wit-network-config/debian/wit-network-config.postinst

#!/bin/bash
# postinst script for #PACKAGE#
#
# see: dh_installdeb(1)

set -e

# summary of how this script can be called:
#        * <postinst> `configure' <most-recently-configured-version>
#        * <old-postinst> `abort-upgrade' <new version>
#        * <conflictor's-postinst> `abort-remove' `in-favour' <package>
#          <new-version>
#        * <postinst> `abort-remove'
#        * <deconfigured's-postinst> `abort-deconfigure' `in-favour'
#          <failed-install-package> <version> `removing'
#          <conflicting-package> <version>
# for details, see https://www.debian.org/doc/debian-policy/ or
# the debian-policy package

case "$1" in
    configure)


        IFCONFIG="/etc/network/interfaces"
        UDEVCONFIG="/etc/udev/rules.d/70-persistent-net.rules"
        FRRCONFIG="/etc/frr/frr.conf.wit"
        IPSECCONFIG="/etc/ipsec.conf.wit"


     ## START gather all the info from the box and generate the variabels

        dig_txt() {
            TMPDIG=$(dig txt +short $1)
            [ -z $TMPDIG ] && exit 2
            TMPDIG=${TMPDIG//\//\\\/}
            TMPDIG=${TMPDIG//\"/}   #" fix the god damn syntax highlighter
            echo ${TMPDIG}
        }


        LOOPBACKv4=$(dig a +short ${HOSTNAME})
        LOOPBACKv6=$(dig aaaa +short ${HOSTNAME})
        NODEASN=$(dig_txt asn.${HOSTNAME})

        if [ -z $LOOPBACKv4 ] || [ -z $LOOPBACKv6 ] || [ -z $NODEASN ]; then
            echo "unable to find my LOOPBACK IP and/or ASN: $LOOPBACKv4/$LOOPBACKv6/$NODEASN"
            exit 2
        fi


     ## END variables


     ## START nic config compile


      # wiping existing config in prep for re-deploying it
        mv -f ${IFCONFIG} ${IFCONFIG}.dpkg-old || true
        mv -f ${UDEVCONFIG} ${UDEVCONFIG}.dpkg-old || true





       # write loopback config
        cat <<-EOF >>$IFCONFIG
		auto lo
		iface lo inet loopback

		iface lo inet static
		    address ${LOOPBACKv4}/32

		iface lo inet6 static
		    address ${LOOPBACKv6}/128


	EOF



      # gathering defined interfaces
        for if in mgmt mgmtgw ipmigw feth up ibgp gre;   do
          for i in {1..4};    do                #### for now we support/count only to 4 interfaces of each type, we can just raise this to whatever number we want (exeption mgmt)
            ifname=${if}${i}
            ifalias=$(dig_txt name.${ifname}.${HOSTNAME}) || true  ## still thinking how to do this cleaner


            if [[ $ifname = gre? ]] && [[ ! -z $ifalias ]]; then
                ifmtu=$(dig_txt mtu.${ifname}.${HOSTNAME})
                local=$(dig_txt local.${ifname}.${HOSTNAME})
                localasn=$(dig_txt localasn.${ifname}.${HOSTNAME})
                remote=$(dig_txt remote.${ifname}.${HOSTNAME})


                ## for the GRE tunnel to not have to deal with ibgp/full-mesh or reflectors prepending a private AS
                FRR_GRE_ASN="$localasn"


                ## build FRR interface config to enable ND adv for ipv6 unmanaged
                FRR_IFS="${FRR_IFS}interface $ifname\n"
                FRR_IFS="${FRR_IFS} description $ifalias\n"
                FRR_IFS="${FRR_IFS} ipv6 nd ra-interval 10\n"
                FRR_IFS="${FRR_IFS} no ipv6 nd suppress-ra\n!\n"


                ## build FRR neightbor interfaces
                FRR_EDGE_NEIGH=" !!!  neighbor $ifname interface peer-group GRE\n$FRR_EDGE_NEIGH"


                ## build regular linux network interface config
                cat <<-EOF >>$IFCONFIG
			auto $ifname
			iface $ifname inet manual
			    ## $ifalias
			    pre-up ip tunnel add $ifname mode gre local $local remote $remote
			    down ip tunnel del $ifname
			    mtu $ifmtu


		EOF

            fi


            ## blow we deal with real physical interfaces
            ## it is crucial that this `ifmac` block is above the rest, since if no mac is returned it will skip the loop and prevent the package install to fail
            if [[ $if = mgmt ]] || [[ $if = mgmtgw ]] || [[ $if = ipmigw ]]
              then
                ifmac=$(dig_txt mac.${if}.${HOSTNAME}) || continue      ## at this point skip the rest of the loop for interfaces that do not have a mac defined (those are not physical)
              else
                ifmac=$(dig_txt mac.${ifname}.${HOSTNAME}) || continue      ## at this point skip the rest of the loop for interfaces that do not have a mac defined (those are not physical)
            fi
            echo 'SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="'${ifmac}'", ATTR{type}=="1", NAME="'${ifname}'"' >>$UDEVCONFIG


            if [[ $ifname = up? ]]; then

                ipv4=$(dig_txt ipv4.$ifname.${HOSTNAME})
                ipv6=$(dig_txt ipv6.$ifname.${HOSTNAME})
                peerv4=$(dig_txt peerv4.$ifname.${HOSTNAME}) || true  ## we dont know if we will always have both available
                peerv6=$(dig_txt peerv6.$ifname.${HOSTNAME}) || true  ## we dont know if we will always have both available


                [ -z $peerv4 ] || FRR_EDGE_NEIGH=" !!!  neighbor $peerv4 peer-group eBGPv4\n$FRR_EDGE_NEIGH"
                [ -z $peerv6 ] || FRR_EDGE_NEIGH=" !!!  neighbor $peerv6 peer-group eBGPv6\n$FRR_EDGE_NEIGH"


                cat <<-EOF >>$IFCONFIG
			auto $ifname
			iface $ifname inet static
			    address ${ipv4/\\/}
			    mtu 9000

			iface $ifname inet6 static
			    address ${ipv6/\\/}
			    dad-attempts 0


		EOF

            fi


            if [[ $ifname = ibgp? ]]; then

                ## build FRR interface config to enable ND adv for ipv6 unmanaged
                FRR_IFS="${FRR_IFS}interface $ifname\n"
                FRR_IFS="${FRR_IFS} ipv6 nd ra-interval 10\n"
                FRR_IFS="${FRR_IFS} no ipv6 nd suppress-ra\n!\n"


                ## build FRR neightbor interfaces
                FRR_EDGE_NEIGH=" !!!  neighbor $ifname interface peer-group iBGP\n$FRR_EDGE_NEIGH"

                cat <<-EOF >>$IFCONFIG
			auto $ifname
			iface $ifname inet manual
			    mtu 9000


		EOF
            fi


            if [[ $ifname = feth? ]]; then
                cat <<-EOF >>$IFCONFIG
			auto $ifname
			iface $ifname inet manual
			    mtu 9000


		EOF
            fi


            if [[ $ifname = mgmt1 ]]; then            ## only 1 mgmt interface supported for now
                cat <<-EOF >>$IFCONFIG
			auto $ifname
			iface $ifname inet6 auto
			iface $ifname inet dhcp
			    pre-up /bin/ip link add mgmt type vrf table mgmt
			    pre-up /bin/ip link set up dev mgmt
			    pre-up /bin/ip link set master mgmt dev $ifname
			    post-down /bin/ip link del dev mgmt


		EOF
            fi

          done
        done

     ## STOP nic config compile


     ## START compiling frr and ipsec dynamic config blocks

         ## compile public IP space prefix lists, this is what's going to be advertised out the upstream provider
            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv4.public.prefixlist.usw2.admin.wit.com)" || break
                TEMPAGGS="  !!!  aggregate-address ${TEMP}\n"
                FRR_IPV4_EDGE_SUMMARIES_AGGREGATS="${FRR_IPV4_EDGE_SUMMARIES_AGGREGATS}${TEMPAGGS}"
                TEMPSUM="!!!  ip prefix-list WITv4-SUMMARIES seq $((i*5)) permit ${TEMP}\n"
                FRR_IPV4_EDGE_SUMMARIES_PFLIST="${FRR_IPV4_EDGE_SUMMARIES_PFLIST}${TEMPSUM}"
                let i+=1
            done

            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv6.public.prefixlist.usw2.admin.wit.com)" || break
                TEMPAGGS="  !!!  aggregate-address ${TEMP}\n"
                FRR_IPV6_EDGE_SUMMARIES_AGGREGATS="${FRR_IPV6_EDGE_SUMMARIES_AGGREGATS}${TEMPAGGS}"
                TEMPSUM="!!!  ipv6 prefix-list WITv6-SUMMARIES seq $((i*5)) permit ${TEMP}\n"
                FRR_IPV6_EDGE_SUMMARIES_PFLIST="${FRR_IPV6_EDGE_SUMMARIES_PFLIST}${TEMPSUM}"
                let i+=1
            done


         ## compile customer IP blocks that we accept. this in theory should be a combination of *all* public blocks used accross regions while limiting it a smaller subnet size
            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv4.customers.prefixlist.usw2.admin.wit.com)" || break
                TEMPSUM="ip prefix-list WITv4-CUSTOMERS seq $((i*5)) permit ${TEMP} ge 25\n"
                FRR_IPV4_CUSTOMERS_PFLIST="${FRR_IPV4_CUSTOMERS_PFLIST}${TEMPSUM}"
                let i+=1
            done

            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv6.customers.prefixlist.usw2.admin.wit.com)" || break
                TEMPSUM="ipv6 prefix-list WITv6-CUSTOMERS seq $((i*5)) permit ${TEMP} ge 64\n"
                FRR_IPV6_CUSTOMERS_PFLIST="${FRR_IPV6_CUSTOMERS_PFLIST}${TEMPSUM}"
                let i+=1
            done


         ## compile loopback IP blocks that we wanna accept to be injected into the bgp
            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv4.loopback.prefixlist.usw2.admin.wit.com)" || break
                TEMPSUM="ip prefix-list LOOPBACKv4 seq $((i*5)) permit ${TEMP} ge 32\n"
                FRR_IPV4_LOOPBACK_PFLIST="${FRR_IPV4_LOOPBACK_PFLIST}${TEMPSUM}"
                [ -z $IPSEC_IPV4_SUBNETS ] || IPSEC_IPV4_SUBNETS="${IPSEC_IPV4_SUBNETS},"
                IPSEC_IPV4_SUBNETS="${IPSEC_IPV4_SUBNETS}${TEMP}"
                let i+=1
            done

            i=1
            while true; do 
                TEMP="$(dig_txt $i.ipv6.loopback.prefixlist.usw2.admin.wit.com)" || break
                TEMPSUM="ipv6 prefix-list LOOPBACKv6 seq $((i*5)) permit ${TEMP} ge 128\n"
                FRR_IPV6_LOOPBACK_PFLIST="${FRR_IPV6_LOOPBACK_PFLIST}${TEMPSUM}"
                [ -z $IPSEC_IPV6_SUBNETS ] || IPSEC_IPV6_SUBNETS="${IPSEC_IPV6_SUBNETS},"
                IPSEC_IPV6_SUBNETS="${IPSEC_IPV6_SUBNETS}${TEMP}"
                let i+=1
            done

     ## STOP compiling frr config


     ## START writing config files


      # set frr config
        sed -i \
                -e "s/^!!! FRR_IFS/$FRR_IFS/" \
                -e "s/^ !!! FRR_EDGE_NEIGH/$FRR_EDGE_NEIGH/"  \
                -e "s/^  !!! FRR_IPV4_EDGE_SUMMARIES_AGGREGATS/$FRR_IPV4_EDGE_SUMMARIES_AGGREGATS/"  \
                -e "s/^  !!! FRR_IPV6_EDGE_SUMMARIES_AGGREGATS/$FRR_IPV6_EDGE_SUMMARIES_AGGREGATS/"  \
                -e "s/^!!! FRR_IPV4_EDGE_SUMMARIES_PFLIST/$FRR_IPV4_EDGE_SUMMARIES_PFLIST/"  \
                -e "s/^!!! FRR_IPV6_EDGE_SUMMARIES_PFLIST/$FRR_IPV6_EDGE_SUMMARIES_PFLIST/"  \
                -e "s/^!!! FRR_IPV4_CUSTOMERS_PFLIST/$FRR_IPV4_CUSTOMERS_PFLIST/"  \
                -e "s/^!!! FRR_IPV6_CUSTOMERS_PFLIST/$FRR_IPV6_CUSTOMERS_PFLIST/"  \
                -e "s/^!!! FRR_IPV4_LOOPBACK_PFLIST/$FRR_IPV4_LOOPBACK_PFLIST/"  \
                -e "s/^!!! FRR_IPV6_LOOPBACK_PFLIST/$FRR_IPV6_LOOPBACK_PFLIST/"  \
                -e "s/FRR_GRE_ASN/${FRR_GRE_ASN}/"  \
                -e "s/FRRROUTERID/${LOOPBACKv4}/" \
                -e "s/NODEASN/${NODEASN}/"  \
                $FRRCONFIG
        [ -z $FRR_EDGE_NEIGH ] || sed -i -e 's/!!!  //' $FRRCONFIG



      # set ipsec config
        sed -i \
                -e "s/FQHOSTNAME/${HOSTNAME}/" \
                -e "s/LOOPBACKv4/${LOOPBACKv4}\/32/" \
                -e "s/LOOPBACKv6/${LOOPBACKv6}\/128/" \
                -e "s/IPSEC_IPV4_SUBNETS/$IPSEC_IPV4_SUBNETS/" \
                -e "s/IPSEC_IPV6_SUBNETS/$IPSEC_IPV6_SUBNETS/" \
                $IPSECCONFIG

        echo ": RSA ${HOSTNAME}.key" >/etc/ipsec.secrets


        chown frr.frr $FRRCONFIG /etc/frr/daemons.wit



      # wite grub rules for serial terminal
        sed -i -e '/GRUB_CMDLINE_LINUX_DEFAULT=/d' -e '/GRUB_CMDLINE_LINUX=/d' -e '/GRUB_SERIAL_COMMAND=/d' -e '/GRUB_TERMINAL=/d' /etc/default/grub
        cat <<-EOF >>/etc/default/grub
		GRUB_CMDLINE_LINUX_DEFAULT=""
		GRUB_CMDLINE_LINUX="console=tty0 console=ttyS1,115200n8"
		GRUB_TERMINAL=serial
		GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=1 --word=8 --parity=no --stop=1"
	EOF


      # disable password logins on ssh
        sed -i -e '/#*\s*PasswordAuthentication /d' /etc/ssh/sshd_config
        echo "PasswordAuthentication no" >>/etc/ssh/sshd_config


    ## END config file section


    ## START configuring services as we need it

        systemctl disable strongswan    # disable ipsec till we have the certs and all ansible will enable it after dropping certs
        systemctl enable firewall
        systemctl restart systemd-timesyncd
        systemctl restart ssh
        
        update-grub
        
        sysctl -p /etc/sysctl.d/10-frr.conf

    ## END services section


    ;;

    abort-upgrade|abort-remove|abort-deconfigure)
    ;;

    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.

#DEBHELPER#

exit 0