[GH-ISSUE #3107] amn0 interface assigned /32 prefix instead of correct CIDR — no traffic passes (fix in PR #2840 not in 5.0.1.5) #1440

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opened 2026-10-13 20:42:31 +00:00 by bsakaguchi · 0 comments

bsakaguchi commented

2026-10-13 20:42:31 +00:00

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Originally created by @15ags on GitHub (Aug 31, 2026).
Original GitHub issue: https://github.com/amnezia-vpn/amnezia-client/issues/3107

Describe the bug
The AmneziaVPN client assigns the wrong IPv4 prefix length to the amn0 interface. Instead of assigning the correct CIDR (e.g. /24), it assigns /32, making the interface unusable for routing. All traffic routed through amn0 (0.0.0.0/1 and 128.0.0.0/1) is dropped because the interface has an invalid IP configuration. This is the same bug as #1089, #1647, #2048, which was fixed in PR #2840 but the fix is not present in the latest .run installer (5.0.1.5).
To Reproduce

Install AmneziaVPN via the .run installer
Connect to an AmneziaWG server
Run ip addr show amn0 — see inet x.x.x.x/32 (wrong /32 prefix)
Run ping -c 3 8.8.8.8 — 100% packet loss
Run ip route show — routes go through amn0 but traffic is blackholed
Expected behavior
The client should assign the correct CIDR prefix (e.g. /24) to amn0 so that traffic can be routed through the tunnel, as specified in the VPN config Address field.
Workaround
After connecting, run manually:
sudo ip addr del <assigned_ip>/32 dev amn0
sudo ip addr add <config_ip>/24 dev amn0
Log files
AmneziaVPN.log:
[2026-08-31 16:58:36.275Z] [DEBUG] AmneziaVPN : "Trying to connect to VPN, container is amnezia-awg, route mode is" amnezia::route_mode_ns::VpnOnlyForwardSites
[2026-08-31 16:58:36.290Z] [DEBUG] AmneziaVPN : "Site split tunneling is disabled, route mode is 0"
[2026-08-31 16:58:37.153Z] [DEBUG] AmneziaVPN : VpnProtocol::setConnectionState "Connected"
[2026-08-31 16:58:37.154Z] [DEBUG] AmneziaVPN : Connection state: 'Connected'
Interface output after connection:
amn0: <POINTOPOINT,PROMISC,UP,LOWER_UP> mtu 1280
inet x.x.x.x/32 scope global amn0 ← wrong, should be /24
Routes:
0.0.0.0/1 dev amn0 metric 1
128.0.0.0/1 dev amn0 metric 1
Desktop:

OS: Arch Linux x86_64
Version: AmneziaVPN 5.0.1.5 installed via .run
Server:
Protocol: AmneziaWG
Additional context
PR #2840 ("fix(linux): preserve IPv4 interface host and prefix") merged Jul 17, 2026 appears to fix this exact issue, but the fix is not included in version 5.0.1.5 available from the .run installer. The bug has been reported in #1089, #1357, #1647, #1731, #2048, #2483, #2573 — all with the same root cause (amn0 gets /32 prefix instead of the correct CIDR). Please include this fix in the next release.

Originally created by @15ags on GitHub (Aug 31, 2026). Original GitHub issue: https://github.com/amnezia-vpn/amnezia-client/issues/3107 Describe the bug The AmneziaVPN client assigns the wrong IPv4 prefix length to the amn0 interface. Instead of assigning the correct CIDR (e.g. /24), it assigns /32, making the interface unusable for routing. All traffic routed through amn0 (0.0.0.0/1 and 128.0.0.0/1) is dropped because the interface has an invalid IP configuration. This is the same bug as #1089, #1647, #2048, which was fixed in PR #2840 but the fix is not present in the latest .run installer (5.0.1.5). To Reproduce 1. Install AmneziaVPN via the .run installer 2. Connect to an AmneziaWG server 3. Run ip addr show amn0 — see inet x.x.x.x/32 (wrong /32 prefix) 4. Run ping -c 3 8.8.8.8 — 100% packet loss 5. Run ip route show — routes go through amn0 but traffic is blackholed Expected behavior The client should assign the correct CIDR prefix (e.g. /24) to amn0 so that traffic can be routed through the tunnel, as specified in the VPN config Address field. Workaround After connecting, run manually: sudo ip addr del <assigned_ip>/32 dev amn0 sudo ip addr add <config_ip>/24 dev amn0 Log files AmneziaVPN.log: [2026-08-31 16:58:36.275Z] [DEBUG] AmneziaVPN : "Trying to connect to VPN, container is amnezia-awg, route mode is" amnezia::route_mode_ns::VpnOnlyForwardSites [2026-08-31 16:58:36.290Z] [DEBUG] AmneziaVPN : "Site split tunneling is disabled, route mode is 0" [2026-08-31 16:58:37.153Z] [DEBUG] AmneziaVPN : VpnProtocol::setConnectionState "Connected" [2026-08-31 16:58:37.154Z] [DEBUG] AmneziaVPN : Connection state: 'Connected' Interface output after connection: amn0: <POINTOPOINT,PROMISC,UP,LOWER_UP> mtu 1280 inet x.x.x.x/32 scope global amn0 ← wrong, should be /24 Routes: 0.0.0.0/1 dev amn0 metric 1 128.0.0.0/1 dev amn0 metric 1 Desktop: - OS: Arch Linux x86_64 - Version: AmneziaVPN 5.0.1.5 installed via .run Server: - Protocol: AmneziaWG Additional context PR #2840 ("fix(linux): preserve IPv4 interface host and prefix") merged Jul 17, 2026 appears to fix this exact issue, but the fix is not included in version 5.0.1.5 available from the .run installer. The bug has been reported in #1089, #1357, #1647, #1731, #2048, #2483, #2573 — all with the same root cause (amn0 gets /32 prefix instead of the correct CIDR). Please include this fix in the next release.

bsakaguchi referenced this issue

2026-10-13 21:21:12 +00:00

[PR #1440] [MERGED] feature/subscription settings page #2351