mirror of
https://github.com/kernelkit/infix.git
synced 2026-07-31 13:03:02 +02:00
Joachim Wiberg
7804787201
Overhaul text and grammar. Simplify, correct, and add information about the new mDNS settings. Replace 'unit' with 'device', which is the more common term for hardware. Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
325 lines
11 KiB
Markdown
325 lines
11 KiB
Markdown
# Discover Devices
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Infix advertises itself via the [mDNS-SD](#mdns-sd) and [LLDP](#lldp)
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discovery protocols. mDNS-SD has good client support in Windows, macOS
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and on Linux systems. More on these protocols later.
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An even simpler method is available when directly attached to an Infix
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device:
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```
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.----. Ethernet .-------.
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| PC +---------------------+ Infix |
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'----' if1 e1 '-------'
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```
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With IPv6 you can *ping the all-hosts* address (ff02::1), the device's
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link-local IPv6 address is then seen in the response. In the following
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example, the PC here uses *tap0* as *if1*, Infix responds with address
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*fe80::ff:fec0:ffed*.
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```
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linux-pc:# ping -6 -L -c 3 ff02::1%tap0
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PING ff02::1%tap0(ff02::1%tap0) 56 data bytes
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64 bytes from fe80::ff:fec0:ffed%tap0: icmp_seq=1 ttl=64 time=0.558 ms
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64 bytes from fe80::ff:fec0:ffed%tap0: icmp_seq=2 ttl=64 time=0.419 ms
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64 bytes from fe80::ff:fec0:ffed%tap0: icmp_seq=3 ttl=64 time=0.389 ms
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--- ff02::1%tap0 ping statistics ---
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3 packets transmitted, 3 received, 0% packet loss, time 2043ms
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rtt min/avg/max/mdev = 0.389/0.455/0.558/0.073 ms
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linux-pc:#
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```
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> [!TIP]
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> The `-L` option ignores local responses from the PC.
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This address can then be used to connect to the device, e.g., using SSH.
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Notice the syntax `username@address%interface`:
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```
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linux-pc:# ssh admin@fe80::ff:fec0:ffed%tap0
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admin@fe80::ff:fec0:ffed%tap0's password: admin
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admin@infix-c0-ff-ee:~$
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```
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## LLDP
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Infix supports LLDP (IEEE 802.1AB). For a device with factory default
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settings, the link-local IPv6 address can be read from the Management
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Address TLV using *tcpdump* or other sniffing tools[^1]:
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```
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linux-pc:# tcpdump -i tap0 -Qin -v ether proto 0x88cc
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tcpdump: listening on tap0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
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15:51:52.061071 LLDP, length 193
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Chassis ID TLV (1), length 7
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Subtype MAC address (4): 02:00:00:c0:ff:ee (oui Unknown)
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Port ID TLV (2), length 7
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Subtype MAC address (3): 02:00:00:c0:ff:ee (oui Unknown)
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Time to Live TLV (3), length 2: TTL 120s
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System Name TLV (5), length 14: infix-c0-ff-ee
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System Description TLV (6), length 91
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Infix by KernelKit Linux 5.19.17 #1 SMP PREEMPT_DYNAMIC Wed Jun 7 08:47:23 CEST 2023 x86_64
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System Capabilities TLV (7), length 4
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System Capabilities [Bridge, WLAN AP, Router, Station Only] (0x009c)
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Enabled Capabilities [Station Only] (0x0080)
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Management Address TLV (8), length 24
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Management Address length 17, AFI IPv6 (2): fe80::ff:fec0:ffed
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Interface Index Interface Numbering (2): 2
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Port Description TLV (4), length 4: eth0
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Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
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Link aggregation Subtype (3)
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aggregation status [supported], aggregation port ID 0
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Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
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MAC/PHY configuration/status Subtype (1)
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autonegotiation [none] (0x00)
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PMD autoneg capability [unknown] (0x8000)
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MAU type Unknown (0x0000)
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End TLV (0), length 0
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^C
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1 packet captured
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linux-pc:#
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```
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If the device has an IPv4 address assigned, it is shown in an additional
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Management Address TLV.
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> [!NOTE]
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> The Management Addresses shown by LLDP are not necessarily associated
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> with the port transmitting the LLDP message.
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In the example below, the IPv4 address (10.0.1.1) happens to be
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assigned to *eth0*, while the IPv6 address (2001:db8::1) is not.
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```
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linux-pc:# sudo tcpdump -i tap0 -Qin -v ether proto 0x88cc
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tcpdump: listening on tap0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
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15:46:07.908665 LLDP, length 207
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Chassis ID TLV (1), length 7
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Subtype MAC address (4): 02:00:00:c0:ff:ee (oui Unknown)
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Port ID TLV (2), length 7
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Subtype MAC address (3): 02:00:00:c0:ff:ee (oui Unknown)
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Time to Live TLV (3), length 2: TTL 120s
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System Name TLV (5), length 14: infix-c0-ff-ee
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System Description TLV (6), length 91
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Infix by KernelKit Linux 5.19.17 #1 SMP PREEMPT_DYNAMIC Wed Jun 7 08:47:23 CEST 2023 x86_64
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System Capabilities TLV (7), length 4
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System Capabilities [Bridge, WLAN AP, Router, Station Only] (0x009c)
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Enabled Capabilities [Station Only] (0x0080)
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Management Address TLV (8), length 12
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Management Address length 5, AFI IPv4 (1): 10.0.1.1
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Interface Index Interface Numbering (2): 2
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Management Address TLV (8), length 24
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Management Address length 17, AFI IPv6 (2): 2001:db8::1
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Interface Index Interface Numbering (2): 3
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Port Description TLV (4), length 4: eth0
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Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
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Link aggregation Subtype (3)
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aggregation status [supported], aggregation port ID 0
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Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
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MAC/PHY configuration/status Subtype (1)
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autonegotiation [none] (0x00)
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PMD autoneg capability [unknown] (0x8000)
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MAU type Unknown (0x0000)
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End TLV (0), length 0
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^C
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1 packet captured
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2 packets received by filter
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0 packets dropped by kernel
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linux-pc:#
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```
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The LLDP service can be disabled using the following commands.
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```
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admin@infix-c0-ff-ee:/> configure
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admin@infix-c0-ff-ee:/config/> no lldp
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admin@infix-c0-ff-ee:/config/> leave
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admin@infix-c0-ff-ee:/>
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```
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## mDNS-SD
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DNS-SD/mDNS-SD can be used to discover Infix devices and services. By
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default, Infix use the `.local` domain for advertising services. Some
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networks use `.lan` instead, so this configurable:
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```
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admin@infix-c0-ff-ee:/> configure
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admin@infix-c0-ff-ee:/config/> edit mdns
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admin@infix-c0-ff-ee:/config/mdns/> set domain lan
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```
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Other available settings include limiting the interfaces mDNS responder
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acts on:
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```
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admin@infix-c0-ff-ee:/config/> set interfaces allow e1
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```
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or
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```
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admin@infix-c0-ff-ee:/config/> set interfaces deny wan
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```
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The `allow` and `deny` settings are complementary, `deny` always wins.
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----
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In Linux, tools such as *avahi-browse* or *mdns-scan*[^2] can be used to
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search for devices advertising their services via mDNS.
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```
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linux-pc:# avahi-browse -ar
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+ tap0 IPv6 infix-c0-ff-ee SFTP File Transfer local
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+ tap0 IPv4 infix-c0-ff-ee SFTP File Transfer local
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+ tap0 IPv6 infix-c0-ff-ee SSH Remote Terminal local
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+ tap0 IPv4 infix-c0-ff-ee SSH Remote Terminal local
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= tap0 IPv4 infix-c0-ff-ee SFTP File Transfer local
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hostname = [infix-c0-ff-ee.local]
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address = [10.0.1.1]
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port = [22]
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txt = []
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= tap0 IPv4 infix-c0-ff-ee SSH Remote Terminal local
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hostname = [infix-c0-ff-ee.local]
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address = [10.0.1.1]
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port = [22]
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txt = []
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= tap0 IPv6 infix-c0-ff-ee SFTP File Transfer local
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hostname = [infix-c0-ff-ee.local]
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address = [fe80::ff:fec0:ffed]
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port = [22]
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txt = []
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= tap0 IPv6 infix-c0-ff-ee SSH Remote Terminal local
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hostname = [infix-c0-ff-ee.local]
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address = [fe80::ff:fec0:ffed]
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port = [22]
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txt = []
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^C
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linux-pc:#
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```
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> [!TIP]
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> The `-t` option is also very useful, it stops browsing automatically
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> when a "more or less complete list" has been printed. However, some
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> devices on the LAN may be in deep sleep so run the command again if
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> you cannot find the device you are looking for.
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Additionally, *avahi-resolve-host-name* can be used to verify domain
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name mappings for IP addresses. By default, it translates from IPv4
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addresses. This function allows users to confirm that addresses are
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mapped correctly.
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```
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linux-pc:# avahi-resolve-host-name infix-c0-ff-ee.local
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infix-c0-ff-ee.local 10.0.1.1
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linux-pc:#
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```
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Thanks to mDNS we can use the advertised name instead of the IP
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address for operations like `ping` and `ssh` as shown below:
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```
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linux-pc:# ping infix-c0-ff-ee.local -c 3
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PING infix-c0-ff-ee.local (10.0.1.1) 56(84) bytes of data.
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64 bytes from 10.0.1.1: icmp_seq=1 ttl=64 time=0.852 ms
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64 bytes from 10.0.1.1: icmp_seq=2 ttl=64 time=1.12 ms
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64 bytes from 10.0.1.1: icmp_seq=3 ttl=64 time=1.35 ms
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--- infix-c0-ff-ee.local ping statistics ---
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3 packets transmitted, 3 received, 0% packet loss, time 2003ms
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rtt min/avg/max/mdev = 0.852/1.105/1.348/0.202 ms
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linux-pc:# ssh admin@infix-c0-ff-ee.local
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(admin@infix-c0-ff-ee.local) Password:
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.-------.
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| . . | Infix -- a Network Operating System
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|-. v .-| https://kernelkit.org
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'-'---'-
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Run the command 'cli' for interactive OAM
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linux-pc:#
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```
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To disable mDNS/mDNS-SD, type the commands:
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```
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admin@infix-c0-ff-ee:/> configure
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admin@infix-c0-ff-ee:/config/> no mdns
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admin@infix-c0-ff-ee:/config/> leave
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```
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### Human-Friendly Hostname Alias
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Each Infix deviuce advertise itself as *infix.local*, in addition to its
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full hostname (e.g., *infix-c0-ff-ee.local* or *foo.local*). This alias
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works seamlessly on a network with a single Infix device, and makes it
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easy to connect when the exact hostname is not known in advance. The
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examples below show how the alias can be used for actions such as
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pinging or establishing an SSH connection:
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```
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linux-pc:# ping infix.local -c 3
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PING infix.local (10.0.1.1) 56(84) bytes of data.
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64 bytes from 10.0.1.1: icmp_seq=1 ttl=64 time=0.751 ms
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64 bytes from 10.0.1.1: icmp_seq=2 ttl=64 time=2.28 ms
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64 bytes from 10.0.1.1: icmp_seq=3 ttl=64 time=1.42 ms
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--- infix.local ping statistics ---
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3 packets transmitted, 3 received, 0% packet loss, time 2003ms
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rtt min/avg/max/mdev = 0.751/1.482/2.281/0.626 ms
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linux-pc:# ssh admin@infix.local
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(admin@infix.local) Password:
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.-------.
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| . . | Infix -- a Network Operating System
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|-. v .-| https://kernelkit.org
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'-'---'-
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Run the command 'cli' for interactive OAM
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admin@infix-c0-ff-ee:~$
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```
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When multiple Infix devices are present on the LAN the alias will not
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uniquely identify a device; *infix.local* will refer to any of the
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Infix devices, likely the one that first appeared.
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> [!NOTE]
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> When multiple Infix devices are present on the LAN, use the full name,
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> e.g., *infix-c0-ff-ee.local* or *foo.local* rather than the alias
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> *infix.local* to deterministically connect to the device.
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### Browse Network Using *network.local*
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Another mDNS alias that all Infix devices advertise is *network.local*.
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This is a web service which basically runs `avahi-browse` and displays a
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table of other Infix devices and their services.
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With multiple Infix devices on the LAN, one will take the role of your
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portal to access all others, if it goes down another takes its place.
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To disable the netbrowse service, and the *network.local* alias, the
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following commands can be used:
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```
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admin@infix-c0-ff-ee:/> configure
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admin@infix-c0-ff-ee:/config/> edit web
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admin@infix-c0-ff-ee:/config/web/> no netbrowse
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admin@infix-c0-ff-ee:/config/web/> leave
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```
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[^1]: E.g., [lldpd](https://github.com/lldp/lldpd) which includes the
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*lldpcli* too, handy to sniff and display LLDP packets.
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[^2]: [mdns-scan](http://0pointer.de/lennart/projects/mdns-scan/): a
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tool for scanning for mDNS/DNS-SD services on the local network.
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