---
name: "atmsigd"
section: "8"
platform: "linux"
package: "linux-atm"
version: "2.5.2-9"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/atmsigd"
---

# atmsigd(8)

ATM signaling demon

## NAME

atmsigd - ATM signaling demon

## SYNOPSIS

**atmsigd** \[**-b**\] \[**-c *config\_file***\] \[**-d**\] \[**-D *dump\_dir***\] \[**-l *logfile***\] \[**-m *mode***\] \[**-n**\] \[**-q *qos***\] \[**-t *trace\_length***\] \[**-u *uni\_version***\] \[**\[*itf*.\]*vpi*.*vci*** \[***input output***\]**\]**\
 **atmsigd** **-V**

## DESCRIPTION

**atmsigd** implements the ATM UNI signaling protocol. Requests to establish, accept, or close ATM SVCs are sent from the kernel (using a comparably simple protocol) to the signaling demon, which then performs the dialog with the network.

Note that **atmsigd** is not able to accept or establish connections until the local ATM address of the interface is configured by **ilmid** or manually using **atmaddr**.

The default signaling VC (interface 0, VPI 0, VCI 5) can be overridden on the command line by specifying a different PVC address.

When overriding the default VC, optionally a pair of named pipes to use for communicating with the user of signaling can be specified. Normally, the kernel is the user of signaling and **atmsigd** opens a special socket for communication with it.

If **atmsigd** is killed, all system calls requiring interaction with it will return with an error and set **errno** to **EUNATCH**.

## OPTIONS

- **-b**

  Run in background (i.e. in a forked child process) after initializing.

- **-c** *config\_file*

  Use the specified configuration file instead of **/etc/atmsigd.conf** If an option is specified in the configuration file and on the command line, the command line has priority.

- **-d**

  Enables (lots of) debugging output. By default, **atmsigd** is comparably quiet.

- **-D** *dump\_dir*

  Specifies the directory to which **atmsigd** will write status and trace dumps. If **-D** is not specified, dumps are written to /var/tmp.

- **-l** *logfile*

  Write diagnostic messages to the specified file. The special name **syslog** is used to send diagnostics to the system logger, **stderr** is used to send diagnostics to standard error. If **-l** is absent, the setting in **atmsigd.conf** is used. If **atmsigd** doesn't specify a destination either, messages are written to standard error.

- **-m** *mode*

  Set the mode of operation. The following modes are available: **user** for the user side (the default), **network** for the network side (useful if you have two PCs but no switch), and **switch** for operation with a signaling relay in a switch.

- **-n**

  Prints addresses in numeric format only, i.e. no address to name translation is attempted.

- **-q** *qos*

  Configures the signaling VC to use the specified quality of service (see [qos(7)](/qos/7.md) for the syntax). By default, UBR at link speed is used on the signaling VC.

- **-t** *trace\_length*

  Sets the number of entries that should be kept in the trace buffer. **-t 0** disables tracing. If **-t** is not specified, **atmsigd** uses a default of 20 trace entries.

- **-u** *uni\_version*

  Sets the signaling mode. The following modes are supported: **uni30** for UNI 3.0, **uni31** for UNI 3.1, **uni31+uni30** for UNI 3.1 with 3.0 compatibility, **uni40** for UNI 4.0, and **uni40+q.2963.1** for UNI 4.0 with Q.2963.1 peak cell rate renegotiation.

- **-V**

  Prints the version number of **atmsigd** on standard output and exits.

## FILES

- **/etc/atmsigd.conf**

  default configuration file

- **/var/tmp/atmsigd.*pid*.status.*version***

  default location of status dumps

- **/var/tmp/atmsigd.*pid*.trace.*version***

  default location of signaling trace dumps

## DEBUGGING

When receiving a **SIGUSR1** signal, **atmsigd** dumps the list of all internal socket descriptors. With **SIGUSR2**, it dumps the contents of the trace buffer. If a dump directory was set, dumps are written to files called **atmsigd.***pid***.status.***number* and **atmsigd.***pid***.trace.***number*, respectively, with *number* starting at zero and being incremented for every dump. If no dump directory is set, dumps are written to standard error.

Dumps are also generated whenever **atmsigd** detects a fatal error and terminates. No attempt is made to catch signals like **SIGSEGV**.

## BUGS

The generation of traces is a comparably slow process which may already take several seconds for only 100 trace entries. To generate a trace dump, **atmsigd** therefore forks a child process that runs in parallel to the signaling demon.

## AUTHOR

Werner Almesberger, EPFL ICA \<Werner.Almesberger@epfl.ch\>

## SEE ALSO

[atmaddr(8)](/atmaddr/8.md), [atmsigd.conf(4)](/atmsigd.conf/4.md), [ilmid(8)](/ilmid/8.md), [qos(7)](/qos/7.md)