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When a program runs on multiple servers, the clock on these servers is sometimes the same. However, when the server runs for a certain period of time, the clock on each server may be different, in this case, all servers need to automatically calibrate their respective clocks. NTP is a convenient clock service, which ca
does not have other services related to foreign IP addresses, which is suspicious. I tried to stop the NTP service first, and the network adapter outgoing traffic immediately dropped to a normal level. The problem is found. The cause is unknown. I tried to ask other people and found that there are many attacks recently, collectively referred to as "NTP reflection amplification attack". Its principle is: 1.
: 0.003906 (SEC)Auth delay: 0.000122 (SEC)System flags: bclient PLL monitor filegenSystem uptime: 578 (SEC)Clock stability: 1988.000000 (SEC)Clock frequency: 15904.000000 (SEC)Peer: 120.4.8.1Flags: (configured) (sys peer)Stratum: 11, version: 3Our mode: client, his mode: ServerSubsystem group PID statusXntpd TCPIP 6029448 active You can use the ntpdate clock source ip command to synchronize the clock in real time This article is from the "morning song muniu" blog, please be sure to kee
Linux NTP server-side configuration:1) Setting the/etc/ntp.conf configuration file[Email protected] etc]# vi/etc/ntp.conf# For more information on this file, see the "the Man pages"# ntp.conf (5), NTP_ACC (5), Ntp_auth (5), Ntp_clock (5), Ntp_misc (5), Ntp_mon (5).Driftfile/var/lib/ntp/drift# Permit time synchronization with We time source, but does not# permit the source to a query or modify the service on
Ntp:network Time Protocol is a protocol used to synchronize the timing of a computer, which allows the computer to synchronize its server or clock source (such as a quartz clock, GPS, and so on) to provide a high-precision time correction (less than 1 milliseconds between the LAN and the standard difference, Dozens of MS on the WAN), and can be referred to as a cryptographic acknowledgment to prevent malicious protocol attacks.1. Installation:Yum Install Ntpyum Install TzdataThe
/ntp.confRestrict 127.0.0.1Restrict-6:: 1Restrict 192.168.1.0 mask 255.255.255.0 # allow access to 192.168.1.0 network segmentsServer 127.127.1.0 # Local Clock addressFudge 127.127.1.0 Stratum Local 127.127.1.0 is 10th floor6. Restart ntpd Service[Email protected] ~]#/etc/init.d/ntpd restartClose ntpd: [Failed]Starting ntpd: [OK]7. Test:Before testing, to detect whether the firewall, SELinux are off!!! Service side:[[Email protected] ~]# Date . May 24 Tuesday 15:54:55 CST[email protecte
" now we know how to set the system and hardware time. but the question is, what should I do if neither of these two times is accurate? Then we need to find a server on the Internet that can provide our accurate time and then synchronize our system time through a protocol. Then this protocol is NTP. note that next we will talk about synchronization between the system time and the network server. 4. Prepare for NTP
Directory 1. NTP Introduction 2. NTP protocol Format 3. Relationship between NTP reflect reflection vulnerability and NTP protocol 4. Prerequisites for vulnerability triggering and steps required for attack 5. Reflection on attack and defense against the vulnerability 1. NTP
: driftfile file name Purpose: record the time spent in contacting the upper-level time server in the file specified after the driftfile parameter. Note: driftfile must be followed by a complete file path, not a link file, and must have the permissions that the ntpd daemon can write. Default Configuration items: driftfile/var/lib/ntp/drift Note: I have not changed the driftfile parameter in actual operations. 2) restrict parameter: Permission control
, but do not # Permit the source to query or modify the service on this system. Restrict default kod nomodify notrap nopeer noquery Restrict-6 default kod nomodify notrap nopeer noquery # Permit all access over the loopback interface. This cocould # Be tightened as well, but to do so wocould effect some # The administrative functions. Restrict 127.0.0.1 Restrict-6: 1 # Hosts on local network are less restricted. # Restrict 192.168.1.0 mask limit 255.0 nomodify notrap # Use public
server configurations, and notrap rejects special ntpdq to capture messages, noquery rejects btodq/ntpdc queries (the query here is the server's own status query ). Restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap This is manually added, meaning that all servers from 192.168.1.1-192.168.1.254 can use our NTP server to synchronize time. Server 192.168.146.225 This statement is also manually added, in
255.255.255.0 nomodify notrapRestrict 192.168.30.0 mask 255.255.255.0 nomodify notrap #增加这一行, which IP addresses can be synchronized to the NTP server, or not configured, all network segments by default# Use public servers from the Pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).Server 0.centos.pool.ntp.org IburstServer 1.centos.pool.ntp.org IburstServer 2.centos
adjust time allocation at the speed of light in a large and complex Internet. It uses a design scheme that can return time. It features that the time server is a distributed subnet that can perform self-organized operations and hierarchical management configuration, the logical clock is synchronized to the National Standard Time in wired or wireless mode. In addition, the server can re-allocate the standard time by selecting the algorithm and the time background program through the local route.
Internet that can provide us with accurate time and then synchronize our system time with a protocol, then this Protocol is NTP. Note that all we have to say about synchronization is the synchronization between the system time and the network server.4. Preparation before setting up NTP serverIn fact this title should be changed to set "NTP Relay Server" before t
Linux time synchronization ntp service installation and configuration, linux time synchronization ntp service When we need to manage the time of multiple servers, it is too troublesome to modify one server. The NTP service can solve this problem for us! 1. First install NTP
synchronization is the synchronization between the system time and the network server. 4. Before setting up NTP serverIn fact, the title should be changed to set the "NTP Relay Server" before the preparation is more appropriate. Because no matter how well our computer is configured to run for a long time, it will cause errors, so it is not enough to do NTP serve
Configure NTP, synchronize server time, and configure ntp synchronization server Configure NTP and synchronize server time There are more and more servers in the project. Recently, Database Synchronization has been performed on several servers. When a synchronization error o
0x00 background Two days ago, the heartbleed fat man published an article about NTP-based reflection and amplification attacks. I wrote another article related to NTP because I didn't mention some of the above, or I didn't make it clear enough. You are welcome to leave a comment and I will try again for improvement. Glossary: Ntp server: the
NTP 'ntp _ io. c' authentication Security Restriction Bypass Vulnerability Release date:Updated on: Affected Systems:NTP NTPd Description:Bugtraq id: 72584CVE (CAN) ID: CVE-2014-9298 Network Time Protocol (NTP) is a Protocol used to synchronize computer Time. It can synchronize computers with their servers or clock sou
Final parameters: # Cat/etc/ntp. conf "awk '{if ($0 !~ /^ $/ $0 !~ /^ #/) {Print $0 }}' Or # Cat/etc/ntp. conf | grep "^ [^ #]" Driftfile/var/lib/ntp/driftrestrict default kod nomodify notrap nopeer noqueryrestrict-6 default kod nomodify notrap nopeer noqueryrestrict 127.0.0.1 restrict-6: 1 restrict 192.168.0.0 mask 255.255.0.0 nomodifyserver
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