| .TH tcpconnect 8 "2015-08-25" "USER COMMANDS" |
| .SH NAME |
| tcpconnect \- Trace TCP active connections (connect()). Uses Linux eBPF/bcc. |
| .SH SYNOPSIS |
| .B tcpconnect [\-h] [\-t] [\-x] [\-p PID] [-P PORT] |
| .SH DESCRIPTION |
| This tool traces active TCP connections (eg, via a connect() syscall; |
| accept() are passive connections). This can be useful for general |
| troubleshooting to see what connections are initiated by the local server. |
| |
| All connection attempts are traced, even if they ultimately fail. |
| |
| This works by tracing the kernel tcp_v4_connect() and tcp_v6_connect() functions |
| using dynamic tracing, and will need updating to match any changes to these |
| functions. |
| |
| Since this uses BPF, only the root user can use this tool. |
| .SH REQUIREMENTS |
| CONFIG_BPF and bcc. |
| .SH OPTIONS |
| .TP |
| \-h |
| Print usage message. |
| .TP |
| \-t |
| Include a timestamp column. |
| .TP |
| \-p PID |
| Trace this process ID only (filtered in-kernel). |
| .TP |
| \-P PORT |
| Comma-separated list of destination ports to trace (filtered in-kernel). |
| .SH EXAMPLES |
| .TP |
| Trace all active TCP connections: |
| # |
| .B tcpconnect |
| .TP |
| Trace all TCP connects, and include timestamps: |
| # |
| .B tcpconnect \-t |
| .TP |
| Trace PID 181 only: |
| # |
| .B tcpconnect \-p 181 |
| .TP |
| Trace ports 80 and 81 only: |
| # |
| .B tcpconnect \-P 80,81 |
| .SH FIELDS |
| .TP |
| TIME(s) |
| Time of the call, in seconds. |
| .TP |
| PID |
| Process ID |
| .TP |
| COMM |
| Process name |
| .TP |
| IP |
| IP address family (4 or 6) |
| .TP |
| SADDR |
| Source IP address. |
| .TP |
| DADDR |
| Destination IP address. |
| .TP |
| DPORT |
| Destination port |
| .SH OVERHEAD |
| This traces the kernel tcp_v[46]_connect functions and prints output for each |
| event. As the rate of this is generally expected to be low (< 1000/s), the |
| overhead is also expected to be negligible. If you have an application that |
| is calling a high rate of connects()s, such as a proxy server, then test and |
| understand this overhead before use. |
| .SH SOURCE |
| This is from bcc. |
| .IP |
| https://github.com/iovisor/bcc |
| .PP |
| Also look in the bcc distribution for a companion _examples.txt file containing |
| example usage, output, and commentary for this tool. |
| .SH OS |
| Linux |
| .SH STABILITY |
| Unstable - in development. |
| .SH AUTHOR |
| Brendan Gregg |
| .SH SEE ALSO |
| tcpaccept(8), funccount(8), tcpdump(8) |
