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DHCP server fails to start due to a change in isc-dhcp-server init scripts
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In buster /etc/init.d/isc-dhcp-server changed. It now starts both v4 and v6 servers if INTERFACES, INTERFACESv4 and INTERFACESv6 are unset in /etc/default/isc-dhcp-server (as is the case in jessie).

INTERFACES is deprecated and replaced by INTERFACES{v4,v6}.


        if test -n "$INTERFACES" -a -z "$INTERFACESv4"; then
                echo "DHCPv4 interfaces are no longer set by the INTERFACES variable in" >&2
                echo "/etc/default/isc-dhcp-server.  Please use INTERFACESv4 instead." >&2
                echo "Migrating automatically for now, but this will go away in the future." >&2
        if test -n "$INTERFACESv4"; then
                echo "Launching IPv4 server only."
                start_daemon "-4" "$DHCPDv4_CONF" "$NAME4" \
                        "$DHCPDv4_PID" "$DESC4" "$INTERFACESv4"
        if test -n "$INTERFACESv6"; then
                echo "Launching IPv6 server only."
                start_daemon "-6" "$DHCPDv6_CONF" "$NAME6" \
                        "$DHCPDv6_PID" "$DESC6" "$INTERFACESv6"
        if test -z "$INTERFACESv4" -a -z "$INTERFACESv6"; then
                echo "Launching both IPv4 and IPv6 servers (please configure INTERFACES in /etc/default/isc-dhcp-server if you only want one or the other)."
                start_daemon "-4" "$DHCPDv4_CONF" "$NAME4" \
                        "$DHCPDv4_PID" "$DESC4" ""
                start_daemon "-6" "$DHCPDv6_CONF" "$NAME6" \
                        "$DHCPDv6_PID" "$DESC6" ""

We need to set the interfaces to listen to in /etc/default or modify the init script to have a working dhcp-server startup.


Difficulty level
Unknown (require assessment)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)
Issue type
Bug (incorrect behavior)

Event Timeline

jjakob created this object in space S1 VyOS Public.
jjakob updated the task description. (Show Details)
We have to ship our own /etc/{init.d,default}/isc-dhcp{v4,v6}-server files since we can't overwrite the ones supplied by the debian package.

jjakob moved this task from Need Triage to Finished on the VyOS 1.3 Equuleus board.
erkin set Issue type to Bug (incorrect behavior).Aug 31 2021, 6:06 PM