Re: [PLUG] Configuration of manual IP with commands without ifconfig

On Tue, Dec 26, 2023 at 10:18 PM Steve Litt via plug <plug@lists.phillylinux.org> wrote:

Michael Lazin via plug said on Tue, 26 Dec 2023 13:59:56 -0500

>I am hoping someone can give me hints on configuration of a manual IP
>using the "ip" command instead of ifconfig. I don't want to make a
>confrontation file just configure it manually like I used to with the
>ifconfig command. Is this possible? Thanks for your help.
>
>Michael Lazin

Hi Michael,

I can give you simple confrontrations and complex confrontrations. :-)

The following is a simple configuration to simply install a static IP
address:

====================================================
#!/bin/sh
hostname=`grep -v "^\s*#" /etc/hostname | head -n1`
ip link set dev lo up
ip link set dev enp6s1 down
ip addr add 192.168.100.188/24 dev enp6s1
ip link set dev enp6s1 up
ip route add default via 192.168.100.96
====================================================

Please understand the preceding is so simple that it can error out if
rerun: It's meant to be run once at boot time. This being said, I've
usually been able to get networking running again by simply running it
again and ignoring the error messages.

The following is a complex ip command based configuration shellscript,
with provisions to completely erase the old network config before
resetting the network, suitable for a qemu LAN-Peer:

===========================================
#!/bin/sh

use_bridge=1
use_tap=0

dev="enp40s0"
ipaddr_major="192.168.0.2"
ipaddr_minor="192.168.0.102"
gateway="192.168.0.1"

error_tap_without_bridge(){
echo -n "ERROR: Can\'t set TAP without "
echo -n "BRIDGE! "
echo Aborting...
exit 1
}

enable_ip_forwarding(){
echo 1 > /proc/sys/net/ipv4/ip_forward
}

unset_everything(){
dev=$1
ip_maj=$2
ip_min=$3
gateway=$4
ip link set dev lo down
echo "Unsetting everything for $dev, $ip_maj and $ip_min"
ip link set dev tap0 down
brctl delif br0 tap0
ip link del tap0
ip link set dev br0 down
ip addr del $ip_min/24 dev br0
ip addr del $ip_maj/24 dev br0
brctl delbr br0
ip link set dev $dev down
ip addr del $ip_min/24 dev $dev
ip addr del $ip_maj/24 dev $dev
echo ""
}

set_hostname_and_localhost(){
echo "Setting hostname and localhost"
hostname=`grep -v "^\s*#" /etc/hostname | head -n1`
ip link set dev lo up
echo ""
}

create_phys_device_link(){
dev=$1
echo Creating device link for $dev
ip link set dev $dev up
echo ""
}

set_phys_device_addr(){
dev=$1
ip_maj=$2
ip_min=$3
gateway=$4
echo -n "Setting physical device addresses "
echo -n "$ip_maj "
echo -n "and $ip_min "
echo -n "for $physdev "
echo "with gateway $gateway"
ip link set dev $dev down
ip addr add $ip_maj/24 dev $dev
ip addr add $ip_min/24 dev $dev
ip link set dev $dev up
ip route add default via $gateway
echo ""
}

set_bridge(){
dev=$1
ip_maj=$2
ip_min=$3
gateway=$4
echo Setting bridge for $dev
echo -n "Creating and setting bridge addresses "
echo -n "$ip_maj "
echo -n "and $ip_min "
echo -n "for $physdev "
echo "with gateway $gateway"

ip link add name br0 type bridge
ip link set dev $dev master br0
ip addr add $ip_maj/24 dev br0
ip addr add $ip_min/24 dev br0
ip link set dev br0 up
ip route add default via $gateway
echo ""
}

set_tap(){
echo Setting tap
ip tuntap add tap0 mode tap
brctl addif br0 tap0
ip link set dev tap0 up
echo ""
}

show_networking(){
echo -n "Networking follows in 3 seconds..."
sleep 3
echo "\n"
echo "========================================"
echo "========================================"
ip -4 link
echo "......................"
ip -4 addr
echo "......................"
ip -4 route
echo "========================================"
echo "========================================"
}

echo "\nBegin upnet.sh"

[ "$use_tap" = "1" ] && [ "$use_bridge" != "1" ] && \
error_tap_without_bridge

unset_everything $dev $ipaddr_major $ipaddr_minor $gateway

enable_ip_forwarding

set_hostname_and_localhost

create_phys_device_link $dev $ipaddr_major $ipaddr_minor $gateway

[ "$use_bridge" = "1" ] || \
set_phys_device_addr $dev $ipaddr_major $ipaddr_minor $gateway

[ "$use_bridge" = "1" ] && set_bridge $dev \
$ipaddr_major $ipaddr_minor $gateway

[ "$use_tap" = "1" ] && \
set_tap $dev $ipaddr_major $ipaddr_minor $gateway

show_networking
===========================================

SteveT

Steve Litt

Autumn 2023 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21
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