[systemd-devel] DHCPv6 configuration problem

Thomas Köller thomas at koeller.dyndns.org
Fri Feb 10 12:15:17 UTC 2023


Hi,


I encountered a problem configuring a network interface via DHCPv6, 
using the attached .network file. The interface does receive router 
announcements with the 'managed' flag set, as indicated by the following 
tcpdump output:

[root at raspi-400 ~]# tcpdump -i vpn_sarkovy -v '(icmp6 and (ip6[40] == 
133 or ip6[40] == 134)) or (udp and (port 546 or port 547))'
dropped privs to tcpdump
tcpdump: listening on vpn_sarkovy, link-type EN10MB (Ethernet), snapshot 
length 262144 bytes
12:50:04.037114 IP6 (flowlabel 0x34393, hlim 255, next-header ICMPv6 
(58) payload length: 112) _gateway > ff02::1: [icmp6 sum ok] ICMP6, 
router advertisement, length 112
     hop limit 0, Flags [managed, other stateful], pref medium, router 
lifetime 7200s, reachable time 0ms, retrans timer 0ms
       source link-address option (1), length 8 (1): 02:19:55:00:00:01
       prefix info option (3), length 32 (4): fd46:1ffa:d8e0::/48, Flags 
[onlink, auto], valid time 3600s, pref. time 1800s
       rdnss option (25), length 24 (3):  lifetime 3600s, addr: 
sarkovy.koeller.dyndns.org
       dnssl option (31), length 32 (4):  lifetime 3600s, domain(s): 
koeller.dyndns.org.

This, however, does not trigger a DHCPv6 exchange with the server.


The client computer is multi-homed, and for the other interface 
everything works as expected. Any help with this is greatly appreciated.


Thomas

-------------- next part --------------
[Match]
Name = vpn_sarkovy
Type = ether
Kind = tun

[Link]
RequiredForOnline = no
ActivationPolicy = up
Unmanaged = no

[Network]
Description = VPN tunnel interface
DHCP = ipv4
DHCPServer = no
LinkLocalAddressing = ipv6
DefaultRouteOnDevice = no
LLMNR = no
IPv6AcceptRA = yes

[DHCPv4]
IAID = 2
UseDNS = yes
UseDomains = yes
UseRoutes = yes
RouteTable = 100
AllowList = 192.168.0.0/24
RequestBroadcast = no
UseHostname = no

[DHCPv6]
IAID = 2
UseAddress = yes
UseDomains = yes
UseRoutes = yes
RouteTable = 100
UseDNS = yes

[IPv6AcceptRA]
RouterAllowList = fd46:1ffa:d8e0::/48
DHCPv6Client = yes

[RoutingPolicyRule]
Table = main
Priority = 32761
From = fd46:1ffa:d8e0::/64
To = fd46:1ffa:d8e0::/64
IncomingInterface = lo
OutgoingInterface = eth_lan
DestinationPort = 22
IPProtocol = tcp
Family = ipv6

[RoutingPolicyRule]
Table = main
Priority = 32762
From = fd46:1ffa:d8e0::/64
To = 192.168.0.0/24
IncomingInterface = eth_lan
SourcePort = 22
IPProtocol = tcp
Family = ipv6

[RoutingPolicyRule]
Table = main
Priority = 32763
From = 192.168.0.0/24
To = 192.168.0.0/24
IncomingInterface = lo
OutgoingInterface = eth_lan
DestinationPort = 22
IPProtocol = tcp
Family = ipv4

[RoutingPolicyRule]
Table = main
Priority = 32764
From = 192.168.0.0/24  
To = 192.168.0.0/24
IncomingInterface = eth_lan
SourcePort = 22
IPProtocol = tcp
Family = ipv4

[RoutingPolicyRule]
Table = 100
Priority = 32765
Family = both



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