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{{tag>Brouillon Réseau Linux Kernel TCP RedHat SystemD Service Script Bash CA}}

# Réseau Linux pile TCP/IP rto_min scripts

Voir :
* [[Réseau Linux pile TCP/IP - TCP retransmission timeout RTO]]
* [[reseau_linux_pile_tcp_ip]]


Le hack ci-dessous ne semble plus utile pour RedHat 9.

“NetworkManager now supports advmss, rto_min, and quickack route attributes”
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html-single/9.1_release_notes/index


`network_tcp_tune_change_mto_min.sh`
~~~bash
#! /bin/bash

set -euo pipefail

declare -i ALREADY_SET

# check if file exist
file_exist() {
	[ -e "$1" ]
}

LINE="$(ip route show default | grep ^default)"

if echo "$LINE" | grep -q -e rto_min; then
	ALREADY_SET=1
else
	ALREADY_SET=0
fi

usage() {
	cat <<EOF
SysV init script.
Args are : status, stop, start, restart

EOF
}

status() {
	if [ $ALREADY_SET -eq 1 ]; then
		echo Started
	else
		echo Stopped
	fi
	ip route show default | grep -e '^default'
	echo
	echo "/proc/sys/net/ipv4/tcp_thin_dupack"
	file_exist /proc/sys/net/ipv4/tcp_thin_dupack && cat /proc/sys/net/ipv4/tcp_thin_dupack
	echo
	echo "/proc/sys/net/ipv4/tcp_thin_linear_timeouts"
	cat /proc/sys/net/ipv4/tcp_thin_linear_timeouts
}

start() {
	echo "Starting..."
	file_exist /proc/sys/net/ipv4/tcp_thin_dupack && echo 1 > /proc/sys/net/ipv4/tcp_thin_dupack
	echo 1 > /proc/sys/net/ipv4/tcp_thin_linear_timeouts
	if [ $ALREADY_SET -eq 0 ]; then
		NEW_LINE="$LINE rto_min 8ms"
		echo "ip route change $NEW_LINE"
		echo "$NEW_LINE" | xargs ip route change 
	else
		echo "Already started"
	fi
}

stop() {
	echo "Stopping..."
	if [ $ALREADY_SET -eq 1 ]; then
		NEW_LINE="$(echo "$LINE" | sed -e 's/ lock / /g' -e 's/rto_min [[:alnum:]]\+//')"
		echo "ip route change $NEW_LINE"
		echo "$NEW_LINE" | xargs ip route change 
	else
		echo "Already stopped"
	fi
}

case "${1:-}" in
start)
	start
	;;
restart)
	start
	;;
stop)
	stop
	;;
status)
	status
	;;
-h | --help)
	usage
	;;
*)
	usage
	exit 1
	;;
esac

echo .
~~~


`network_tcp_tune_change_mto_min.service`
~~~ini
[Unit]
Description=Network setting on default gateway. Change rto_min to 8ms. Don not alwaays wait 200ms to resend packet
Wants=network.target network-online.target
After=network.target network-online.target

[Service]
Type=oneshot
# ExecStartPre=/usr/bin/sleep 5
ExecStart=/bin/bash /root/scripts/network_tcp_tune_change_mto_min.sh start
ExecStop=/bin/bash /root/scripts/network_tcp_tune_change_mto_min.sh stop
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target
~~~


## Mesures

### rsync

~~~
truncate -s 1G big_file.img
~~~


#### Avant

~~~
$ rsync --compress-level=0 --progress --human-readable -v --log-file=rsync.log big_file.img target:big_file.img | grep MB
          1.07G 100%   76.63MB/s    0:00:13 (xfr#1, to-chk=0/1)
          1.07G 100%   64.51MB/s    0:00:15 (xfr#1, to-chk=0/1)
          1.07G 100%   69.04MB/s    0:00:14 (xfr#1, to-chk=0/1)
          1.07G 100%   45.00MB/s    0:00:22 (xfr#1, to-chk=0/1)
          1.07G 100%   44.32MB/s    0:00:23 (xfr#1, to-chk=0/1)
          1.07G 100%  129.67MB/s    0:00:07 (xfr#1, to-chk=0/1)
          1.07G 100%   44.98MB/s    0:00:22 (xfr#1, to-chk=0/1)
~~~


#### Après

~~~
$ rsync --compress-level=0 --progress --human-readable -v --log-file=rsync.log big_file.img target:big_file.img | grep MB
          1.07G 100%  110.12MB/s    0:00:09 (xfr#1, to-chk=0/1)
          1.07G 100%  137.35MB/s    0:00:07 (xfr#1, to-chk=0/1)
          1.07G 100%   98.45MB/s    0:00:10 (xfr#1, to-chk=0/1)
          1.07G 100%  129.62MB/s    0:00:07 (xfr#1, to-chk=0/1)
          1.07G 100%  110.69MB/s    0:00:09 (xfr#1, to-chk=0/1)
          1.07G 100%  152.42MB/s    0:00:06 (xfr#1, to-chk=0/1)
          1.07G 100%  110.20MB/s    0:00:09 (xfr#1, to-chk=0/1)
          1.07G 100%  135.79MB/s    0:00:07 (xfr#1, to-chk=0/1)
~~~


### Iperf

Serveur
~~~bash
iperf3 -s -p 8080
~~~


#### Avant



~~~
$ iperf3 -i 1 -P 1 -t 600 -p 8080 -c 192.168.10.10
Connecting to host 192.168.10.10, port 8080
[  4] local 192.168.10.11 port 43100 connected to 192.168.10.10 port 8080
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec  69.0 MBytes   579 Mbits/sec   19    836 KBytes
[  4]   1.00-2.00   sec  23.8 MBytes   199 Mbits/sec  633    652 KBytes
[  4]   2.00-3.00   sec  68.8 MBytes   577 Mbits/sec  894    724 KBytes
[  4]   3.00-4.00   sec  53.8 MBytes   451 Mbits/sec  1251    731 KBytes
[  4]   4.00-5.00   sec  72.5 MBytes   608 Mbits/sec  455    680 KBytes
[  4]   5.00-6.00   sec   158 MBytes  1.32 Gbits/sec   95    921 KBytes
[  4]   6.00-7.00   sec   124 MBytes  1.04 Gbits/sec   25   1.07 MBytes
[  4]   7.00-8.00   sec  57.5 MBytes   483 Mbits/sec  1063   1.27 MBytes
[  4]   8.00-9.00   sec  60.0 MBytes   503 Mbits/sec  761   1.24 MBytes
[  4]   9.00-10.00  sec  63.8 MBytes   535 Mbits/sec  2013   1.18 MBytes
[  4]  10.00-11.00  sec   124 MBytes  1.04 Gbits/sec   33   2.02 MBytes
~~~



#### Après

~~~
$ iperf3 -i 1 -P 1 -t 600 -p 8080 -c 192.168.10.10
Connecting to host 192.168.10.10, port 8080
[  4] local 192.168.10.11 port 43348 connected to 192.168.10.10 port 8080
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec   142 MBytes  1.19 Gbits/sec  612   1.11 MBytes
[  4]   1.00-2.00   sec   232 MBytes  1.95 Gbits/sec   26   1.51 MBytes
[  4]   2.00-3.00   sec   220 MBytes  1.85 Gbits/sec  2551   1.29 MBytes
[  4]   3.00-4.00   sec   139 MBytes  1.16 Gbits/sec  1769    459 KBytes
[  4]   4.00-5.00   sec   130 MBytes  1.09 Gbits/sec  1301    451 KBytes
[  4]   5.00-6.00   sec   125 MBytes  1.05 Gbits/sec  1541    396 KBytes
[  4]   6.00-7.00   sec   126 MBytes  1.06 Gbits/sec  751    448 KBytes
[  4]   7.00-8.00   sec   118 MBytes   986 Mbits/sec  1071    535 KBytes
[  4]   8.00-9.00   sec   124 MBytes  1.04 Gbits/sec  1162    518 KBytes
~~~


### Netcat

Serveur
~~~bash
nc -p 8080 -lk > /dev/null
~~~


#### Avant

~~~
$ while sleep 0.2 ; do echo -n -e "$(date --rfc-3339=seconds)\t" ; (dd if=/dev/zero bs=100000k count=1 | nc 192.168.10.10 8080) 2>&1 | awk '/copied/ { print $8 }' ; done
2024-01-27 11:10:31+01:00       149
2024-01-27 11:10:32+01:00       57.1
2024-01-27 11:10:34+01:00       25.6
2024-01-27 11:10:38+01:00       64.5
2024-01-27 11:10:40+01:00       62.8
2024-01-27 11:10:42+01:00       115
2024-01-27 11:10:43+01:00       215
2024-01-27 11:10:44+01:00       134
2024-01-27 11:10:45+01:00       89.8
2024-01-27 11:10:46+01:00       30.8
2024-01-27 11:10:50+01:00       58.7
~~~


#### Après

~~~
$ while sleep 0.2 ; do echo -n -e "$(date --rfc-3339=seconds)\t" ; (dd if=/dev/zero bs=100000k count=1 | nc 192.168.10.10 8080) 2>&1 | awk '/copied/ { print $8 }' ; done
2024-01-27 11:11:21+01:00       164
2024-01-27 11:11:21+01:00       164
2024-01-27 11:11:22+01:00       165
2024-01-27 11:11:23+01:00       217
2024-01-27 11:11:24+01:00       229
2024-01-27 11:11:24+01:00       151
2024-01-27 11:11:25+01:00       121
2024-01-27 11:11:26+01:00       141
2024-01-27 11:11:27+01:00       118
2024-01-27 11:11:28+01:00       123
~~~


## Autres

### quickack

~~~bash
ip route change default via 10.0.0.1 quickack 1
~~~