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{{Status
|status=Draft
|owner=Knowledge Agent
|last_update=2026-07-16
|review=Pending
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== Real time each connection tracking (Conntrack) ==
{{TOC}}
In freebsd, session table provides real time rx/tx information for each connection. InLinux netfilter router, connections table only includes information on end of connections by default.


from [[Linux]] kernel version >= 2.6.18, we can use conntract or ''conntrackd'' daemon<ref>https://conntrack-tools.netfilter.org/manual.html</ref>, This tool can be used tosearch, list, inspect and maintain the ''connection tracking'' subsystem of the ''Linux'' kernel.   
== Overview ==
 
Network traffic에 대한 기술 문서입니다.
 
=== Summary ===
 
* 무엇인가? - Network traffic
* 왜 필요한가? - HPC 및 서버 환경에서 필수 개념
* 언제 사용하는가? - 서버 구성, 성능 튜닝, 문제 해결 시
 
 
== Purpose ==
 
이 문서가 존재하는 이유
 
* Goal: Network traffic에 대한 기술 정보 제공
* Scope: Network traffic의 개념, 사용법, 설정
* Non-goals: 다른 주제로의 확장
 
 
== Key Concepts ==
 
{| class="wikitable"
! Concept
! Description
! Related
|-
| Network traffic
| HPC/서버 환경에서 중요한 기술 개념
| [[Linux]], [[Server]]
|}
 
 
== Detailed Explanation ==
 
* [[Network]]
In freebsd, session table provides real time rx/tx information for each connection. In Linux netfilter router, connections table only includes information on end of connections by default.
from [[Linux]] [[kernel]] version >= 2.6.18, we can use conntract or ''conntrackd'' daemon<ref>https://conntrack-tools.netfilter.org/manual.html</ref>, This tool can be used to search, list, inspect and maintain the ''connection tracking'' subsystem of the ''Linux'' kernel.   
[[File:Conntrack points in Netfilter.png|thumb|Conntrack points in Netfilter<ref>https://arthurchiao.art/blog/conntrack-design-and-implementation/#3-implementation-netfilter-conntrack</ref>]]
[[File:Conntrack points in Netfilter.png|thumb|Conntrack points in Netfilter<ref>https://arthurchiao.art/blog/conntrack-design-and-implementation/#3-implementation-netfilter-conntrack</ref>]]
conntrack module traces the connection status of '''<mark>trackable protocols (specific protocols, not all.)</mark>'''   
conntrack module traces the connection status of '''<mark>trackable protocols (specific protocols, not all.)</mark>'''   
=== setup conntrack ===
Set nf_contrack_acct  
Set nf_contrack_acct  
$ sysctl -w net.netfilter.nf_conntrack_acct=1<ref>https://serverfault.com/questions/449250/monitoring-rx-tx-stats-of-current-connections-on-linux</ref>
$ sysctl -w net.netfilter.nf_conntrack_acct=1<ref>https://serverfault.com/questions/449250/monitoring-rx-tx-stats-of-current-connections-on-linux</ref>
Install contrack utility, if you do not have yet
Install contrack utility, if you do not have yet
$sudo apt-get install conntrack  
$sudo apt-get install conntrack  
==== List the existing flows ====
<nowiki>#</nowiki> conntrack -L
<nowiki>#</nowiki> conntrack -L
==== Filter out the listing ====
<nowiki>#</nowiki>conntrack -L -p tcp --dport 22  
<nowiki>#</nowiki>conntrack -L -p tcp --dport 22  
==== Update the ct mark ====
<nowiki>#</nowiki>conntrack -U -p tcp --dport 22 --mark 10
<nowiki>#</nowiki>conntrack -U -p tcp --dport 22 --mark 10
==== delete entries, ====
it can also block TCP traffic when
it can also block TCP traffic when
* stateful rule-set that drops traffic in INVALID state
* stateful rule-set that drops traffic in INVALID state
* ''/proc/sys/net/netfilter/nf_conntrack_tcp_loose'' to zero.
* ''/proc/sys/net/netfilter/nf_conntrack_tcp_loose'' to zero.
* # conntrack -D -p tcp --dport 22
* # conntrack -D -p tcp --dport 22
<nowiki>#</nowiki>conntrack -E
There are bunch of network monitoring tools are available and [https://askubuntu.com/questions/257263/how-to-display-network-traffic-in-the-terminal this discussion] shows most of them
* [https://github.com/raboof/nethogs#readme nethogs] monitors traffic going to/from a machine, per process
* nettop shows packet types, sorts by either size or number of packets.
== Best Practices ==


==== Listen to the connection tracking events ====
* 최신 버전 사용 권장
<nowiki>#</nowiki>conntrack -E
* 공식 문서 참고
* 테스트 환경에서 먼저 검증
 
 
== References ==
 
* [https://wiki.hpcmate.com Network traffic]
 
 
== Related Pages ==
 
* [[Linux]]
* [[Server]]
* [[Hardware]]
* [[Network]]
 
 
[[Category:Network]]
== Knowledge Graph ==


== Network monitoring tools ==
Related
Therer are bunch of tools are available in termal as well<ref>https://askubuntu.com/questions/257263/how-to-display-network-traffic-in-the-terminal</ref>


→ [[Network performance test]]
→ [[RDMA]]
→ [[NIC Bonding]]
→ [[Network]]
→ [[IPMI]]
→ [[SDN]]
→ [[NFS]]


==References==
[[Category:Configuration]]
<references />

Latest revision as of 11:29, 17 July 2026

Template:Status

Template:TOC

Overview

Network traffic에 대한 기술 문서입니다.

Summary

  • 무엇인가? - Network traffic
  • 왜 필요한가? - HPC 및 서버 환경에서 필수 개념
  • 언제 사용하는가? - 서버 구성, 성능 튜닝, 문제 해결 시


Purpose

이 문서가 존재하는 이유

  • Goal: Network traffic에 대한 기술 정보 제공
  • Scope: Network traffic의 개념, 사용법, 설정
  • Non-goals: 다른 주제로의 확장


Key Concepts

Concept Description Related
Network traffic HPC/서버 환경에서 중요한 기술 개념 Linux, Server


Detailed Explanation

In freebsd, session table provides real time rx/tx information for each connection. In Linux netfilter router, connections table only includes information on end of connections by default. from Linux kernel version >= 2.6.18, we can use conntract or conntrackd daemon[1], This tool can be used to search, list, inspect and maintain the connection tracking subsystem of the Linux kernel.

Conntrack points in Netfilter[2]

conntrack module traces the connection status of trackable protocols (specific protocols, not all.) Set nf_contrack_acct $ sysctl -w net.netfilter.nf_conntrack_acct=1[3] Install contrack utility, if you do not have yet $sudo apt-get install conntrack # conntrack -L #conntrack -L -p tcp --dport 22 #conntrack -U -p tcp --dport 22 --mark 10 it can also block TCP traffic when

  • stateful rule-set that drops traffic in INVALID state
  • /proc/sys/net/netfilter/nf_conntrack_tcp_loose to zero.
  • # conntrack -D -p tcp --dport 22

#conntrack -E There are bunch of network monitoring tools are available and this discussion shows most of them

  • nethogs monitors traffic going to/from a machine, per process
  • nettop shows packet types, sorts by either size or number of packets.


Best Practices

  • 최신 버전 사용 권장
  • 공식 문서 참고
  • 테스트 환경에서 먼저 검증


References


Related Pages

Knowledge Graph

Related

→ Network performance test → RDMA → NIC Bonding → Network → IPMI → SDN → NFS

  1. ↑ https://conntrack-tools.netfilter.org/manual.html
  2. ↑ https://arthurchiao.art/blog/conntrack-design-and-implementation/#3-implementation-netfilter-conntrack
  3. ↑ https://serverfault.com/questions/449250/monitoring-rx-tx-stats-of-current-connections-on-linux
Retrieved from "http://wiki.hpcmate.com/index.php?title=Network_traffic&oldid=3403"