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Fix prepare-tap script #46

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Fix prepare-tap script #46

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fdb417e
Fix prepare-tap script
erthalion Jun 25, 2025
b3d62bd
Use both versions of iptable
erthalion Jul 1, 2025
ae7e820
Update scripts/network/prepare-tap.sh
erthalion Jul 1, 2025
06e2d19
Update scripts/network/prepare-tap.sh
erthalion Jul 1, 2025
b48abf6
Update scripts/network/prepare-tap.sh
erthalion Jul 1, 2025
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25 changes: 13 additions & 12 deletions scripts/network/prepare-tap.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ CONFIGURE_IPTABLE="false"
CONFIGURE_FIREWALLD="false"
CONFIGURE_TUNTAP_IF_EXISTS="false"

while getopts ":a:t:u:i:fo" opt; do
while getopts ":a:t:u:ifo" opt; do
case $opt in
a) ADDRESS="${OPTARG}"
;;
Expand Down Expand Up @@ -62,34 +62,35 @@ ip link set "${NAME}" up
echo "Assigning address ${ADDRESS} to device ${NAME}..."
ip addr add "${ADDRESS}" dev "${NAME}"

echo "Enabling ip forward..."
sysctl net.ipv4.ip_forward=1

if [[ "${CONFIGURE_FIREWALLD}" == "true" ]];
then
which firewall-cmd &>/dev/null || stop "Don't have the firewal-cmd tool"

echo "Adding to the trusted zone..."
firewall-cmd --zone=trusted --add-interface="${NAME}"
firewall-cmd --zone=trusted --add-interface="${NAME}" || true
fi

echo "${CONFIGURE_IPTABLE}"
if [[ "${CONFIGURE_IPTABLE}" == "true" ]];
then
which iptables &>/dev/null || stop "Don't have the iptables tool"

echo "Enabling ip forward..."
sysctl net.ipv4.ip_forward=1
which iptables-nft &>/dev/null || stop "Don't have the iptables tool"

echo "Preparing iptable..."
iptables -t nat -A POSTROUTING -s "${ADDRESS}" -j MASQUERADE
iptables -A FORWARD -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
iptables -A FORWARD -o "${NAME}" -d "${ADDRESS}" -j ACCEPT
iptables-nft -t nat -A POSTROUTING -s "${ADDRESS}" -j MASQUERADE
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@Molter73 Molter73 Jun 26, 2025

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Would it be worth it to make some checks instead of hardcoding the iptables command to be used? Something like:

IPTABLES=iptables
if command -v iptables-nft &> /dev/null; then
  IPTABLES=iptables-nft
fi

Then you can use it like this:

Suggested change
iptables-nft -t nat -A POSTROUTING -s "${ADDRESS}" -j MASQUERADE
"${IPTABLES}" -t nat -A POSTROUTING -s "${ADDRESS}" -j MASQUERADE

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@erthalion erthalion Jun 26, 2025

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I was thinking about this, but eventually decided that this script is purely a development help for us, and since we have more or less uniform dev environment it makes little sense. But if you insist I can add this.

iptables-nft -A FORWARD -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
iptables-nft -A FORWARD -o "${NAME}" -d "${ADDRESS}" -j ACCEPT

RULE_NR=$(iptables -t filter -L INPUT --line-numbers |\
RULE_NR=$(iptables-nft -t filter -L INPUT --line-numbers |\
grep "REJECT all" |\
awk '{print $1}')

# Excempt tun device from potentiall reject all rule
if [[ $RULE_NR == "" ]]; then
iptables -I INPUT -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
iptables-nft -I INPUT -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
else
iptables -I INPUT $((RULE_NR - 1)) -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
iptables-nft -I INPUT $((RULE_NR - 1)) -i "${NAME}" -s "${ADDRESS}" -j ACCEPT
fi
fi