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1. NTP Support Web
1.1. Terms and Conditions
1.2. Information for new users
1.3. Other starting points for NTP Solutions
1.4. Useful Links
2. Proxies, Tunnels, and VPNs
2.1. UDP vs. TCP
2.2. Proxies and Tunnels
2.2.1.
ssh
Tunnels
2.3. VPNs
3. Quick Start Guides & Hints
3.1. Getting Started With NTP
3.1.1. What NTP is and what it does
3.1.2. The names of the programs: Is it
ntpd
or
xntpd
?
3.1.3. Pick your servers
3.1.4. "Manually" set the clock correctly just once
3.1.5. Set the clock correctly on every boot up
3.1.6. Keep the clock in sync permanently and continuously.
3.1.7. What about stratum 1, 2, 3 and all that?
3.1.8. Check your work.
3.1.9. Running NTP on many machines in a network.
3.1.10. Further resources
3.2. NTP 4.x for Windows NT
4. Installing NTP
4.1. The NTP Project Reference Implementation Distribution
4.1.1. Installing an ntp.org software release, and Getting Support
4.2. Debian GNU/Linux
4.2.1. NTP Pool Client
4.2.2. Custom Configuration
4.3. FreeBSD
4.4. NetBSD
4.5. OpenBSD
4.6. Microsoft Windows
4.6.1. Using PPS Signals On Windows
4.6.1.1. The Original PPS Support Using A Special Kernel Driver
4.6.1.2. The PPS Hack
4.6.1.3. The PPS API Loopback Provider
4.6.2. Configuring PPS Support
4.6.2.1. Specifying The PPS Provider Via A Registry Key
4.6.2.2. Specifying The PPS Provider Via Environment Variables
5. Designing Your NTP Network
5.1. NTP Access Policy
5.2. Choosing Reference Clocks
5.3. Selecting Offsite NTP Servers
5.3.1. Upstream Time Server Selection Criteria
5.3.1.1. Rules of Engagement
5.3.1.2. Upstream Time Server Proximity
5.3.1.3. Time Source Diversity
5.3.1.4. Network Routing Diversity
5.3.1.5. Communications Methods
5.3.1.6. Security Concerns
5.3.2. Stratum in Time Servers
5.3.3. Upstream Time Server Quantity
5.3.4. Excessive Number of Upstream Time Servers
5.3.5. Local Clock
5.3.6. High Availability
5.3.7. Using
pool.ntp.org
Servers
5.3.7.1. Abuse of
pool.ntp.org
Servers
5.4. Place your reference clocks
5.5. Your core NTP server machines
5.6. Distributing time from your routers
5.7. Distributing time to your machines
6. Configuring NTP
6.1. Configuring Refclocks
6.1.1. Configuring ATOM (PPS) Refclocks
6.1.2. Configuring Bancomm Refclocks
6.1.3. Installing an Endrun Pręcis CT CDMA based refclock.
6.1.4. Configuring Garmin Refclocks
6.1.4.1. General Notes
6.1.4.2. GPS18x-LVC specifics
6.1.4.3. Related Links
6.1.5. Configuring Hopf Refclocks
6.1.6. Configuring HP Z3801A Refclocks
6.1.7. Configuring Irig Refclocks
6.1.8. Configuring Jupiter Refclock with linux
6.1.9. Configuring Local Refclocks
6.1.9.1. Undisciplined Local Clock
6.1.9.2. Orphan Mode
6.1.10. Configuring Modem Refclocks
6.1.11. Configuring Motorola ONCORE Refclocks
6.1.12. Configuring NMEA Refclocks
6.1.12.1. Accord NAV2300 GPS Clock
6.1.12.2. Garmin GPS18x LVC
6.1.12.3. Sure Electronics GPS evaluation board
6.1.12.4. µBLOX NEO-M8T
6.1.12.5.
ntpd
NMEA refclock driver update
6.1.13. !! Configuring Parse Refclocks
6.1.14. Configuring PPS With PARSE Refclocks
6.1.14.1. The equipment
6.1.14.2. Building the kernel support
6.1.14.3. Building NTP
6.1.14.4. Configuring NTP
6.1.15. Configuring PST Traconex Refclocks
6.1.16. Configuring Trimble Palisade/Acutime Refclocks
6.1.16.1. Getting it working:
6.1.16.2. Making the clock more accurate
6.1.16.2.1. Min / Max Poll Values
6.1.16.2.2. APIC support in Linux 2.6.x Kernels
6.1.16.2.3. ACPI
6.1.16.2.4. Results
6.1.16.3. How did I get and graph the data?
6.1.17. Configuring TrueTime Refclocks
6.1.18. Configuring u-blox Antaris Refclock
6.1.19. Configuring WWV Refclocks
6.1.20. Configuring WWVB Refclocks
6.2. Orphan mode
6.2.1. Configuration
6.3. Configuring Multicast Servers
6.4. Configuring Multicast Clients
6.5. ntpd access restrictions
6.5.1. Configuring your ntpd restrictions
6.5.1.1. Choose the right default restriction
6.5.1.1.1. NAT or Firewall?
6.5.1.1.2. Blocking Unauthorized Access
6.5.1.1.3. Allow Queries?
6.5.1.1.4. Local Network Threat Level
6.5.1.2. Add exceptions for specific hosts/subnets
6.5.1.2.1. If you used 'restrict default ignore'
6.5.1.2.2. Other default restrictions
6.5.2. Access Control Options
6.5.3. Important Notes
6.5.3.1.
notrust
changed between versions 4.1 and 4.2
6.5.3.2. Nessus identification and
ntpd
6.5.3.3. DRDoS / Amplification Attack using ntpdc monlist command in NTP < 4.2.7p26
6.6. Adding NTP Server Variables
6.7. Autokey Configuration for NTP stable releases
6.7.1. How To Use This Guide
6.7.2. Server Set-Up
6.7.2.1. Create the NTP Keys directory
6.7.2.2. Edit ntp.conf
6.7.2.2.1. Broadcast and Multicast Autokey
6.7.2.3. Generate Server Parameters
6.7.2.3.1. IFF Parameters
6.7.2.4. Restart ntpd
6.7.2.5. Server Parameter Update
6.7.3. Client Set-Up
6.7.3.1. Create the NTP Keys directory
6.7.3.2. Edit ntp.conf
6.7.3.2.1. Unicast Autokey
6.7.3.3. Generate Client Parameters
6.7.3.4. Install Group/Client Keys
6.7.3.4.1. IFF Group Keys
6.7.3.5. Restart ntpd
6.7.3.6. Client Parameter Update
6.7.4. Monitoring Authentication Status
6.7.4.1. Crypto Association Flags
6.7.5. Related Links
6.8. Autokey Configuration for NTP 4.2.4 (and earlier)
6.8.1. How To Use This Guide
6.8.2. Server Set-Up
6.8.2.1. Create the NTP Keys directory
6.8.2.2. Edit ntp.conf
6.8.2.2.1. Broadcast and Multicast Autokey
6.8.2.3. Generate Server Parameters
6.8.2.3.1. IFF Parameters
6.8.2.3.2. GQ Parameters
6.8.2.3.3. MV Parameters
6.8.2.3.4. Multiple Identity Schemes
6.8.2.4. Restart ntpd
6.8.2.5. Server Parameter Update
6.8.3. Client Set-Up
6.8.3.1. Create the NTP Keys directory
6.8.3.2. Edit ntp.conf
6.8.3.2.1. Unicast Autokey
6.8.3.3. Generate Client Parameters
6.8.3.4. Install Group/Client Keys
6.8.3.4.1. IFF Group Keys
6.8.3.4.2. GQ Group Keys
6.8.3.4.3. MV Client Keys
6.8.3.5. Restart ntpd
6.8.3.6. Client Parameter Update
6.8.4. Monitoring Authentication Status
6.8.4.1. Crypto Association Flags
6.8.5. Related Links
6.9. Locking ntpd in memory
6.10. Simple Client Configuration
6.10.1. 4.2.7 and Later Simple Client Configuration, Visible on the Internet
6.10.2. 4.2.6 and Later Simple Client Configuration, Visible on the Internet
6.11. Important Notes
6.12. DHCP Auto-configuration
6.12.1. ISC dhcp 3
6.13. How dynamic IP addresses affect ntpd
6.14. Using the NIST Leap Second File
6.14.1. NTP Versions 4.2.6 and newer
6.14.2. NTP Versions before 4.2.6
6.15. NTP over cellular - a brief study
6.15.1. Background
6.15.2. Environment
6.15.3. Configuration
6.15.4. Disclaimer
6.16. Third-party HOWTOs and guides
7. Starting NTP
7.1. Starting NTP 4
7.1.1. Start
ntpd
as Early as Possible
7.1.2. Avoid DNS Delays
7.1.2.1. Use IP Addresses or
/etc/hosts
Entries
7.1.2.2. Use Good Local Resolvers
7.1.3. Wait Before Starting Time-sensitive Services
7.1.4. Configuration file tips
7.1.4.1. Use
iburst
for Faster Sync
7.1.4.2. Avoid Using _Burst_
7.1.4.3. Increase Number of Time Servers for Time-sensitive Systems
7.1.4.3.1. Number of Time Server "Candidates" and "Sane"
7.1.4.3.2. Number of Time Servers Specified in =/etc/ntp.conf=
7.1.4.4. Sensitivity to Boot-time Delays
7.2. How is NTP started?
7.3. When should NTP be started?
8. Monitoring and Controlling NTP
8.1. REFID Format
8.1.1. References
8.1.2. Example Code for Generating IPv6 Refids.
9. Troubleshooting NTP
9.1. Known Hardware Issues
9.1.1. APIC and ACPI
9.1.2. Variable Speed Processors
9.1.3. Dell Inspiron 8100
9.1.4. Sun Fire V100, Netra X1, etc.
9.1.5. Disable your FIFO for lower jitter with serially-attached refclocks
9.1.5.1. Disabling your FIFO under Linux
9.1.5.2. Disabling your FIFO under FreeBSD 5.x/6.x
9.1.5.3. Disabling your FIFO under older versions of FreeBSD
9.1.6. Mac Mini (and other machines having poor
TICK
settings)
9.1.7. nForce2 motherboards: HAL issues and FSB Spread Spectrum
9.1.8. PPS signals via RS-232 serial port
9.2. Known Operating System Issues
9.2.1. Lost Interrupts
9.2.1.1. Scheduler HZ too high
9.2.1.2. Disk drivers using non-DMA
9.2.2. Xen, VMware, and Other Virtual Machine Implementations
9.2.2.1. VMware
9.2.2.2. Xen
9.2.2.3. Final notes
9.2.3. Windows and Sun's Java Virtual Machine
9.2.4. Linux
9.2.4.1. Kernel 2.4 (and Earlier)
9.2.4.1.1. Using a Local Refclock
9.2.4.1.2. Without a Local Refclock
9.2.4.2. Kernel 2.6
9.2.4.2.1. Using a Local Refclock
9.2.4.2.2. Without a Local Refclock
9.2.4.2.3. Lost ticks causing clock instability
9.2.4.2.4. A problem with the Reiser file system
9.2.4.2.5. Running ntpd without root privileges
9.2.4.2.5.1. A problem with IPv6 interfaces after chroot
9.2.4.2.5.2. Using rsyslog in chroot
9.2.4.2.5.3. Name resolution failures in chroot with getaddrinfo()
9.2.4.2.6. Using udev
9.2.4.2.7. Kernel 2.6 Mis-Detecting CPU TSC Frequency
9.2.4.3. Access control mechanisms causing
"permission denied"
errors
9.2.4.3.1. AppArmor
9.2.4.3.2. SELinux
9.2.5. Mac OS X
9.2.6. Sun
9.2.6.1. Sun Device Drivers
9.2.6.1.1. su Driver An issue with the Sun
su
driver has surfaced with respect to PPS support. Currently (200508) the su driver is not supporting PPS correctly in some configurations. Sun is working on a patch for that issue. For more information please refer to
9.3. Daylight Saving Time
9.4. Checking
ntpd
's status
9.5. On-line Troubleshooting Utilities
9.6. Check the
syslog
output
9.7. Problems with
RESTRICT
lines
9.7.1. Problems with _RESTRICT NOTRUST_
9.8. Check the NTP port
9.9. ntp.conf and dhcp
9.10. synchronizing ntp with a server running w32time
10. Testing NTP's Behavior
10.1.
11. Kernel configuration for NTP
12. Development Notes
12.1. NTP-Related RFCs
12.2. NTP-related definitions
13. Other Implementations Of NTP
13.1. Cisco NTP
13.2. Chrony
13.3. Java SNTP Client
13.4. OpenNTPD
13.5. Windows Time Service
13.6. VMware and NTP
13.6.1. General Notes
13.6.2. Configuration Examples
13.6.2.1. ESX Server 3.0.3
14. Refclock Users
14.1. ATOM (PPS) Refclock Users
14.2. Bancomm Refclock Users
14.3. Users of the "Dumb" Refclock
14.4. Endrun Praecis Refclock Users
14.5. Garmin Refclock Users
14.6. HOPF Refclock Users
14.7. HP Z3801A Refclock Users
14.8. Irig Refclock Users
14.9. Jupiter Refclock Users
14.10. Modem Refclock Users
14.11. Motorola Oncore Refclock Users
14.12. NMEA Refclock Users
14.13. Parse Refclock Users
14.14. PST/Traconex Refclock Users
14.15. Trimble Palisade Acutime Refclock Users
14.16. TrueTime Refclock Users
14.17. u-blox Antaris Refclock Users
14.18. WWV Refclock Users
14.19. WWVB Refclock Users
15. Time Scales
16. NTP-related definitions
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Topic revision: r4 - 2003-10-07 - 17:19:00 -
SteveKostecke
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