# lldpd: implementation of IEEE 802.1ab (LLDP) ![Build Status](https://github.com/lldpd/lldpd/workflows/CI/badge.svg) https://lldpd.github.io/ ## Features LLDP (Link Layer Discovery Protocol) is an industry standard protocol designed to supplant proprietary Link-Layer protocols such as Extreme's EDP (Extreme Discovery Protocol) and CDP (Cisco Discovery Protocol). The goal of LLDP is to provide an inter-vendor compatible mechanism to deliver Link-Layer notifications to adjacent network devices. lldpd implements both reception and sending. It also implements an SNMP subagent for net-snmp to get local and remote LLDP information. The LLDP-MIB is partially implemented but the most useful tables are here. lldpd also partially implements LLDP-MED. lldpd supports bridge, vlan and bonding. The following OS are supported: * FreeBSD * GNU/Linux * macOS * NetBSD * OpenBSD * Solaris Windows is not supported but you can use [WinLLDPService](https://github.com/raspi/WinLLDPService/) as a transmit-only agent. ## Installation For general instructions [prefer the website](https://lldpd.github.io/installation.html), including building from released tarballs. To compile lldpd from Git, use the following commands: ./autogen.sh ./configure make sudo make install lldpd uses privilege separation to increase its security. Two processes, one running as root and doing minimal stuff and the other running as an unprivileged user into a chroot doing most of the stuff, are cooperating. You need to create a user called `_lldpd` in a group `_lldpd` (this can be change with `./configure`). You also need to create an empty directory `/usr/local/var/run/lldpd` (it needs to be owned by root, not `_lldpd`!). If you get fuzzy timestamps from syslog, copy `/etc/locatime` into the chroot. `lldpcli` lets one query information collected through the command line. If you don't want to run it as root, just install it setuid or setgid `_lldpd`. ## Installation (Docker) You can use Docker to run `lldpd`: docker run --rm --net=host --uts=host \ -v /etc/os-release:/etc/os-release \ --cap-add=NET_RAW --cap-add=NET_ADMIN \ --name lldpd \ ghcr.io/lldpd/lldpd:latest In place of `latest` which provides you with the latest stable version, you may use `1`, `1.0`, `1.0.12` to match specific versions, or `master` to get the development version. To execute `lldpcli`, use: docker exec lldpd lldpcli show neighbors Or to get the command-line: docker exec -it lldpd lldpcli ## Installation (macOS) The same procedure as above applies for macOS. However, there are simpler alternatives: 1. Use [Homebrew](https://brew.sh): brew install lldpd # Or, for the latest version: brew install https://raw.github.com/lldpd/lldpd/master/osx/lldpd.rb 2. Build an OS X installer package which should work on the same version of OS X (it is important to use a separate build directory): mkdir build && cd build ../configure --prefix=/usr/local --localstatedir=/var --sysconfdir=/private/etc --with-embedded-libevent \ --without-snmp make -C osx pkg If you want to compile for an older version of macOS, you need commands like those: mkdir build && cd build ../configure --prefix=/usr/local --localstatedir=/var --sysconfdir=/private/etc --with-embedded-libevent \ --without-snmp \ CFLAGS="-mmacosx-version-min=11.1" \ LDFLAGS="-mmacosx-version-min=11.1" make -C osx pkg You can check with `otool -l` that you got what you expected in term of supported versions. If you are running on ARM64, you can configure a binary supporting both architectures by adding `ARCHS="arm64 x86_64"` to the arguments of the `make` command. If you don't follow the above procedures, you will have to create the user/group `_lldpd`. Have a look at how this is done in `osx/scripts/postinstall`. ## Installation (Android) 1. Don't clone the repo or download the master branch from GitHub. Instead, download the official release from the website [https://lldpd.github.io/](https://lldpd.github.io/installation.html#install-from-source). Unpack into a working directory. 2. Download the [Android NDK](https://developer.android.com/ndk/downloads#stable-downloads) (version 22 or later). Unpack into a working directory next to the `lldpd` directory. 3. Install `automake`, `libtool`, and `pkg-config`. (`sudo apt-get install automake libtool pkg-config`) 4. In the root of the `lldpd` directory, make a `compile.sh` file containing this script: ```sh export TOOLCHAIN=$PWD/android-ndk/toolchains/llvm/prebuilt/linux-x86_64 export TARGET=armv7a-linux-androideabi export API=30 # DO NOT TOUCH BELOW export AR=$TOOLCHAIN/bin/llvm-ar export CC=$TOOLCHAIN/bin/$TARGET$API-clang export CXX=$TOOLCHAIN/bin/$TARGET$API-clang++ export LD=$TOOLCHAIN/bin/ld export RANLIB=$TOOLCHAIN/bin/llvm-ranlib export STRIP=$TOOLCHAIN/bin/llvm-strip export AS=$CC ./autogen.sh mkdir -p build && cd build ../configure \ --host=$TARGET \ --with-sysroot=$TOOLCHAIN/sysroot \ --prefix=/system \ --sbindir=/system/bin \ --runstatedir=/data/data/lldpd \ --with-privsep-user=root \ --with-privsep-group=root \ PKG_CONFIG=/bin/false make make install DESTDIR=$PWD/install ``` 5. In the **Android NDK** directory, locate the `toolchains/llvm/prebuilt/linux-x86_64` directory and change the `TOOLCHAIN` variable of the above script to match the path where the `linux-x86_64` directory resides. ```sh export TOOLCHAIN=$PWD/android-ndk-r22b-linux-x86_64/android-ndk-r22b/toolchains/llvm/prebuilt/linux-x86_64 ``` 6. Determine the CPU architecture target (`adb shell getprop ro.product.cpu.abi`). Change the `TARGET` variable in the above script to match the target architecture. The target name will not exactly match the output of the `adb` command as there will be a trailing suffix to the target name, so look in the `linux-x86_64/bin` directory for the `clang` file that starts with the CPU architecture target. Don't include the API version in the target name. ```sh $ adb shell getprop ro.product.cpu.abi armeabi-v7a ``` ```sh linux-x86_64/bin$ ls *-clang aarch64-linux-android21-clang armv7a-linux-androideabi23-clang i686-linux-android26-clang aarch64-linux-android22-clang armv7a-linux-androideabi24-clang i686-linux-android27-clang aarch64-linux-android23-clang armv7a-linux-androideabi26-clang i686-linux-android28-clang aarch64-linux-android24-clang armv7a-linux-androideabi27-clang i686-linux-android29-clang aarch64-linux-android26-clang armv7a-linux-androideabi28-clang i686-linux-android30-clang aarch64-linux-android27-clang armv7a-linux-androideabi29-clang x86_64-linux-android21-clang aarch64-linux-android28-clang armv7a-linux-androideabi30-clang x86_64-linux-android22-clang aarch64-linux-android29-clang i686-linux-android16-clang x86_64-linux-android23-clang aarch64-linux-android30-clang i686-linux-android17-clang x86_64-linux-android24-clang armv7a-linux-androideabi16-clang i686-linux-android18-clang x86_64-linux-android26-clang armv7a-linux-androideabi17-clang i686-linux-android19-clang x86_64-linux-android27-clang armv7a-linux-androideabi18-clang i686-linux-android21-clang x86_64-linux-android28-clang armv7a-linux-androideabi19-clang i686-linux-android22-clang x86_64-linux-android29-clang armv7a-linux-androideabi21-clang i686-linux-android23-clang x86_64-linux-android30-clang armv7a-linux-androideabi22-clang i686-linux-android24-clang ``` ```sh export TARGET=armv7a-linux-androideabi ``` 7. Set the `API` variable in the script above to your target API version. Check in the same `linux-x86_64/bin` to ensure the API you are targeting has a supported `clang` file for that CPU architecture and version. As of this writing, there is support for API `21-30` included for all architectures and some CPU architectures supported back to version `16`. ```sh export API=30 ``` 8. Run the compile script (`./compile.sh`). 9. Copy the `./bin/*` and `./lib/*.so` files from `lldpd/build/install/system` to the target system (`./bin/*` to `/system/bin`, `./lib/*.so` to `/system/lib64`): ```sh # Push files to target cd build/install/system adb shell mkdir -p /sdcard/Download/lldpd/bin adb push bin/lldpcli /sdcard/Download/lldpd/bin/lldpcli adb push bin/lldpd /sdcard/Download/lldpd/bin/lldpd adb shell mkdir -p /sdcard/Download/lldpd/lib64 adb push lib/liblldpctl.so /sdcard/Download/lldpd/lib64/liblldpctl.so # Enter target shell and move files adb shell # Run as root for all commands $ su # Make /system writeable $ mount -o rw,remount /system $ mv /sdcard/Download/lldpd/bin/lldpcli /system/bin/lldpcli $ chmod 755 /system/bin/lldpcli $ chown root:shell /system/bin/lldpcli $ mv /sdcard/Download/lldpd/bin/lldpd /system/bin/lldpd $ chmod 755 /system/bin/lldpd $ chown root:shell /system/bin/lldpd # $ touch /system/bin/lldpctl # $ chmod 755 /system/bin/lldpctl # $ chown root:shell /system/bin/lldpctl $ mv /sdcard/Download/lldpd/lib64/liblldpctl.so /system/lib64/liblldpctl.so $ chmod 644 /system/lib64/liblldpctl.so $ chown root:root /system/lib64/liblldpctl.so # Make /system readonly again $ mount -o ro,remount /system # Might not be necessary on some systems $ mkdir /data/data/lldpd $ chmod 700 /data/data/lldpd $ chown shell:shell /data/data/lldpd # Clean up $ rm -rf /sdcard/Download/lldpd ``` ## Usage lldpd also implements CDP (Cisco Discovery Protocol), FDP (Foundry Discovery Protocol), SONMP (Nortel Discovery Protocol) and EDP (Extreme Discovery Protocol). However, recent versions of IOS should support LLDP and most Extreme stuff support LLDP. When a EDP, CDP or SONMP frame is received on a given interface, lldpd starts sending EDP, CDP, FDP or SONMP frame on this interface. Informations collected through EDP/CDP/FDP/SONMP are integrated with other informations and can be queried with `lldpcli` or through SNMP. More information: * http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol * http://standards.ieee.org/getieee802/download/802.1AB-2005.pdf * https://gitlab.com/wireshark/wireshark/-/wikis/LinkLayerDiscoveryProtocol ## Compatibility with older kernels If you have a kernel older than Linux 2.6.39, you need to compile lldpd with `--enable-oldies` to enable some compatibility functions: otherwise, lldpd will only rely on Netlink to receive bridge, bond and VLAN information. For bonding, you need 2.6.24 (in previous version, PACKET_ORIGDEV affected only non multicast packets). See: * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=80feaacb8a6400a9540a961b6743c69a5896b937 * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8032b46489e50ef8f3992159abd0349b5b8e476c Otherwise, a packet received on a bond will be affected to all interfaces of the bond. In this case, lldpd will affect a received randomly to one of the interface (so a neighbor may be affected to the wrong interface). On 2.6.27, we are able to receive packets on real interface for enslaved devices. This allows one to get neighbor information on active/backup bonds. Without the 2.6.27, lldpd won't receive any information on inactive slaves. Here are the patchs (thanks to Joe Eykholt): * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0d7a3681232f545c6a59f77e60f7667673ef0e93 * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cc9bd5cebc0825e0fabc0186ab85806a0891104f * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f982307f22db96201e41540295f24e8dcc10c78f On FreeBSD, only a recent 9 kernel (9.1 or more recent) will allow to send LLDP frames on enslaved devices. See this bug report for more information: * http://www.freebsd.org/cgi/query-pr.cgi?pr=138620 Some devices (notably Cisco IOS) send frames tagged with the native VLAN while they should send them untagged. If your network card does not support accelerated VLAN, you will receive those frames as long as the corresponding interface exists (see below). However, if your network card handles VLAN encapsulation/decapsulation (check with `ethtool -k`), you need a recent kernel to be able to receive those frames without listening on all available VLAN. Starting from Linux 2.6.27, lldpd is able to capture VLAN frames when VLAN acceleration is supported by the network card. Here is the patch: * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bc1d0411b804ad190cdadabac48a10067f17b9e6 On some other versions, frames are sent on VLAN 1. If this is not the native VLAN and if your network card support accelerated VLAN, you need to subscribe to this VLAN as well. The Linux kernel does not provide any interface for this. The easiest way is to create the VLAN for each port: ip link add link eth0 name eth0.1 type vlan id 1 ip link set up dev eth0.1 You can check both cases using tcpdump: tcpdump -epni eth0 ether host 01:80:c2:00:00:0e tcpdump -eni eth0 ether host 01:80:c2:00:00:0e If the first command does not display received LLDP packets but the second one does, LLDP packets are likely encapsulated into a VLAN: 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 In this case, just create VLAN 1 will fix the situation. There are other solutions: 1. Disable VLAN acceleration on the receive side (`ethtool -K eth0 rxvlan off`) but this may or may not work. Check if there are similar properties that could apply with `ethtool -k eth0`. 2. Put the interface in promiscuous mode with `ip link set promisc on dev eth0`. The last solution can be done directly by `lldpd` (on Linux only) by using the option `configure system interface promiscuous`. On modern networks, the performance impact should be nonexistent. ## Development During development, you may want to execute lldpd at its current location instead of doing `make install`. The correct way to do this is to issue the following command: sudo libtool execute src/daemon/lldpd -L $PWD/src/client/lldpcli -d You can append any further arguments. If lldpd is unable to find `lldpcli` it will start in an unconfigured mode and won't send or accept LLDP frames. There is a general test suite with `make check`. It's also possible to run integration tests. They need [pytest](http://pytest.org/latest/) and rely on Linux containers to be executed. To enable code coverage, use: ../configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var \ --enable-sanitizers --enable-gcov --with-snmp \ CFLAGS="-O0 -g" make make check # maybe, run integration tests lcov --base-directory $PWD/src/lib \ --directory src --capture --output-file gcov.info genhtml gcov.info --output-directory coverage ## Fuzzing ### With [libfuzzer](https://llvm.org/docs/LibFuzzer.html) Using address sanitizer: ```bash export CC=clang export CFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only -fsanitize=address -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link" export LIB_FUZZING_ENGINE="-fsanitize=fuzzer" ``` Using undefined-behaviour sanitizer: ```bash export CC=clang export CFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only -fsanitize=array-bounds,bool,builtin,enum,float-divide-by-zero,function,integer-divide-by-zero,null,object-size,return,returns-nonnull-attribute,shift,signed-integer-overflow,unsigned-integer-overflow,unreachable,vla-bound,vptr -fno-sanitize-recover=array-bounds,bool,builtin,enum,float-divide-by-zero,function,integer-divide-by-zero,null,object-size,return,returns-nonnull-attribute,shift,signed-integer-overflow,unreachable,vla-bound,vptr -fsanitize=fuzzer-no-link" export LIB_FUZZING_ENGINE="-fsanitize=fuzzer" ``` Using memory sanitizer: ```bash export CC=clang export CFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only -fsanitize=memory -fsanitize-memory-track-origins -fsanitize=fuzzer-no-link" export LIB_FUZZING_ENGINE="-fsanitize=fuzzer" ``` Build and run: ``` ./configure --disable-shared --enable-pie --enable-fuzzer=$LIB_FUZZING_ENGINE make cd tests/ ./fuzz_cdp fuzzing_seed_corpus/fuzz_cdp_seed_corpus ./fuzz_edp fuzzing_seed_corpus/fuzz_edp_seed_corpus ./fuzz_lldp fuzzing_seed_corpus/fuzz_lldp_seed_corpus ./fuzz_sonmp fuzzing_seed_corpus/fuzz_sonmp_seed_corpus ``` ### With [AFL++](https://aflplus.plus) You can use AFL++ to test some other aspects of lldpd. To test frame decoding: ```bash export CC=afl-clang-fast ./configure --disable-shared --enable-pie make clean check cd tests mkdir inputs mv *.pcap inputs afl-fuzz -i inputs -o outputs ./decode @@ ``` ## Embedding To embed lldpd into an existing system, there are two point of entries: 1. If your system does not use standard Linux interface, you can support additional interfaces by implementing the appropriate `struct lldpd_ops`. You can look at `src/daemon/interfaces-linux.c` for examples. Also, have a look at `interfaces_update()` which is responsible for discovering and registering interfaces. 2. `lldpcli` provides a convenient way to query `lldpd`. It also comes with various outputs, including XML which allows one to parse its output for integration and automation purpose. Another way is to use SNMP support. A third way is to write your own controller using `liblldpctl.so`. Its API is described in `src/lib/lldpctl.h`. The custom binary protocol between `liblldpctl.so` and `lldpd` is not stable. Therefore, the library should always be shipped with `lldpd`. On the other hand, programs using `liblldpctl.so` can rely on the classic ABI rules. ## Troubleshooting You can use `tcpdump` to look after the packets received and send by `lldpd`. To look after LLDPU, use: tcpdump -s0 -vv -pni eth0 ether dst 01:80:c2:00:00:0e Intel X710 cards may handle LLDP themselves, intercepting any incoming packets. If you don't see anything through `tcpdump`, check if you have such a card (with `lspci`) and stop the embedded LLDP daemon: for f in /sys/kernel/debug/i40e/*/command; do echo lldp stop > $f done This may also apply to the `ice` (Intel E8xx cards) driver. These steps are not necessary with a recent version of `lldpd` (1.0.11+). ## License lldpd is distributed under the ISC license: > Permission to use, copy, modify, and/or distribute this software for any > purpose with or without fee is hereby granted, provided that the above > copyright notice and this permission notice appear in all copies. > > THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES > WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF > MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR > ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES > WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN > ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF > OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. Also, `lldpcli` will be linked to GNU Readline (which is GPL licensed) if available. To avoid this, use `--without-readline` as a configure option.