Joachim Wiberg
c6fae88268
mDNS-SD was added in Windows 10 Creators Update[1] (build 1703), relased April 11, 2017. This makes SSDP no longer critical for finding an Infix device in Windows, both ping infix-01-02-03.local and using Chrome work. Since all major operating systems now support mDNS-SD[2] we've decided to standardize on that and LLDP for Infix and its derivatives. Other reasons for dropping it include, but is not limited to: lack of IPv6 in the implementation we use, and potential security implications[3]. [1]: https://en.wikipedia.org/wiki/Windows_10,_version_1703 [2]: https://techcommunity.microsoft.com/t5/networking-blog/mdns-in-the-enterprise/ba-p/3275777 [3]: https://blog.cloudflare.com/ssdp-100gbps/ Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
6.7 KiB
Discover Infix Units
.----. Ethernet .-------.
| PC +---------------------+ Infix |
'----' if1 eth0 '-------'
Figure 1: PC directly connected over Ethernet to Infix unit (here eth0).
When you wish to discover the IP address of an Infix switch, the simplest way is probably to ping the IPv6 all-hosts address (ff02::1) over a directly connected Ethernet cable. The unit's link-local IPv6 address is seen in the response.
In the example below, the PC is connected to Infix via interface tap0 (tap0 is if1 in Figure 1) and Infix responds with address fe80::ff:fe00:0.
linux-pc:# ping -6 -L -c 3 ff02::1%tap0
PING ff02::1%tap0(ff02::1%tap0) 56 data bytes
64 bytes from fe80::ff:fe00:0%tap0: icmp_seq=1 ttl=64 time=0.558 ms
64 bytes from fe80::ff:fe00:0%tap0: icmp_seq=2 ttl=64 time=0.419 ms
64 bytes from fe80::ff:fe00:0%tap0: icmp_seq=3 ttl=64 time=0.389 ms
--- ff02::1%tap0 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2043ms
rtt min/avg/max/mdev = 0.389/0.455/0.558/0.073 ms
linux-pc:#
The PC could connect then connect to Infix, e.g., using SSH.
linux-pc:# ssh admin@fe80::ff:fe00:0%tap0
admin@fe80::ff:fe00:0%tap0's password: admin
admin@infix-00-00-00:~$
Discovery mechanisms available in Infix
Infix advertises its presence via the mDNS and LLDP discovery protocols.
LLDP
Infix supports LLDP (IEEE 802.1AB). For a unit with factory default settings, the PC can readout the link-local IPv6 address from the Management Address TLV using tcpdump or other sniffing tools1 .
linux-pc:# tcpdump -i tap0 -Qin -v ether proto 0x88cc
tcpdump: listening on tap0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
15:51:52.061071 LLDP, length 193
Chassis ID TLV (1), length 7
Subtype MAC address (4): 02:00:00:00:00:00 (oui Unknown)
Port ID TLV (2), length 7
Subtype MAC address (3): 02:00:00:00:00:00 (oui Unknown)
Time to Live TLV (3), length 2: TTL 120s
System Name TLV (5), length 14: infix-00-00-00
System Description TLV (6), length 91
Infix by KernelKit Linux 5.19.17 #1 SMP PREEMPT_DYNAMIC Wed Jun 7 08:47:23 CEST 2023 x86_64
System Capabilities TLV (7), length 4
System Capabilities [Bridge, WLAN AP, Router, Station Only] (0x009c)
Enabled Capabilities [Station Only] (0x0080)
Management Address TLV (8), length 24
Management Address length 17, AFI IPv6 (2): fe80::ff:fe00:0
Interface Index Interface Numbering (2): 2
Port Description TLV (4), length 4: eth0
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
Link aggregation Subtype (3)
aggregation status [supported], aggregation port ID 0
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
MAC/PHY configuration/status Subtype (1)
autonegotiation [none] (0x00)
PMD autoneg capability [unknown] (0x8000)
MAU type Unknown (0x0000)
End TLV (0), length 0
^C
1 packet captured
linux-pc:#
If the unit has an IPv4 address assigned, it is shown in an additional Management Address TLV.
Note
The Management Addresses shown by LLDP are not necessarily associated with the port transmitting the LLDP message.
In the example below, the IPv4 address (10.0.1.1) happens to be assigned to eth0, while the IPv6 address (2001:db8::1) is not.
linux-pc:# sudo tcpdump -i tap0 -Qin -v ether proto 0x88cc
tcpdump: listening on tap0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
15:46:07.908665 LLDP, length 207
Chassis ID TLV (1), length 7
Subtype MAC address (4): 02:00:00:00:00:00 (oui Unknown)
Port ID TLV (2), length 7
Subtype MAC address (3): 02:00:00:00:00:00 (oui Unknown)
Time to Live TLV (3), length 2: TTL 120s
System Name TLV (5), length 14: infix-00-00-00
System Description TLV (6), length 91
Infix by KernelKit Linux 5.19.17 #1 SMP PREEMPT_DYNAMIC Wed Jun 7 08:47:23 CEST 2023 x86_64
System Capabilities TLV (7), length 4
System Capabilities [Bridge, WLAN AP, Router, Station Only] (0x009c)
Enabled Capabilities [Station Only] (0x0080)
Management Address TLV (8), length 12
Management Address length 5, AFI IPv4 (1): 10.0.1.1
Interface Index Interface Numbering (2): 2
Management Address TLV (8), length 24
Management Address length 17, AFI IPv6 (2): 2001:db8::1
Interface Index Interface Numbering (2): 3
Port Description TLV (4), length 4: eth0
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
Link aggregation Subtype (3)
aggregation status [supported], aggregation port ID 0
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
MAC/PHY configuration/status Subtype (1)
autonegotiation [none] (0x00)
PMD autoneg capability [unknown] (0x8000)
MAU type Unknown (0x0000)
End TLV (0), length 0
^C
1 packet captured
2 packets received by filter
0 packets dropped by kernel
linux-pc:#
mDNS
DNS-SD/mDNS can be used to discover Infix units and services. Infix units present their IP addresses, services and hostname within the .local domain. This method has good client support in Apple and Linux systems. On Linux, tools such as avahi-browse or mdns-scan2 can be used to search for devices advertising their services via mDNS.
linux-pc:# avahi-browse -ar
+ tap0 IPv6 infix-00-00-00 SFTP File Transfer local
+ tap0 IPv4 infix-00-00-00 SFTP File Transfer local
+ tap0 IPv6 infix-00-00-00 SSH Remote Terminal local
+ tap0 IPv4 infix-00-00-00 SSH Remote Terminal local
= tap0 IPv4 infix-00-00-00 SFTP File Transfer local
hostname = [infix-00-00-00.local]
address = [10.0.1.1]
port = [22]
txt = []
= tap0 IPv4 infix-00-00-00 SSH Remote Terminal local
hostname = [infix-00-00-00.local]
address = [10.0.1.1]
port = [22]
txt = []
= tap0 IPv6 infix-00-00-00 SFTP File Transfer local
hostname = [infix-00-00-00.local]
address = [fe80::ff:fe00:0]
port = [22]
txt = []
= tap0 IPv6 infix-00-00-00 SSH Remote Terminal local
hostname = [infix-00-00-00.local]
address = [fe80::ff:fe00:0]
port = [22]
txt = []
^C
linux-pc:#
-
lldpd: implementation of IEEE 802.1ab (LLDP) includes lldpcli, which is handy to sniff and display LLDP packets. ↩︎
-
mdns-scan: a tool for scanning for mDNS/DNS-SD published services on the local network ↩︎