sngrep(8) SIP Messages flow viewer


sngrep [-hVcivlkNq] [ -IO pcap_dump ] [ -d dev ] [ -l limit ] [ -k keyfile ] [ <match expression> ] [ <bpf filter> ]


sngrep is a terminal tool that groups SIP (Session Initiation Protocol) Messages by Call-Id, and displays them in arrow flows similar to the used in SIP RFCs. The aim of this tool is to make easier the process of learnig or debugging SIP. It recognizes UDP, TCP and partially TLS SIP packets and understands bpf filter logic in the same way ngrep (8) and tcpdump (1) does.


Display help and usage information.

Display version information.

Only capture dialogs starting with an INVITE request.

Make match expression case insensitive.

Invert match expression.

-I pcap_dump
Read packets from pcap file instead of network devices. This option can be used with bpf filters.

-O pcap_dump
Save all captured packets to a pcap file. This option can be used with bpf filters.

-d dev
Use this capture device instead of default (any).

-k keyfile
Use private keyfile to decrypt TLS packets.

-l limit
Change default capture limit (10000 dialogs)

Don't display sngrep interface, just capture

Don't print captured dialogs in no interface mode

match expression
Match given expression in Messages' payload. If one request message matches the given expression, the following messages within the same dialog will be also captured.

bpf filter
Selects a filter that specifies what packets will be parsed. If no bpf filter is given, all SIP packets seen on the selected interface or pcap file will be displayed. Otherwise, only packets for which bpf filter is `true' will be displayed.


There are multiple windows to provide different information. Most of the program windows have a help dialog with a brief description and useful keybindings.

Call List Window

The first window that sngrep shows is Call List window and display the different SIP Call-Ids found in messages. The displayed columns depends on your terminal width and your custom configuration. You can move between dialogs with arrow keys and selected them using Spacebar. Selecting multiple dialogs will display all them in Call flow window and Call Raw window, and will allow to save only the selected message dialogs to a PCAP file.

Call Flow Window

This window will a flow diagram of the selected dialogs' messages. The selected message payload will be displayed in the right side of the window. You can move between messages using arrow keys and select them using Spacebar. Selecting multiple messages will display the Message Diff Window.

Call Raw Window

This window will display the selected dialog messages in plain text. It was designed to allow copying the messages payload easily. You can also save the displayed information to a text file from this screen.

Column selection Window

Columns displayed in Call List can be updated in this window. You can add or remove columns or change their order in the list. Additionally, you can save column state to be use in next sngrep execution.

Message Diff Window

This window will compare two messages. Right now the comparison is done searching each line in the other message, highlighting those not found exactly. You can reach this window by selecting two messages using Spacebar in Call Flow window


Full paths below may vary between installations.


System-wide configuration file. Some sngrep options can be overridden using this file.


User's configuration file. If this file is present, options will be override system-wide configurations.


Please report bugs to the sngrep github project at

Non-bug, non-feature-request general feedback should be sent to the author directly by email.


Written by Ivan Alonso [a.k.a. Kaian] <[email protected]>.