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3 billet(s) pour janvier 2026
| Notes rsh rcp | 2026/01/21 18:08 | Jean-Baptiste |
| Git - Duplication d'un dépôt | 2026/01/19 10:22 | Jean-Baptiste |
| Exemple simple de conf Nagios | 2026/01/14 10:07 | Jean-Baptiste |
Réseau Linux pile TCP/IP rto_min scripts
Voir :
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
#! /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
[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
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
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 $8 }' ; done
2024-01-27 11:11:21+01:00 164
2024-01-27 11:11:21+01:00 164
2024-01-27 11:11:22+01:00 165
2024-01-27 11:11:23+01:00 217
2024-01-27 11:11:24+01:00 229
2024-01-27 11:11:24+01:00 151
2024-01-27 11:11:25+01:00 121
2024-01-27 11:11:26+01:00 141
2024-01-27 11:11:27+01:00 118
2024-01-27 11:11:28+01:00 123
Autres
quickack
ip route change default via 10.0.0.1 quickack 1
Réseau Linux pile TCP/IP - TCP retransmission timeout RTO
Params :
Voir :
Round-Trip Time (RTT) also called round-trip delay. RTT is the time required for a signal pulse to travel from a specific source to a specific destination and back again. In this context it is the time it takes for an outgoing TCP client packet to be acknowledged by the server.
Le temps d'aller-retour (RTT) est le temps qu'il faut aux données pour aller et revenir d'un certain point sur un réseau.
RTO pour les connexions sur le port 8080 Client
# Sur le client ss -i -n | egrep -A1 '[0-9]:8080\s+$' |egrep -o 'rto:\w+' # Sur le serveur ss -i -n | egrep -A1 '[0-9]:8080\s+[^$]' |egrep -o 'rto:\w+'
Réseau - port TCP UDP - netcat
Voir :
- Mesures netcat
Voir aussi :
- ttcp
sudo apt-get install ncat
Exemple
nc -n -vvv 192.168.1.1 nc -v -w 3 gnu.org
timeout 3 bash -c "</dev/udp/192.168.1.253/53" && echo "port open" || echo "port closed"
ipv6
nc -6 -lnvvvv 1234
nc -6 2001:bc8:4400:2402::3521 1234
Réseau - nom interface NIC - garder le nommage eth0 - predictable names - biosdevname
Voir :
sudo rgrep -w eth0 /etc udevadm test-builtin net_id /sys/class/net/eth0 2>/dev/null
RedHat
rpm -e biosdevname
boot kernel linux parametres
biosdevname=0 net.ifnames=0
Autre solution
- /etc/udev/rules.d/70-persistent-net.rules
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:20:19:52:d3:be", ATTR{type}=="1", NAME="eth0"
Mettre la véritable @MAC de la carte NAT dans le champ ATTR{address} de la ligne correspondant à eth0 en minuscules
blog.txt · Dernière modification : de 127.0.0.1