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Top Forums UNIX for Advanced & Expert Users Nearly Random, Uncorrelated Server Load Average Spikes Post 303044156 by Neo on Saturday 15th of February 2020 10:14:42 PM
Old 02-15-2020
So, let's try this:

Code:
iptables -A INPUT -s 117.144.138.130/24 -j DROP  #  rogue chinese bot
iptables -A INPUT -s 116.232.49.231/24 -j DROP  #  rogue chinese bot

Empty the "trap" again and block two Chinese subnetworks with rouge, unidentified bot activity.

Honestly, this is starting to "annoy me a lot" in the possibility that these performance hits, and all the time I am spending to find the cause of these hits / spikes, wasting valuable "time in life" is related to rouge, unidentified bots from Chinese networks.

If this continues, I am going to start blocking Chinese networks at the /16 and /8 levels (entire networks).

First, let's see if this is indeed the main source of these spikes. As we all know from situational awareness theory and the famous OODA loop by John Boyd.
  1. OBSERVE
  2. ORIENT
  3. DECIDE
  4. ACT

Already, we have enough information to ACT. But lets continue to OBSERVE Smilie

The loop goes on ... and on ....

Please note that we cannot trust apache2 modules and other third-party software to automatically block IPs, because this can results in blocking the "good bots" which are important for search engine optimization and site traffic.

That means, if this is confirmed that these kinds of bots continue to be the cause of problems, then I will need to DECIDE how to deal with this situation moving forward. I think point in time, I am going to continue to "trap and trace" before making a decision. However, it does seem, at this point, that rouge, unidentified bots from Chinese networks are causing performance issues and need to be "dealt with".

If anyone else has experienced similar issues and has an interesting potential solution to this problem, please reply and share your ideas.

Thanks!

PS: I may consider automating this, as follows:
  1. Capture network session activity when one minute load average exceeds a threshold (as I am doing now).
  2. Filter results captured in the DB based on "hitcount" and "country".
  3. If the "hitcount" exceeds a certain threshold and "country" is in an array of "known to have rouge bots countries".
  4. THEN BLOCK the ip_address/24
 

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timed(8)						      System Manager's Manual							  timed(8)

NAME
timed - The network time daemon SYNOPSIS
timed [-tME] [-n | -i network] FLAGS
Specifies the names of the networks (as defined in the /etc/networks file) to be excluded from clock synchronization. Each network name that is an argument to the -i flag is added to the list of networks that the timed daemon will ignore. If the -i flag is used, timed accesses all networks to which the host is connected except for the specified networks. If neither the -i flag nor the -n flag is used, timed tries to access all the network devices connected to the local host. Do not use the -i and -n flags together. Specifies that a machine can become the time server if the master time server becomes inoperative. See the Restrictions section for more information. Overrides the input of slaves. Use the -E flag in conjunction with the -M flag. It specifies that a master timed system will not average the times of the slaves to calculate the network time. Instead, it distributes the time of its local host as the network time. This flag allows a master timed system to distribute time to a network while the network time is controlled by an outside agent (such as the Network Time Protocol (NTP)). Specifies the names of the networks (as defined in the /etc/networks file) to be included in clock synchronization. When timed is started, it gathers information about all the network devices connected to the local host. The network argument to the -n flag is the name of the network that timed should access. If the -n flag is used, only the specified networks are accessed. If neither the -n flag nor the -i flag is used, timed tries to access all the network devices connected to the local host. Do not use the -n and -i flags together. Enables tracing of messages received in /usr/adm/timed.log. DESCRIPTION
The timed daemon is not invoked at boot time by default. You can use /usr/sbin/timedsetup to configure the timed daemon. The timed daemon synchronizes the host's clock with those of other machines on the local area network that are also running the timed dae- mon. The timed daemon slows the clocks of some machines and speeds up the clocks on other machines to create an average network time. The average network time is computed from measurements of clock differences using the Internet Control Message Protocol ICMP timestamp request message. The service provided by timed is based on a master/slave (client/server) scheme. When timed is started on a machine, it asks the master timed daemon for the network time and sets the host's clock to that time. After that, the host accepts synchronization messages periodi- cally sent by the master and calls the adjtime system call to perform the needed corrections on the host's clock. The timed daemon also communicates with the date command to set the date globally, and with timedc, the timed control program. If the machine running the master ceases to function, a machine that is running the timed daemon with the -M flag becomes the new master timed daemon. Note The timed daemon is provided for compatibility. Tru64 UNIX also provides support for the Network Time Protocol through the xntpd daemon. You should use NTP for time synchronization. If you need to run both NTP and the timed daemon, you must run the timed daemon with the -E flag. If you plan to run both the timed daemon and NTP, you should also configure NTP first. RESTRICTIONS
In configurations with two or more hosts each connected to the same two or more subnetworks, only one of the host can run the timed with the -M option. FILES
Specifies the command path Contains messages traced for the timed command Contains information about the known networks RELATED INFORMATION
Commands: date(1), timedc(8), timedsetup(8) Daemons: xntpd(8) Functions: adjtime(2), gettimeofday(2) delim off timed(8)
All times are GMT -4. The time now is 05:28 AM.
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