** Also affects: resolvconf (Ubuntu Noble)
Importance: Undecided
Status: New
** Also affects: wireguard (Ubuntu Noble)
Importance: Undecided
Status: New
** Also affects: resolvconf (Ubuntu Plucky)
Importance: Undecided
Status: New
** Also affects: wireguard (Ubuntu Plucky)
Importance: Undecided
Status: New
** Changed in: wireguard (Ubuntu Noble)
Status: New => Incomplete
** Changed in: wireguard (Ubuntu)
Status: Incomplete => Fix Committed
** Changed in: wireguard (Ubuntu)
Assignee: (unassigned) => Lukas Märdian (slyon)
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https://bugs.launchpad.net/bugs/2119260
Title:
Bug: resolvconf_iface_prefix returns incorrect prefix for all
interfaces
Status in resolvconf package in Ubuntu:
Invalid
Status in wireguard package in Ubuntu:
Fix Committed
Status in resolvconf source package in Noble:
New
Status in wireguard source package in Noble:
Incomplete
Status in resolvconf source package in Plucky:
New
Status in wireguard source package in Plucky:
New
Bug description:
### systemd version the issue has been seen with
systemd 255 (255.4-1ubuntu8.10)
### Used distribution
Ubuntu Desktop 24.03
### Linux kernel version used
6.8.0-71-generic
### CPU architectures issue was seen on
x86_64
### Component
resolvectl
### Expected behaviour you didn't see
WG should work even with DNS set
### Unexpected behaviour you saw
The `resolvconf_iface_prefix()` function in wg-quick returns the first
matching pattern from `/etc/resolvconf/interface-order` without
checking if the interface actually matches that pattern.
## Current broken code:
```bash
resolvconf_iface_prefix() {
[[ -f /etc/resolvconf/interface-order ]] || return 0
local iface
while read -r iface; do
[[ $iface =~ ^([A-Za-z0-9-]+)\*$ ]] || continue
echo "${BASH_REMATCH[1]}." && return 0
done < /etc/resolvconf/interface-order
}
````
## Impact
Returns "tun." for ALL interfaces when "tun*" is in interface-order
Causes DNS setup to fail for WireGuard interfaces
Affects any interface that doesn't match early patterns
### Steps to reproduce the problem
1. Run WG with DNS set
### Additional program output to the terminal or log subsystem
illustrating the issue
**Proposed fix**
```sh
resolvconf_iface_prefix() {
[[ -f /etc/resolvconf/interface-order ]] || return 0
local iface
while read -r iface; do
[[ $iface =~ ^#.*$ ]] && continue
if [[ $iface =~ ^([A-Za-z0-9-]+)\*$ ]]; then
local prefix="${BASH_REMATCH[1]}"
if [[ $INTERFACE == ${prefix}* ]]; then
echo "${prefix}."
return 0
fi
elif [[ $INTERFACE =~ $iface ]]; then
echo "$iface/"
return 0
fi
done < /etc/resolvconf/interface-order
}
```
Also added wg* to `/etc/resolvconf/interface-order`
```
# interface-order(5)
lo.inet6
lo.inet
lo.@(dnsmasq|pdnsd)
lo.!(pdns|pdns-recursor)
lo
tun*
tap*
hso*
vpn*
em+([0-9])?(_+([0-9]))*
p+([0-9])p+([0-9])?(_+([0-9]))*
en+([bcosxpP])*([^.]).inet6
en+([bcosxpP])*([^.]).ip6.@(dhclient|dhcpcd|pump|udhcpc)
en+([bcosxpP])*([^.]).inet
en+([bcosxpP])*([^.]).@(dhclient|dhcpcd|pump|udhcpc)
en+([bcosxpP])*
@(br|eth)*([^.]).inet6
@(br|eth)*([^.]).ip6.@(dhclient|dhcpcd|pump|udhcpc)
@(br|eth)*([^.]).inet
@(br|eth)*([^.]).@(dhclient|dhcpcd|pump|udhcpc)
@(br|eth)*
wl+([bcosxpP])*([^.]).inet6
wl+([bcosxpP])*([^.]).ip6.@(dhclient|dhcpcd|pump|udhcpc)
wl+([bcosxpP])*([^.]).inet
wl+([bcosxpP])*([^.]).@(dhclient|dhcpcd|pump|udhcpc)
wl+([bcosxpP])*
@(ath|wifi|wlan)*([^.]).inet6
@(ath|wifi|wlan)*([^.]).ip6.@(dhclient|dhcpcd|pump|udhcpc)
@(ath|wifi|wlan)*([^.]).inet
@(ath|wifi|wlan)*([^.]).@(dhclient|dhcpcd|pump|udhcpc)
@(ath|wifi|wlan)*
ppp*
wg* <----------------------
*
```
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: wireguard-tools 1.0.20210914-1ubuntu4 [modified: usr/bin/wg-quick]
ProcVersionSignature: Ubuntu 6.8.0-71.71-generic 6.8.12
Uname: Linux 6.8.0-71-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Aug 1 00:48:34 2025
InstallationDate: Installed on 2022-05-05 (1183 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Release amd64
(20220419)
SourcePackage: wireguard
UpgradeStatus: Upgraded to noble on 2025-07-17 (14 days ago)
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