README.md

   1 lldpd: implementation of IEEE 802.1ab (LLDP)
   2 ============================================
   3
   4 ![Build Status](https://github.com/lldpd/lldpd/workflows/CI/badge.svg)
   5
   6   https://lldpd.github.io/
   7
   8 Features
   9 --------
  10
  11 LLDP (Link Layer Discovery Protocol) is an industry standard protocol
  12 designed to supplant proprietary Link-Layer protocols such as
  13 Extreme's EDP (Extreme Discovery Protocol) and CDP (Cisco Discovery
  14 Protocol). The goal of LLDP is to provide an inter-vendor compatible
  15 mechanism to deliver Link-Layer notifications to adjacent network
  16 devices.
  17
  18 lldpd implements both reception and sending. It also implements an
  19 SNMP subagent for net-snmp to get local and remote LLDP
  20 information. The LLDP-MIB is partially implemented but the most useful
  21 tables are here. lldpd also partially implements LLDP-MED.
  22
  23 lldpd supports bridge, vlan and bonding.
  24
  25 The following OS are supported:
  26
  27  * FreeBSD
  28  * GNU/Linux
  29  * macOS
  30  * NetBSD
  31  * OpenBSD
  32  * Solaris
  33
  34 Windows is not supported but you can use
  35 [WinLLDPService](https://github.com/raspi/WinLLDPService/) as a
  36 transmit-only agent.
  37
  38 Installation
  39 ------------
  40
  41 For general instructions [prefer the
  42 website](https://lldpd.github.io/installation.html),
  43 including building from released tarballs.
  44
  45 To compile lldpd from Git, use the following commands:
  46
  47     ./autogen.sh
  48     ./configure
  49     make
  50     sudo make install
  51
  52 lldpd uses privilege separation to increase its security. Two
  53 processes, one running as root and doing minimal stuff and the other
  54 running as an unprivileged user into a chroot doing most of the stuff,
  55 are cooperating. You need to create a user called `_lldpd` in a group
  56 `_lldpd` (this can be change with `./configure`). You also need to
  57 create an empty directory `/usr/local/var/run/lldpd` (it needs to be
  58 owned by root, not `_lldpd`!). If you get fuzzy timestamps from
  59 syslog, copy `/etc/locatime` into the chroot.
  60
  61 `lldpcli` lets one query information collected through the command
  62 line. If you don't want to run it as root, just install it setuid or
  63 setgid `_lldpd`.
  64
  65 Installation (macOS)
  66 -----------------------
  67
  68 The same procedure as above applies for macOS. However, there are
  69 simpler alternatives:
  70
  71  1. Use [Homebrew](https://brew.sh):
  72
  73         brew install lldpd
  74         # Or, for the latest version:
  75         brew install https://raw.github.com/lldpd/lldpd/master/osx/lldpd.rb
  76
  77  2. Build an macOS installer package which should work on the same
  78     version of macOS:
  79
  80         mkdir build && cd build
  81         ../configure --prefix=/usr/local --localstatedir=/var --sysconfdir=/private/etc --with-embedded-libevent \
  82             --without-snmp
  83         make -C osx pkg
  84
  85     If you want to compile for an older version of macOS, you need
  86     to find the right SDK and issues commands like those:
  87
  88         SDK=/Developer/SDKs/MacOSX10.6.sdk
  89         mkdir build && cd build
  90         ../configure --prefix=/usr/local --localstatedir=/var --sysconfdir=/private/etc --with-embedded-libevent \
  91            --without-snmp \
  92            CFLAGS="-mmacosx-version-min=10.6 -isysroot $SDK" \
  93            LDFLAGS="-mmacosx-version-min=10.6 -isysroot $SDK"
  94         make -C osx pkg
  95
  96     With recent SDK, you don't need to specify an alternate SDK. They
  97     are organized in a way that should enable compatibility with older
  98     versions of OSX:
  99
 100         mkdir build && cd build
 101         ../configure --prefix=/usr/local --localstatedir=/var --sysconfdir=/private/etc --with-embedded-libevent \
 102            --without-snmp \
 103            CFLAGS="-mmacosx-version-min=10.9" \
 104            LDFLAGS="-mmacosx-version-min=10.9"
 105         make -C osx pkg
 106
 107     You can check with `otool -l` that you got what you expected in
 108     term of supported versions.
 109
 110 If you don't follow the above procedures, you will have to create the
 111 user/group `_lldpd`. Have a look at how this is done in
 112 `osx/scripts/postinstall`.
 113
 114 Installation (Android)
 115 ----------------------
 116
 117 You need to download [Android NDK][]. Once unpacked, go inside the
 118 unpacked directory and select a toolchain, a target, and an API level:
 119
 120     export TOOLCHAIN=$PWD/toolchains/llvm/prebuilt/linux-x86_64
 121     export TARGET=aarch64-linux-android
 122     export API=24
 123
 124 You need to export a bunch of variables:
 125
 126     export AR=$TOOLCHAIN/bin/llvm-ar
 127     export CC=$TOOLCHAIN/bin/$TARGET$API-clang
 128     export CXX=$TOOLCHAIN/bin/$TARGET$API-clang++
 129     export LD=$TOOLCHAIN/bin/ld
 130     export RANLIB=$TOOLCHAIN/bin/llvm-ranlib
 131     export STRIP=$TOOLCHAIN/bin/llvm-strip
 132     export AS=$CC
 133
 134 Then, you can build `lldpd` with the following commands:
 135
 136     mkdir build && cd build
 137     ../configure \
 138         --host=$TARGET \
 139         --with-sysroot=$TOOLCHAIN/sysroot \
 140         --prefix=/system \
 141         --sbindir=/system/bin \
 142         --runstatedir=/data/data/lldpd \
 143         --with-privsep-user=root \
 144         --with-privsep-group=root \
 145         PKG_CONFIG=/bin/false
 146     make
 147     make install DESTDIR=$PWD/install
 148
 149 Then, copy `install/system/bin/*` to `/system/bin` on the target
 150 system and `install/system/lib/*.so*` to `/system/lib` on the target
 151 system. You may need to create `/data/data/lldpd` as well.
 152
 153 [Android NDK]: https://developer.android.com/ndk
 154
 155 Usage
 156 -----
 157
 158 lldpd also implements CDP (Cisco Discovery Protocol), FDP (Foundry
 159 Discovery Protocol), SONMP (Nortel Discovery Protocol) and EDP
 160 (Extreme Discovery Protocol). However, recent versions of IOS should
 161 support LLDP and most Extreme stuff support LLDP. When a EDP, CDP or
 162 SONMP frame is received on a given interface, lldpd starts sending
 163 EDP, CDP, FDP or SONMP frame on this interface. Informations collected
 164 through EDP/CDP/FDP/SONMP are integrated with other informations and
 165 can be queried with `lldpcli` or through SNMP.
 166
 167 More information:
 168  * http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol
 169  * http://standards.ieee.org/getieee802/download/802.1AB-2005.pdf
 170  * http://wiki.wireshark.org/LinkLayerDiscoveryProtocol
 171
 172 Compatibility with older kernels
 173 --------------------------------
 174
 175 If you have a kernel older than Linux 2.6.39, you need to compile
 176 lldpd with `--enable-oldies` to enable some compatibility functions:
 177 otherwise, lldpd will only rely on Netlink to receive bridge, bond and
 178 VLAN information.
 179
 180 For bonding, you need 2.6.24 (in previous version, PACKET_ORIGDEV
 181 affected only non multicast packets). See:
 182
 183  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=80feaacb8a6400a9540a961b6743c69a5896b937
 184  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8032b46489e50ef8f3992159abd0349b5b8e476c
 185
 186 Otherwise, a packet received on a bond will be affected to all
 187 interfaces of the bond. In this case, lldpd will affect a received
 188 randomly to one of the interface (so a neighbor may be affected to the
 189 wrong interface).
 190
 191 On 2.6.27, we are able to receive packets on real interface for enslaved
 192 devices. This allows one to get neighbor information on active/backup
 193 bonds. Without the 2.6.27, lldpd won't receive any information on
 194 inactive slaves. Here are the patchs (thanks to Joe Eykholt):
 195
 196  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0d7a3681232f545c6a59f77e60f7667673ef0e93
 197  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cc9bd5cebc0825e0fabc0186ab85806a0891104f
 198  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f982307f22db96201e41540295f24e8dcc10c78f
 199
 200 On FreeBSD, only a recent 9 kernel (9.1 or more recent) will allow to
 201 send LLDP frames on enslaved devices. See this bug report for more
 202 information:
 203
 204  * http://www.freebsd.org/cgi/query-pr.cgi?pr=138620
 205
 206 Some devices (notably Cisco IOS) send frames tagged with the native
 207 VLAN while they should send them untagged. If your network card does
 208 not support accelerated VLAN, you will receive those frames as long as
 209 the corresponding interface exists (see below). However, if your
 210 network card handles VLAN encapsulation/decapsulation (check with
 211 `ethtool -k`), you need a recent kernel to be able to receive those
 212 frames without listening on all available VLAN. Starting from Linux
 213 2.6.27, lldpd is able to capture VLAN frames when VLAN acceleration is
 214 supported by the network card. Here is the patch:
 215
 216  * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bc1d0411b804ad190cdadabac48a10067f17b9e6
 217
 218 On some other versions, frames are sent on VLAN 1. If this is not the
 219 native VLAN and if your network card support accelerated VLAN, you
 220 need to subscribe to this VLAN as well. The Linux kernel does not
 221 provide any interface for this. The easiest way is to create the VLAN
 222 for each port:
 223
 224     ip link add link eth0 name eth0.1 type vlan id 1
 225     ip link set up dev eth0.1
 226
 227 You can check both cases using tcpdump:
 228
 229     tcpdump -epni eth0 ether host 01:80:c2:00:00:0e
 230     tcpdump -eni eth0 ether host 01:80:c2:00:00:0e
 231
 232 If the first command does not display received LLDP packets but the
 233 second one does, LLDP packets are likely encapsulated into a VLAN:
 234
 235     10:54:06.431154 f0:29:29:1d:7c:01 > 01:80:c2:00:00:0e, ethertype 802.1Q (0x8100), length 363: vlan 1, p 7, ethertype LLDP, LLDP, name SW-APP-D07.VTY, length 345
 236
 237 In this case, just create VLAN 1 will fix the situation. There are
 238 other solutions:
 239
 240  1. Disable VLAN acceleration on the receive side (`ethtool -K eth0
 241     rxvlan off`) but this may or may not work. Check if there are
 242     similar properties that could apply with `ethtool -k eth0`.
 243  2. Put the interface in promiscuous mode with `ip link set
 244     promisc on dev eth0`.
 245
 246 The last solution can be done directly by `lldpd` (on Linux only) by
 247 using the option `configure system interface promiscuous`.
 248
 249 On modern networks, the performance impact should be nonexistent.
 250
 251 Development
 252 -----------
 253
 254 During development, you may want to execute lldpd at its current
 255 location instead of doing `make install`. The correct way to do this is
 256 to issue the following command:
 257
 258     sudo libtool execute src/daemon/lldpd -L $PWD/src/client/lldpcli -d
 259
 260 You can append any further arguments. If lldpd is unable to find
 261 `lldpcli` it will start in an unconfigured mode and won't send or
 262 accept LLDP frames.
 263
 264 You can use [afl](http://lcamtuf.coredump.cx/afl/) to test some
 265 aspects of lldpd. To test frame decoding, you can do something like
 266 that:
 267
 268     export AFL_USE_ASAN=1 # only on 32bit arch
 269     ./configure CC=afl-gcc
 270     make clean check
 271     cd tests
 272     mkdir inputs
 273     mv *.pcap inputs
 274     afl-fuzz -i inputs -o outputs ./decode @@
 275
 276 There is a general test suite with `make check`. It's also possible to
 277 run integration tests. They need [py.test](http://pytest.org/latest/)
 278 and rely on Linux containers to be executed.
 279
 280 To enable code coverage, use:
 281
 282     ../configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var \
 283                  --enable-sanitizers --enable-gcov --with-snmp \
 284                  CFLAGS="-O0 -g"
 285     make
 286     make check
 287     # maybe, run integration tests
 288     lcov --base-directory $PWD/src/lib \
 289          --directory src --capture --output-file gcov.info
 290     genhtml gcov.info --output-directory coverage
 291
 292 Embedding
 293 ---------
 294
 295 To embed lldpd into an existing system, there are two point of entries:
 296
 297  1. If your system does not use standard Linux interface, you can
 298     support additional interfaces by implementing the appropriate
 299     `struct lldpd_ops`. You can look at
 300     `src/daemon/interfaces-linux.c` for examples. Also, have a look at
 301     `interfaces_update()` which is responsible for discovering and
 302     registering interfaces.
 303
 304  2. `lldpcli` provides a convenient way to query `lldpd`. It also
 305     comes with various outputs, including XML which allows one to
 306     parse its output for integration and automation purpose. Another
 307     way is to use SNMP support. A third way is to write your own
 308     controller using `liblldpctl.so`. Its API is described in
 309     `src/lib/lldpctl.h`. The custom binary protocol between
 310     `liblldpctl.so` and `lldpd` is not stable. Therefore, the library
 311     should always be shipped with `lldpd`. On the other hand, programs
 312     using `liblldpctl.so` can rely on the classic ABI rules.
 313
 314 Troubleshooting
 315 ---------------
 316
 317 You can use `tcpdump` to look after the packets received and send by
 318 `lldpd`. To look after LLDPU, use:
 319
 320     tcpdump -s0 -vv -pni eth0 ether dst 01:80:c2:00:00:0e
 321
 322 Intel X710 cards may handle LLDP themselves, intercepting any incoming
 323 packets. If you don't see anything through `tcpdump`, check if you
 324 have such a card (with `lspci`) and stop the embedded LLDP daemon:
 325
 326     for f in /sys/kernel/debug/i40e/*/command; do
 327         echo lldp stop > $f
 328     done
 329
 330 License
 331 -------
 332
 333 lldpd is distributed under the ISC license:
 334
 335  > Permission to use, copy, modify, and/or distribute this software for any
 336  > purpose with or without fee is hereby granted, provided that the above
 337  > copyright notice and this permission notice appear in all copies.
 338  >
 339  > THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 340  > WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 341  > MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 342  > ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 343  > WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 344  > ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 345  > OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 346
 347 Also, `lldpcli` will be linked to GNU Readline (which is GPL licensed)
 348 if available. To avoid this, use `--without-readline` as a configure
 349 option.