| Demonstrations of bindsnoop, the Linux eBPF/bcc version. |
| |
| This tool traces the kernel function performing socket binding and |
| print socket options set before the system call invocation that might |
| impact bind behavior and bound interface: |
| SOL_IP IP_FREEBIND F.... |
| SOL_IP IP_TRANSPARENT .T... |
| SOL_IP IP_BIND_ADDRESS_NO_PORT ..N.. |
| SOL_SOCKET SO_REUSEADDR ...R. |
| SOL_SOCKET SO_REUSEPORT ....r |
| |
| |
| # ./bindsnoop.py |
| Tracing binds ... Hit Ctrl-C to end |
| PID COMM PROT ADDR PORT OPTS IF |
| 3941081 test_bind_op TCP 192.168.1.102 0 F.N.. 0 |
| 3940194 dig TCP :: 62087 ..... 0 |
| 3940219 dig UDP :: 48665 ..... 0 |
| 3940893 Acceptor Thr TCP :: 35343 ...R. 0 |
| |
| The output shows four bind system calls: |
| two "test_bind_op" instances, one with IP_FREEBIND and IP_BIND_ADDRESS_NO_PORT |
| options, dig process called bind for TCP and UDP sockets, |
| and Acceptor called bind for TCP with SO_REUSEADDR option set. |
| |
| |
| The -t option prints a timestamp column |
| |
| # ./bindsnoop.py -t |
| TIME(s) PID COMM PROT ADDR PORT OPTS IF |
| 0.000000 3956801 dig TCP :: 49611 ..... 0 |
| 0.011045 3956822 dig UDP :: 56343 ..... 0 |
| 2.310629 3956498 test_bind_op TCP 192.168.1.102 39609 F...r 0 |
| |
| |
| The -U option prints a UID column: |
| |
| # ./bindsnoop.py -U |
| Tracing binds ... Hit Ctrl-C to end |
| UID PID COMM PROT ADDR PORT OPTS IF |
| 127072 3956498 test_bind_op TCP 192.168.1.102 44491 F...r 0 |
| 127072 3960261 Acceptor Thr TCP :: 48869 ...R. 0 |
| 0 3960729 Acceptor Thr TCP :: 44637 ...R. 0 |
| 0 3959075 chef-client UDP :: 61722 ..... 0 |
| |
| |
| The -u option filtering UID: |
| |
| # ./bindsnoop.py -Uu 0 |
| Tracing binds ... Hit Ctrl-C to end |
| UID PID COMM PROT ADDR PORT OPTS IF |
| 0 3966330 Acceptor Thr TCP :: 39319 ...R. 0 |
| 0 3968044 python3.7 TCP ::1 59371 ..... 0 |
| 0 10224 fetch TCP 0.0.0.0 42091 ...R. 0 |
| |
| |
| The --cgroupmap option filters based on a cgroup set. |
| It is meant to be used with an externally created map. |
| |
| # ./bindsnoop.py --cgroupmap /sys/fs/bpf/test01 |
| |
| For more details, see docs/special_filtering.md |
| |
| |
| In order to track heavy bind usage one can use --count option |
| # ./bindsnoop.py --count |
| Tracing binds ... Hit Ctrl-C to end |
| LADDR LPORT BINDS |
| 0.0.0.0 6771 4 |
| 0.0.0.0 4433 4 |
| 127.0.0.1 33665 1 |
| |
| |
| Usage message: |
| # ./bindsnoop.py -h |
| usage: bindsnoop.py [-h] [-t] [-w] [-p PID] [-P PORT] [-E] [-U] [-u UID] |
| [--count] [--cgroupmap CGROUPMAP] [--mntnsmap MNTNSMAP] |
| |
| Trace TCP binds |
| |
| optional arguments: |
| -h, --help show this help message and exit |
| -t, --timestamp include timestamp on output |
| -w, --wide wide column output (fits IPv6 addresses) |
| -p PID, --pid PID trace this PID only |
| -P PORT, --port PORT comma-separated list of ports to trace. |
| -E, --errors include errors in the output. |
| -U, --print-uid include UID on output |
| -u UID, --uid UID trace this UID only |
| --count count binds per src ip and port |
| --cgroupmap CGROUPMAP |
| trace cgroups in this BPF map only |
| |
| examples: |
| ./bindsnoop # trace all TCP bind()s |
| ./bindsnoop -t # include timestamps |
| ./bindsnoop -w # wider columns (fit IPv6) |
| ./bindsnoop -p 181 # only trace PID 181 |
| ./bindsnoop -P 80 # only trace port 80 |
| ./bindsnoop -P 80,81 # only trace port 80 and 81 |
| ./bindsnoop -U # include UID |
| ./bindsnoop -u 1000 # only trace UID 1000 |
| ./bindsnoop -E # report bind errors |
| ./bindsnoop --count # count bind per src ip |
| ./bindsnoop --cgroupmap mappath # only trace cgroups in this BPF map |
| ./bindsnoop --mntnsmap mappath # only trace mount namespaces in the map |
| |
| it is reporting socket options set before the bins call |
| impacting system call behavior: |
| SOL_IP IP_FREEBIND F.... |
| SOL_IP IP_TRANSPARENT .T... |
| SOL_IP IP_BIND_ADDRESS_NO_PORT ..N.. |
| SOL_SOCKET SO_REUSEADDR ...R. |
| SOL_SOCKET SO_REUSEPORT ....r |
| |
| SO_BINDTODEVICE interface is reported as "IF" index |
