Watchdog timer for 4G-modem on CentOS 7
This article is a supplement to my previous post about setting up a home router / file server. Here we will talk about the problem of automatic reconnection to the Internet when a 4G modem hangs. I do not pretend to the originality of the idea, I just want to share my decision with the readers.
In the process of constant work, about once a month, it happened that the USB modem was hanging. This gave me a certain inconvenience: the inability to remotely get on the home computer, to pre-load movies. It was impossible to eliminate this problem remotely; only a modem reboot by power helped. The only way out was to write a script that at a certain time checks the availability of a node on the Internet and, if necessary, reloads the modem.
I found several implementations on the Internet, but not one of them worked normally for me. Therefore, I decided to write my watchdog timer with preference and young ladies . The script was taken from this topic. Rewritten, as far as my qualification allows me, and added new features such as external options.
The script is located in / usr / local / bin /.
To start the script automatically, every five minutes, add the task to cron.
This is the output of dmesg, it shows a modem reset during the execution of the script.
I’ll say right away that the script is very far from ideal, so I’m happy to accept advice and valid criticism.
Separately, I want to thank the user with Toster.ru under the nickname @AlekseyNemiro , for their help in optimizing the script.
UPD 01.22.16 Completed the script with the command to add the path to the PATH variable.
In the process of constant work, about once a month, it happened that the USB modem was hanging. This gave me a certain inconvenience: the inability to remotely get on the home computer, to pre-load movies. It was impossible to eliminate this problem remotely; only a modem reboot by power helped. The only way out was to write a script that at a certain time checks the availability of a node on the Internet and, if necessary, reloads the modem.
I found several implementations on the Internet, but not one of them worked normally for me. Therefore, I decided to write my watchdog timer with preference and young ladies . The script was taken from this topic. Rewritten, as far as my qualification allows me, and added new features such as external options.
Installing and configuring a USB 4G modem in CentOS 7.
First you need to download the missing packages.
Connect the modem and see how it is defined in the system.
Next, you need to configure the interface 4G modem.
We create scripts to activate and deactivate the Internet when the interface is turned on or off.
Here ttyUSB0 is the modem port.
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We raise the interface and check the connection.
yum install usb_modeswitch usb_modeswitch-data Connect the modem and see how it is defined in the system.
dmesg ip a Next, you need to configure the interface 4G modem.
vim /etc/sysconfig/network-scripts/ifcfg-wwp6s0u1i1 DEVICE="wwp6s0u1i1" NAME="wwp6s0u1i1" TYPE="Ethernet" ONBOOT="yes" BOOTPROTO="dhcp" HWADDR="XX:XX:XX:XX:XX:XX" NM_CONTROLLED="no" DNS1=127.0.0.1 DNS2=127.0.0.1 DNS3=127.0.0.1 NOZEROCONF="yes" IPV4_FAILURE_FATAL="no" IPV6INIT="no" ZONE="external" We create scripts to activate and deactivate the Internet when the interface is turned on or off.
vim /sbin/ifup-pre-local #!/bin/bash # PREUP="/etc/sysconfig/network-scripts/pre-up-${1:6}" if [ -x $PREUP ]; then exec $PREUP fi vim /sbin/ifdown-pre-local #!/bin/bash # PREDOWN="/etc/sysconfig/network-scripts/pre-down-$1" if [ -x $PREDOWN ]; then exec $PREDOWN fi vim /etc/sysconfig/network-scripts/pre-up-wwp6s0u1i1 #!/bin/bash # echo -en 'AT^NDISDUP=1,1,"internet.yota"\r\n' > /dev/ttyUSB0 vim /etc/sysconfig/network-scripts/pre-down-wwp6s0u1i1 #!/bin/bash # echo -en 'AT^NDISDUP=1,0,"internet.yota"\r\n' > /dev/ttyUSB0 Here ttyUSB0 is the modem port.
')
We raise the interface and check the connection.
ifup wwp6s0u1i1 ip a The script itself
#!/bin/bash export PATH="$PATH:/usr/sbin" SN="$(basename "$0")" function print_help() { printf "\n" printf ": %s options...\n" "$SN" printf ":\n" printf " -s .\n" printf " -i .\n" printf " -d lsusb -t.\n" printf " -n .\n" printf " -m , lsusb.\n" printf " -h .\n" printf "\n" } # , . if [[ $# = 0 ]]; then print_help && exit 1 fi while getopts ":s:i:d:n:m:h" opt ; do case $opt in s) SITE=$OPTARG; ;; i) IF=$OPTARG; ;; d) DEV=$OPTARG; ;; n) EP=$OPTARG; ;; m) MM=$OPTARG; ;; h) print_help exit 1 ;; *) printf " \n"; printf " %s -h\n" "$SN"; exit 1 ;; esac done if [[ "$SITE" == "" ]] || [[ "$IF" == "" ]] || [[ "$DEV" == "" ]] || [[ "$EP" == "" ]] || [[ "$MM" == "" ]] ; then printf "\n" printf " .\n" printf " : %s -h\n" "$SN" printf "\n" exit 1 fi M="$(lsusb | grep -w "$MM")" # lsusb if [[ "$M" != "" ]]; then # , if grep -w -q "$IF" /proc/net/dev; then # printf "\n" printf " %s %s\n" "$SITE" "$IF" printf "\n" if [[ "$EP" -ge 6 ]]; then printf " 5\n" exit 1 else printf " ...\n" flag="0" for i in {1..5}; do # 5 timeout -k 2 -s TERM 16 ping -w 14 -s 8 -c 1 -I "$IF" "$SITE" || flag=$((flag+1)) && printf ":%s/5 (:%s)\n" "$i" "$flag" # - if (("$flag" >= "$EP")); then break else read -r -t 1 > /dev/null fi done printf " : %s %s\n" "$flag" "$i" printf "\n" if (("$flag" >= "$EP")); then # 2 M="$(lsusb | grep "$MM")" # - printf " :\n" printf "%s\n" "$M" | cut -c 34- if ! [[ -d /sys/bus/usb/drivers/usb/"$DEV" ]]; then printf " Bus Port .\n" exit 1 else ifdown "$IF" # printf "%s" "$DEV" > "/sys/bus/usb/drivers/usb/unbind" && printf "%s" "$DEV" > "/sys/bus/usb/drivers/usb/bind" # # read -r -t 1 > /dev/null ifup "$IF" # fi fi fi else printf "\n" printf " %s \n" "$IF" printf "\n" exit 1 fi else printf " %s .\n" "$MM" fi The script is located in / usr / local / bin /.
To start the script automatically, every five minutes, add the task to cron.
crontab -e */5 * * * * /usr/local/bin/watchdog -m Huawei -s ya.ru -i wwp6s0u2i1 -n 3 -d 1-1 > /dev/null 2>&1 This is the output of dmesg, it shows a modem reset during the execution of the script.
[181709.595498] option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0 [181709.595568] option 1-1:1.0: device disconnected [181709.595798] huawei_cdc_ncm 1-1:1.1 wwp6s0u2i1: unregister 'huawei_cdc_ncm' usb-0000:06:00.0-1, Huawei CDC NCM device [181709.615005] option 1-1:1.0: GSM modem (1-port) converter detected [181709.616597] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0 [181709.623449] usb 1-1: MAC-Address: 0c:5b:8f:27:9a:64 [181709.623958] huawei_cdc_ncm 1-1:1.1: cdc-wdm0: USB WDM device [181709.624341] huawei_cdc_ncm 1-1:1.1 wwan0: register 'huawei_cdc_ncm' at usb-0000:06:00.0-1, Huawei CDC NCM device, XX:XX:XX:XX:XX:XX I’ll say right away that the script is very far from ideal, so I’m happy to accept advice and valid criticism.
Separately, I want to thank the user with Toster.ru under the nickname @AlekseyNemiro , for their help in optimizing the script.
UPD 01.22.16 Completed the script with the command to add the path to the PATH variable.
Source: https://habr.com/ru/post/275551/
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