Hi there, Dave A said this was the mailer to send this to:
I’ve been using my management interface in a VRF for several months now and it’s worked perfectly – I’ve been able to update/upgrade the packages just fine and iptables works excellently with it – exactly as I needed. Since Kernel 5 though I am no longer able to update – but the issue is quite a curious one as some traffic appears to be fine (DNS lookups use VRF correctly) but others don’t (updating/upgrading the packages) I have on this device 2 interfaces: Eth0 for management – inbound SSH, DNS, updates/upgrades Eth1 for managing other boxes (ansible using SSH) Link and addr info shown below: Admin@NETM06:~$ ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master mgmt-vrf state UP mode DEFAULT group default qlen 1000 link/ether 00:22:48:07:cc:ad brd ff:ff:ff:ff:ff:ff 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 00:22:48:07:c9:6c brd ff:ff:ff:ff:ff:ff 4: mgmt-vrf: <NOARP,MASTER,UP,LOWER_UP> mtu 65536 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 8a:f6:26:65:02:5a brd ff:ff:ff:ff:ff:ff Admin@NETM06:~$ ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master mgmt-vrf state UP group default qlen 1000 link/ether 00:22:48:07:cc:ad brd ff:ff:ff:ff:ff:ff inet 10.24.12.10/24 brd 10.24.12.255 scope global eth0 valid_lft forever preferred_lft forever inet6 fe80::222:48ff:fe07:ccad/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 00:22:48:07:c9:6c brd ff:ff:ff:ff:ff:ff inet 10.24.12.9/24 brd 10.24.12.255 scope global eth1 valid_lft forever preferred_lft forever inet6 fe80::222:48ff:fe07:c96c/64 scope link valid_lft forever preferred_lft forever 4: mgmt-vrf: <NOARP,MASTER,UP,LOWER_UP> mtu 65536 qdisc noqueue state UP group default qlen 1000 link/ether 8a:f6:26:65:02:5a brd ff:ff:ff:ff:ff:ff the production traffic is all in the 10.0.0.0/8 network (eth1 global VRF) except for a few subnets (DNS) which are routed out eth0 (mgmt-vrf) Admin@NETM06:~$ ip route show default via 10.24.12.1 dev eth0 10.0.0.0/8 via 10.24.12.1 dev eth1 10.24.12.0/24 dev eth1 proto kernel scope link src 10.24.12.9 10.24.65.0/24 via 10.24.12.1 dev eth0 10.25.65.0/24 via 10.24.12.1 dev eth0 10.26.0.0/21 via 10.24.12.1 dev eth0 10.26.64.0/21 via 10.24.12.1 dev eth0 Admin@NETM06:~$ ip route show vrf mgmt-vrf default via 10.24.12.1 dev eth0 unreachable default metric 4278198272 10.24.12.0/24 dev eth0 proto kernel scope link src 10.24.12.10 10.24.65.0/24 via 10.24.12.1 dev eth0 10.25.65.0/24 via 10.24.12.1 dev eth0 10.26.0.0/21 via 10.24.12.1 dev eth0 10.26.64.0/21 via 10.24.12.1 dev eth0 The strange activity occurs when I enter the command “sudo apt update” as I can resolve the DNS request (10.24.65.203 or 10.24.64.203, verified with tcpdump) out eth0 but for the actual update traffic there is no activity: sudo tcpdump -i eth0 '(host 10.24.65.203 or host 10.25.65.203) and port 53' -n <OUTPUT OMITTED FOR BREVITY> 10:06:05.268735 IP 10.24.12.10.39963 > 10.24.65.203.53: 48798+ [1au] A? security.ubuntu.com. (48) <OUTPUT OMITTED FOR BREVITY> 10:06:05.284403 IP 10.24.65.203.53 > 10.24.12.10.39963: 48798 13/0/1 A 91.189.91.23, A 91.189.88.24, A 91.189.91.26, A 91.189.88.162, A 91.189.88.149, A 91.189.91.24, A 91.189.88.173, A 91.189.88.177, A 91.189.88.31, A 91.189.91.14, A 91.189.88.176, A 91.189.88.175, A 91.189.88.174 (256) You can see that the update traffic is returned but is not accepted by the stack and a RST is sent Admin@NETM06:~$ sudo tcpdump -i eth0 '(not host 168.63.129.16 and port 80)' -n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes 10:17:12.690658 IP 10.24.12.10.40216 > 91.189.88.175.80: Flags [S], seq 2279624826, win 64240, options [mss 1460,sackOK,TS val 2029365856 ecr 0,nop,wscale 7], length 0 10:17:12.691929 IP 10.24.12.10.52362 > 91.189.95.83.80: Flags [S], seq 1465797256, win 64240, options [mss 1460,sackOK,TS val 3833463674 ecr 0,nop,wscale 7], length 0 10:17:12.696270 IP 91.189.88.175.80 > 10.24.12.10.40216: Flags [S.], seq 968450722, ack 2279624827, win 28960, options [mss 1418,sackOK,TS val 81957103 ecr 2029365856,nop,wscale 7], length 0 10:17:12.696301 IP 10.24.12.10.40216 > 91.189.88.175.80: Flags [R], seq 2279624827, win 0, length 0 10:17:12.697884 IP 91.189.95.83.80 > 10.24.12.10.52362: Flags [S.], seq 4148330738, ack 1465797257, win 28960, options [mss 1418,sackOK,TS val 2257624414 ecr 3833463674,nop,wscale 8], length 0 10:17:12.697909 IP 10.24.12.10.52362 > 91.189.95.83.80: Flags [R], seq 1465797257, win 0, length 0 I can emulate the DNS lookup using netcat in the vrf: sudo ip vrf exec mgmt-vrf nc -u 10.24.65.203 53 then interactively enter the binary for a www.google.co.uk request: 0035624be394010000010000000000010377777706676f6f676c6502636f02756b00000100010000290200000000000000 This returns as expected: 00624be394010000010000000000010377777706676f6f676c6502636f02756b00000100010000290200000000000000 I can run: Admin@NETM06:~$ host www.google.co.uk www.google.co.uk has address 172.217.169.3 www.google.co.uk has IPv6 address 2a00:1450:4009:80d::2003 but I get a timeout for: sudo ip vrf exec mgmt-vrf host www.google.co.uk ;; connection timed out; no servers could be reached However I can take a repo address and vrf exec to it on port 80: Admin@NETM06:~$ sudo ip vrf exec mgmt-vrf nc 91.189.91.23 80 hello HTTP/1.1 400 Bad Request <OUTPUT OMITTED> My iptables rule: sudo iptables -Z Admin@NETM06:~$ sudo iptables -L -v Chain INPUT (policy DROP 16 packets, 3592 bytes) pkts bytes target prot opt in out source destination 44 2360 ACCEPT tcp -- any any anywhere anywhere tcp spt:http ctstate RELATED,ESTABLISHED 83 10243 ACCEPT udp -- any any anywhere anywhere udp spt:domain ctstate RELATED,ESTABLISHED I cannot find out why the update isn’t working. Any help greatly appreciated Kind Regards, Gareth
