Troubleshooting

Sometimes things break or don’t work as expected. This section describes several troubleshooting tools provided by VyOS that can help when something goes wrong.

Connectivity Tests

Basic Connectivity Tests

Verifying connectivity can be done with the familiar ping and traceroute commands. The options for each are shown (the options for each command were displayed using the built-in help as described in the Command Line Interface section and are omitted from the output here):

ping <destination>

Send ICMP echo requests to destination host. There are multiple options to ping, inkl. VRF support.

vyos@vyos:~$ ping 10.1.1.1
Possible completions:
  <Enter>       Execute the current command
  adaptive      Ping options
  allow-broadcast
  audible
  bypass-route
  count
  deadline
  do-not-fragment
  flood
  interface
  interval
  mark
  no-loopback
  numeric
  pattern
  quiet
  record-route
  size
  timestamp
  tos
  ttl
  verbose
  vrf

traceroute <destination>

Trace path to target.

vyos@vyos:~$ traceroute
Possible completions:
  <hostname>    Track network path to specified node
  <x.x.x.x>
  <h:h:h:h:h:h:h:h>
  ipv4          Track network path to <hostname|IPv4 address>
  ipv6          Track network path to <hostname|IPv6 address>

Advanced Connectivity Tests

monitor traceroute <destination>

However, another helper is available which combines ping and traceroute into a single tool. An example of its output is shown:

vyos@vyos:~$ mtr 10.62.212.12

                           My traceroute  [v0.85]
vyos (0.0.0.0)
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                  Packets               Pings
Host                            Loss%   Snt   Last   Avg  Best  Wrst StDev
1. 10.11.110.4                   0.0%    34    0.5   0.5   0.4   0.8   0.1
2. 10.62.255.184                 0.0%    34    1.1   1.0   0.9   1.4   0.1
3. 10.62.255.71                  0.0%    34    1.4   1.4   1.3   2.0   0.1
4. 10.62.212.12                  0.0%    34    1.6   1.6   1.6   1.7   0.0

Note

The output consumes the screen and will replace your command prompt.

Several options are available for changing the display output. Press h to invoke the built in help system. To quit, just press q and you’ll be returned to the VyOS command prompt.

IPv6 Topology Discovery

IPv6 uses different techniques to discover its Neighbors/topology.

Router Discovery

force ipv6-rd interface <interface> [address <ipv6-address>]

Discover routers via eth0.

Example:

vyos@vyos:~$ force ipv6-rd interface eth0
Soliciting ff02::2 (ff02::2) on eth0...

Hop limit                 :           60 (      0x3c)
Stateful address conf.    :           No
Stateful other conf.      :           No
Mobile home agent         :           No
Router preference         :         high
Neighbor discovery proxy  :           No
Router lifetime           :         1800 (0x00000708) seconds
Reachable time            :  unspecified (0x00000000)
Retransmit time           :  unspecified (0x00000000)
 Prefix                   : 240e:fe:8ca7:ea01::/64
  On-link                 :          Yes
  Autonomous address conf.:          Yes
  Valid time              :      2592000 (0x00278d00) seconds
  Pref. time              :        14400 (0x00003840) seconds
 Prefix                   : fc00:470:f1cd:101::/64
  On-link                 :          Yes
  Autonomous address conf.:          Yes
  Valid time              :      2592000 (0x00278d00) seconds
  Pref. time              :        14400 (0x00003840) seconds
 Recursive DNS server     : fc00:470:f1cd::ff00
  DNS server lifetime     :          600 (0x00000258) seconds
 Source link-layer address: 00:98:2B:F8:3F:11
 from fe80::298:2bff:fef8:3f11

Neighbor Discovery

force ipv6-nd interface <interface> address <ipv6-address>

Example:

vyos@vyos:~$ force ipv6-nd interface eth0 address fc00:470:f1cd:101::1

Soliciting fc00:470:f1cd:101::1 (fc00:470:f1cd:101::1) on eth0...
Target link-layer address: 00:98:2B:F8:3F:11 from fc00:470:f1cd:101::1

Interface names

If you find the names of your interfaces have changed, this could be because your MAC addresses have changed.

For example, you have a VyOS VM with 4 Ethernet interfaces named eth0, eth1, eth2 and eth3. Then, you migrate your VyOS VM to a different host and find your interfaces now are eth4, eth5, eth6 and eth7.

One way to fix this issue taking control of the MAC addresses is:

Log into VyOS and run this command to display your interface settings.
```
show interfaces detail
```
Take note of MAC addresses.

Now, in order to update a MAC address in the configuration, run this command specifying the interface name and MAC address you want.
```
set interfaces eth0 hw-id 00:0c:29:da:a4:fe
```
If it is a VM, go into the settings of the host and set the MAC address to the settings found in the config.boot file. You can also set the MAC to static if the host allows so.
Another example could be when cloning VyOS VMs in GNS3 and you get into the same issue: interface names have changed.

And a more generic way to fix it is just deleting every MAC address at the configuration file of the cloned machine. They will be correctly regenerated automatically.

Monitoring

VyOS features several monitoring tools.

vyos@vyos:~$ monitor
Possible completions:
  bandwidth     Monitor interface bandwidth in real time
  bandwidth-test
                Initiate or wait for bandwidth test
  cluster       Monitor clustering service
  command       Monitor an operational mode command (refreshes every 2 seconds)
  conntrack-sync
                Monitor conntrack-sync
  content-inspection
                Monitor Content-Inspection
  dhcp          Monitor Dynamic Host Control Protocol (DHCP)
  dns           Monitor a Domain Name Service (DNS) daemon
  firewall      Monitor Firewall
  https         Monitor the Secure Hypertext Transfer Protocol (HTTPS) service
  lldp          Monitor Link Layer Discovery Protocol (LLDP) daemon
  log           Monitor last lines of messages file
  nat           Monitor network address translation (NAT)
  ndp           Monitor the NDP information received by the router through the device
  openvpn       Monitor OpenVPN
  protocol      Monitor routing protocols
  snmp          Monitor Simple Network Management Protocol (SNMP) daemon
  stop-all      Stop all current background monitoring processes
  traceroute    Monitor the path to a destination in realtime
  traffic       Monitor traffic dumps
  vpn           Monitor VPN
  vrrp          Monitor Virtual Router Redundancy Protocol (VRRP)
  webproxy      Monitor Webproxy service

Traffic Dumps

To monitor interface traffic, issue the monitor traffic interface <name> command, replacing <name> with your chosen interface.

vyos@vyos:~$ monitor traffic interface eth0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:54:28.581601 IP 192.168.0.1 > vyos: ICMP echo request, id 1870, seq 3848, length 64
15:54:28.581660 IP vyos > 192.168.0.1: ICMP echo reply, id 1870, seq 3848, length 64
15:54:29.583399 IP 192.168.0.1 > vyos: ICMP echo request, id 1870, seq 3849, length 64
15:54:29.583454 IP vyos > 192.168.0.1: ICMP echo reply, id 1870, seq 3849, length 64
^C
4 packets captured
4 packets received by filter
0 packets dropped by kernel
vyos@vyos:~$

To quit monitoring, press Ctrl-c and you’ll be returned to the VyOS command prompt.

Traffic can be filtered and saved.

vyos@vyos:~$ monitor traffic interface eth0
Possible completions:
  <Enter>       Execute the current command
  filter        Monitor traffic matching filter conditions
  save          Save traffic dump from an interface to a file

Interface Bandwidth Usage

to take a quick view on the used bandwidth of an interface use the monitor bandwidth command

vyos@vyos:~$ monitor bandwidth interface eth0

show the following:

     B                      (RX Bytes/second)
00 .|....|.....................................................
00 .|....|.....................................................
00 ||..|.|.....................................................
00 ||..|.|.....................................................
00 |||||||.....................................................
00 |||||||.....................................................
       1   5   10   15   20   25   30   35   40   45   50   55   60

   KiB                      (TX Bytes/second)
67 ......|.....................................................
06 ......|.....................................................
45 ......|.....................................................
84 ......|.....................................................
22 ......|.....................................................
61 :::::||.....................................................
       1   5   10   15   20   25   30   35   40   45   50   55   60

Interface Performance

To take a look on the network bandwidth between two nodes, the monitor bandwidth-test command is used to run iperf.

vyos@vyos:~$ monitor bandwidth-test
Possible completions:
  accept        Wait for bandwidth test connections (port TCP/5001)
  initiate      Initiate a bandwidth test

The accept command opens a listening iperf server on TCP Port 5001
The initiate command connects to that server to perform the test.

vyos@vyos:~$ monitor bandwidth-test initiate
Possible completions:
  <hostname>    Initiate a bandwidth test to specified host (port TCP/5001)
  <x.x.x.x>
  <h:h:h:h:h:h:h:h>

Monitor command

The monitor command command allows you to repeatedly run a command to view a continuously refreshed output. The command is run and output every 2 seconds, allowing you to monitor the output continuously without having to re-run the command. This can be useful to follow routing adjacency formation.

vyos@router:~$ monitor command "show interfaces"

Will clear the screen and show you the output of show interfaces every 2 seconds.

Every 2.0s: /opt/vyatta/bin/vyatta-op-cmd-wrapper    Sun Mar 26 02:49:46 2019

Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface        IP Address                        S/L  Description
---------        ----------                        ---  -----------
eth0             192.168.1.1/24                    u/u
eth0.5           198.51.100.4/24                   u/u  WAN
lo               127.0.0.1/8                       u/u
                 ::1/128
vti0             172.25.254.2/30                   u/u
vti1             172.25.254.9/30                   u/u

Terminal/Console

Sometimes you need to clear counters or statistics to troubleshoot better.

To do this use the clear command in Operational mode.

to clear the console output

vyos@vyos:~$ clear console

to clear interface counters

# clear all interfaces
vyos@vyos:~$ clear interface ethernet counters
# clear specific interface
vyos@vyos:~$ clear interface ethernet eth0 counters

The command follow the same logic as the set command in configuration mode.

# clear all counters of a interface type
vyos@vyos:~$ clear interface <interface_type> counters
# clear counter of a interface in interface_type
vyos@vyos:~$ clear interface <interface_type> <interace_name> counters

to clear counters on firewall rulesets or single rules

vyos@vyos:~$ clear firewall name <ipv4 ruleset name> counters
vyos@vyos:~$ clear firewall name <ipv4 ruleset name> rule <rule#> counters

vyos@vyos:~$ clear firewall ipv6-name <ipv6 ruleset name> counters
vyos@vyos:~$ clear firewall ipv6-name <ipv6 ruleset name> rule <rule#> counters

System Information

Boot Steps

VyOS 1.2 uses Debian Jessie as the base Linux operating system. Jessie was the first version of Debian that uses systemd as the default init system.

These are the boot steps for VyOS 1.2

The BIOS loads Grub (or isolinux for the Live CD)
Grub then starts the Linux boot and loads the Linux Kernel /boot/vmlinuz
Kernel Launches Systemd /lib/systemd/systemd
Systemd loads the VyOS service file /lib/systemd/system/vyos-router.service
The service file launches the VyOS router init script /usr/libexec/vyos/init/vyos-router - this is part of the vyatta-cfg Debian package

Starts FRR - successor to GNU Zebra and Quagga

Initialises the boot configuration file - copies over config.boot.default if there is no configuration

Runs the configuration migration, if the configuration is for an older version of VyOS

Runs The pre-config script, if there is one /config/scripts/vyos-preconfig-bootup.script

If the config file was upgraded, runs any post upgrade scripts /config/scripts/post-upgrade.d

Starts rl-system and firewall

Mounts the /boot partition

The boot configuration file is then applied by /opt/vyatta/sbin/ vyatta-boot-config-loader/opt/vyatta/etc/config/config.boot

The config loader script writes log entries to /var/log/vyatta-config-loader.log

Runs telinit q to tell the init system to reload /etc/inittab

Finally it runs the post-config script /config/scripts/vyos-postconfig-bootup.script