ipv6 dhcp replies do not arrive at dhclient
Describe the bug
We run isc dhclient to do ipv6 prefix delegation:
dhclient -P -6 ppp0 -d -v
We see packets bing transmitted (in the cli and in tcpdump if we are monitoring).
We see replies arrive at the box but do NOT see these being processed by dhclient.
These replies and up in the FORWARD iptables rule.
Issue also happens when NO firewall is active.
To Reproduce Steps to reproduce the behavior:
- see the description.
Expected behavior I'd expect the packet to be recived, dhclient doing some processing and running scripts etc.
Environment: dhcp-client-4.4.2-11.b1.fc34.x86_64 Fedora 34 kernel.org
# ip -6 a s dev ppp0
20: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc cbq state UNKNOWN group default qlen 3
inet6 fe80::c5d5:e942:39c7:7eb7 peer fe80::9ecc:83ff:fec6:e7e5/128 scope link
valid_lft forever preferred_lft forever
# lsof -p 4066992 -n
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
dhclient 4066992 root cwd DIR 254,0 4096 40961 /root
dhclient 4066992 root rtd DIR 254,0 4096 2 /
dhclient 4066992 root txt REG 254,2 2018144 141553 /usr/sbin/dhclient
dhclient 4066992 root mem REG 254,2 53728 22104 /usr/lib64/libnss_files-2.33.so
dhclient 4066992 root mem REG 254,2 1913544 21939 /usr/lib64/libc-2.33.so
dhclient 4066992 root mem REG 254,2 32696 30196 /usr/lib64/libcap-ng.so.0.0.0
dhclient 4066992 root mem REG 254,2 842360 30776 /usr/lib64/ld-2.33.so
dhclient 4066992 root 0u CHR 136,4 0t0 7 /dev/pts/4 (deleted)
dhclient 4066992 root 1u CHR 136,4 0t0 7 /dev/pts/4 (deleted)
dhclient 4066992 root 2u CHR 136,4 0t0 7 /dev/pts/4 (deleted)
dhclient 4066992 root 3u unix 0x000000001f2593f7 0t0 16525445 type=DGRAM (UNCONNECTED)
dhclient 4066992 root 4w REG 254,4 64 251 /var/lib/dhclient/dhclient6.leases
dhclient 4066992 root 5w FIFO 0,8 0t0 16525446 pipe
dhclient 4066992 root 6u IPv6 16524541 0t0 UDP [fe80::c5d5:e942:39c7:7eb7]:dhcpv6-client
# tcpdump -i ppp0 -vn port 546
dropped privs to tcpdump
tcpdump: listening on ppp0, link-type LINUX_SLL (Linux cooked v1), snapshot length 262144 bytes
06:53:09.236781 IP6 (flowlabel 0x7f0d8, hlim 1, next-header UDP (17) payload length: 60) fe80::c5d5:e942:39c7:7eb7.dhcpv6-client > ff02::1:2.dhcpv6-server: [udp sum ok] dhcp6 solicit (xid=b68ba1 (client-ID hwaddr/time type 1 time 394565497 004063f60200) (option-request DNS-server DNS-search-list) (elapsed-time 65535) (IA_PD IAID:0 T1:3600 T2:5400))
06:53:09.469530 IP6 (class 0xc0, hlim 64, next-header UDP (17) payload length: 141) fe80::9ecc:83ff:fec6:e7e5.dhcpv6-server > fe80::c5d5:e942:39c7:7eb7.dhcpv6-client: [udp sum ok] dhcp6 advertise (xid=b68ba1 (client-ID hwaddr/time type 1 time 394565497 004063f60200) (server-ID vid 0000058339633a63) (IA_PD IAID:0 T1:3600 T2:5760 (IA_PD-prefix 2001:981:a812::/48 pltime:7200 vltime:7200)) (DNS-server 2001:888:0:6::66 2001:888:0:9::99))
06:53:09.469756 IP6 (class 0xc0, hlim 63, next-header UDP (17) payload length: 141) fe80::9ecc:83ff:fec6:e7e5.dhcpv6-server > fe80::c5d5:e942:39c7:7eb7.dhcpv6-client: [udp sum ok] dhcp6 advertise (xid=b68ba1 (client-ID hwaddr/time type 1 time 394565497 004063f60200) (server-ID vid 0000058339633a63) (IA_PD IAID:0 T1:3600 T2:5760 (IA_PD-prefix 2001:981:a812::/48 pltime:7200 vltime:7200)) (DNS-server 2001:888:0:6::66 2001:888:0:9::99))
^C
Describe the solution you'd like It appears that the issue is local but what is prohibiting the replies being received?
Describe alternatives you've considered We need ipv6 PD as it is the sole mechanism the ISP gives us ipv6.