 10.1.10.11

# (Optional) Set the switch to use its own hardware clock if it loses sync
ntp master 10

# Exit and save
end
write memory

HomeLab: Simple DHCP Service Configuration on a Cisco Router

Cisco Homelab Networking

10/15/2013

Sometimes when I learn something new in the world of technology, I am often amazed that something that I assumed was technically advanced is rather quite simple.

Such is the case with configuring DHCP on a Cisco Router. I mean, is it just me or do network guys sometimes act as if everything that they do is takes elite technical skills and tons of experience. Don’t get me wrong, I know that networking is not exactly easy. But can we just agree to admit that once in a while some things are easier done than said. Anyway, for me this was the case with configuring a DHCP pool on a Cisco Router.

In this instance I was working on getting a new virtual machine up and running on my ESXi host. This particular appliance needed to boot via dhcp so you could access its web interface. So I jumped on my 2621xm and created the pool.

First we enable the dhcp service

r-2621-1(config)#service dhcp

Then we create a pool

r-2621-1(config)#ip dhcp pool LabPool
r-2621-1(dhcp-config)#network 10.2.0.1 255.255.255.0

Next we set a few bits and bobbles so that clients can route.

r-2621-1(dhcp-config)#dns-server 10.2.0.71
r-2621-1(dhcp-config)#default-router 10.2.0.1
r-2621-1(dhcp-config)#domain-name localdomain

In this case I wanted to exclude a bunch of ips from the range

r-2621-1(dhcp-config)#ip dhcp excluded-address 10.2.0.1 10.2.0.100

Now save your config with copy run start.

The command below shows me all my dhcp clients

r-2621-1#show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
Hardware address/
User name
10.2.0.101 0050.569a.7dbe Oct 16 2013 11:21 PM Automatic

This handy command shows me information pertaining to my pool

r-2621-1#show ip dhcp pool

Pool LabPool :
Utilization mark (high/low)    : 100 / 0
Subnet size (first/next)       : 0 / 0
Total addresses                : 254
Leased addresses               : 1
Pending event                  : none
1 subnet is currently in the pool :
Current index        IP address range                    Leased addresses
10.2.0.102           10.2.0.1         – 10.2.0.254        1
r-2621-1#show ip dhcp conflict

HomeLab: Upgrading Cisco IOS Via tftp on RHEL

Cisco Networking

08/31/2013

So I was planning on blogging about this process simply because I keep forgetting it. Being that I am in the middle of building out my lab, and have a ton of old cisco hardware with ancient images, I have found myself going through the process of updating firmware quite a bit as I tinker with different IOS images.

The first thing that you are going to need is a tftp server, which I am running on my Fedora 18 desktop. Its a very easy setup, and has been simply documented on the link below. Note the article below is specfically about how to setup a tftp server on RHEL, however the process is pretty much the same.

How to Install a tftp Server on RHEL

Now if you are looking to setup a tftp server on Windows, well I cannot help you there. If I recall you just download and install a server app, and away you go.

Below is another link that I have found that also does a fine job of explaining the Cisco side of the process simply, without getting too technical and long winded.

How to Upgrade Cisco IOS Images

RHEL6 – How to Setup an Anonymous Download Only FTP Server

Redhat

08/30/2012

A while back I spit out a post on how to configure an anonymous ftp server that allowed uploads and downloads, which you can find here.

Its a very exciting read and will tell you everything that you need to know to get you up and running with an anonymous ftp server. However those instructions are specifically for a server that allows anonymous uploads as well as downloads. So today we are going to go over only the steps for anonymous download, which is actually much easier.

Basic Install & Configuration

So first lets install vsftp.

# yum -y install vsftpd && service vsftpd start && chkconfig vsftpd on

Then edit /etc/vsftp/vsftpd.conf and make sure that the following line is uncommented.

anonymous_enable=YES

You should also be aware of the following configuration directive. By setting local enable to no in /etc/vsftp/vsftpd.conf, you disallow local Unix users access to ftp, which ensures that your ftp server is truly anonymous only.

local_enable=no

Now restart vsftpd and you should be in business

Testing Anonymous Download

To test ftp you need an ftp client, which can be installed via yum as seen below.

yum -y install ftp

Then you should be able to ftp to localhost like as seen below and get a file. Note that an anonymous login does not a password

# ftp localhost
Trying 127.0.0.1…
Connected to localhost (127.0.0.1).
220 (vsFTPd 2.2.2)
Name (localhost:root): anonymous
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
227 Entering Passive Mode (127,0,0,1,170,125).
150 Here comes the directory listing.
drwxr-xr-x    2 0        0            4096 Aug 30 15:37 pub
-rw-r–r–    1 0        0               0 Aug 30 15:39 test2
-rw-r–r–    1 0        0               0 Aug 30 15:38 testfile
226 Directory send OK.
ftp> get test2

The same test executed as root ( a local user) should fail as seen below.

# ftp localhost
Trying 127.0.0.1…
Connected to localhost (127.0.0.1).
220 (vsFTPd 2.2.2)
Name (localhost:root): root
530 This FTP server is anonymous only.
Login failed.
ftp>

Unix File Permissions and SELinux

One of the things that can ruin your day when it comes to getting and ftp server up and running is SELinux. However when setting up an anonymous download ftp server using the default ftp root directory you don’t actually need to change anything.

By default your ftp root directory is going to be /var/ftp/, and its SELinux context and default perms are going to be as seen below.

drwxr-xr-x. root root system_u:object_r:public_content_t:s0 /var/ftp

Here the default context is public_content_t which by allows reads but not writes, and the default Unix perms allow reads and not writes.

Changing Default FTP Root Directory

If you wanted to change anonymous vsftp to use a different root directory (other than /var/ftp) you would need to add the following line to /etc/vsftpd/vsftpd.conf. In the example below I am setting my new ftp root to /shared/ftp

anon_root=/shared/ftp

You are also going to need to asign the correct SELinux file context (public_content_t) to your new directory.

# semanage fcontext -a -t public_content_t “/shared/ftp(/.*)?”

# restorecon -vvFR /shared/ftp

Configuration Differences Between Anon Upload and Download

So as I stated above its actually a bit easier to configure an anonymous download only ftp server, than it is to configure it to allow uploads as well. This section for reference only, my post on configuring anonymous upload and download ftp server can be reference here.

First you will need to assign a different SELinux context. Its public_content_rw_t not public_content_t.

# semanage fcontext -a -t public_content_rw_t ‘/var/ftp(/.*)’

# restorecon -vvFR /var/ftp

You will also need to fiddle with SELinux booleans

# setsebool -P allow_ftpd_anon_write=1

And we are also going to want to change the Unix permissions on our ftp root directory. Here we are changing group ownership to ftp and setting the setgid bit.

# chgrp ftp /var/ftp/
# chmod 2760 /var/ftp

Good luck and try not to break anything.

RHEL6 – How To Configure an NFS Server

Linux Redhat

08/31/2011

Do you know whats almost as delicious as a tasty waffle with pure AAA Vermont maple syrup smothered all over it. Neither do I.

However I did run across a very well written blog post on how to configure an NFS server on RHEL6.

Wierd, is it a NFS server or an NFS server, the latter sounds and looks better but i dont think its correct.

Anyway link below:

http://aaronwalrath.wordpress.com/2011/03/18/configure-nfs-server-v3-and-v4-on-scientific-linux-6-and-red-hat-enterprise-linux-rhel-6/

Latest HP Proliant SmartStart and Firmware DVDs 10-06-2010

Hardware Linux

08/06/2010

If you are having issues with your HP server and were thinking about calling support, you might as well put down the phone. Seems to me that their default first step of troubleshooting is to advise you to upgrade to the latest firmware.

According to HP support these were both release just a couple of days ago. Links are below. Firmware DVD is just that, firmware. Smart Start is drivers and diagnostics.

Firmware DVD

Smart Start DVD

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Tag: server

The Homelab Dilemma: Living With Enterprise Servers

Why So Much Noise

Enter the Dell Fan Susher

Its Getting Hot in Here

Overheating NIC?

Troubleshooting

Intel X540-AT2 thermal specs

NIC temperature visibility

LM-Sensors

So What Now?

Updated Fan speed levels (7 tiers)

Inlet/Exhaust Differential Logging

Safety Floor

Next Steps

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Setting up Chrony/NTP Server with GPS on Ubuntu 22.04

Introduction

Hardware

Hardware Detection

GPSD

Package Installation

GPSD Configuration

Enable and start gpsd

Verify gpsd is receiving data

Interpreting the output from cgps

High-Level Status (The Big Picture)

Satellite Section (Right Pane)

Constellations

Fix & Timing (Left Pane)

Fix State

Time Quality

Chrony

Install Chrony via apt

Configure Chrony

Explanation of Chrony Config for GPSD

Start and Enable

Chrony Client-side Setup

What the above output tells you

Key indicators

Cisco Catalyst Client Config

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HomeLab: Simple DHCP Service Configuration on a Cisco Router

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HomeLab: Upgrading Cisco IOS Via tftp on RHEL

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RHEL6 – How to Setup an Anonymous Download Only FTP Server

Basic Install & Configuration

Testing Anonymous Download

Unix File Permissions and SELinux

Changing Default FTP Root Directory

Configuration Differences Between Anon Upload and Download

Like this:

RHEL6 – How To Configure an NFS Server

Like this:

Latest HP Proliant SmartStart and Firmware DVDs 10-06-2010

Like this:

Enable and start `gpsd`

Verify `gpsd` is receiving data