Configure PPP dial-in mode for a serial port

PPP dial-in allows the device to answer Point-to-Point Protocol (PPP) connections over serial ports.

To change the configuration to match the serial configuration of the device to which you want to connect:

Choose the management interface you want to use to access your device. Click a dropdown for instructions.
Digi Remote Manager
1. Log in to Digi Remote Manager.
1. Navigate to the device's dashboard.
Web UI

Log in to your device's Web UI.

Admin CLI

Log in to your device's Admin CLI via an SSH client, Telnet client, or terminal emulator.
Configure the settings.
Menu instructions
1. Click to open the device's configuration menu.
  - In Digi Remote Manager, on the device dashboard, click Settings.
  - In the Web UI, click Serial Configuration or Device Configuration > Serial.
2. Click to expand the name of the port that you want to configure, for example, Port 1.
  The serial port is enabled by default. To disable, toggle off Enable.
3. For Mode, select PPP-Dial-in. The default is Remote Access.
4. (Optional) For Label, enter a label that will be used when referring to this port.
5. For Baud rate, select the baud rate used by the device to which you want to connect. The default is 9600.
  - Max baud rate: 230400
  - Minimum: 50
    
    For a complete list, see Baud rate options.
6. For Flow control, select the type of flow control used by the device to which you want to connect. The default is None.
7. Enable Altpin to use the Altpin feature. Altpin is disabled by default. If you enable Altpin in EIA-232 mode, the DCD and DSR signals are swapped. This allows use of DCD with 8-wire cables. Altpin has no impact on 422 or 485 mode. For more information, see Serial connector pinout.
8. For Idle timeout, type the amount of time that the active session can be idle before the session is disconnected.
  
  Allowed values are any number of weeks, days, hours, minutes, or seconds, and take the format number{w|d|h|m|s}.
  
  For example, to set Idle timeout to ten minutes, enter 10m or 600s.
9. For Signaling, select the electrical signaling interface type used on this serial port:
  - RS-232. This is the default.
    Enable RTS Toggle if you want to enable RTS toggling during transmission on this serial port. If enabled, this setting overrides RTS\CTS flow control.
    For RTS Pre-delay, enter the amount of time RTS is asserted before starting data transmission. The time is measured in milliseconds. The default is 0ms.
    For RTS Post-delay, enter the amount of time RTS is deasserted before completing data transmission. The time is measured in milliseconds. The default is 0ms.
  - RS-422
    
    Enable Termination if you want to enable electrical termination on this serial port.
  - RS-485
    
    Enable Termination if you want to enable electrical termination on this serial port.
    
    Enable Full Duplex if you want to enable full duplex communication on this serial port.
    
    Enable Four Wire (or Four-Wire Communication) if you want to enable four-wire communication on this serial port. This option is disabled by default.
10. Click to expand PPP dial-in.
11. For Local IP address, type the IP address assigned to this interface.
12. For Remote IP address, type the IP address assigned to the remote peer.
13. For Metric, set the priority of routes associated with this interface. If there are multiple active routes that match a destination, then the route with the lowest metric will be used.
14. For Default route, toggle to control whether a default route gets added for the PPP interface. This feature is disabled by default.
15. For Zone, select the firewall zone for this interface. This can be used by packet filtering rules and access control lists to restrict network traffic on this interface.
16. For Authentication method, select the method used to authenticate the remote peer. Allowed values are:
  - None: No authentication is required.
  - Automatic: Attempt to authenticate using CHAP first, and then PAP.
  - CHAP: Use Challenge Handshake Authentication Protocol (CHAP) to authenticate.
  - PAP: Use Password Authentication Protocol (PAP) to authenticate.
  If Automatic, CHAP, or PAP are selected, type the Username and Password used to authenticate the remote peer.
17. (Optional) Configure the serial port to use a custom PPP configuration file:
  1. Click to expand Custom PPP configuration.
  2. Click Enable to enable the use of a custom PPP configuration file.
  3. Click Override to override the default PPP configuration and only use the custom configuration file.
    
    If Override is not enabled, the custom PPP configuration file is used in addition to the default configuration.
  4. For Configuration file, paste or type the configuration data in the format of a pppd options file. Because the options are passed directly to the pppd command line, they should all be entered on a single line. For example:
    debug lcp-echo-interval 10 lcp-echo-failure 2
18. (Optional) Configure a script that will be run to prepare the link before PPP negotiations are started:
  1. Click to expand Connect script.
  2. Click Enable to enable the use of a connection script.
  3. For Connect script filename, type the name of the script. Scripts are located in the /etc/config/serial directory. An example script, windows_dun.sh is provided.
    
    Example windows_dun.sh file:
    #!/bin/sh # Example connect script for connecting from a PC using a Windows dial-up # networking connection with built-in standard 33600 bps modem driver and phone # number 123. # The shell's 'read' builtin breaks on newline, so translate incoming carriage- # return to newline, and outgoing newline to carriage-return-newline. stty icrnl onlcr opost # Read input from the serial port, one line at a time. while read -r line; do case "$line" in ATDT123) echo "CONNECT" # instruct the peer to start PPP exit 0 # start up the local PPP session ;; AT*) echo "OK" # passively accept any other AT command ;; esac done
19. Click Apply to save the configuration and apply the change.
CLI instructions
1. At the CLI prompt, type config and then press Enter.
2. The serial port is enabled by default. To disable:
```
(config)> serial port1 enable false
(config)>
```
3. Set the mode:
```
(config)> serial port1 mode ppp_dialin
(config)>
```
4. (Optional) Set a label that will be used when referring to this port.
```
(config)> serial port1  label label
(config)>
```
5. Set the baud rate used by the device to which you want to connect:
```
(config)> serial port1 baudrate rate
(config)>
```
  where rate is the desired baud rate:
  - Default baud rate: 9600
  - Max baud rate: 230400
  - Minimum baud rate: 50
    For a complete list, see Baud rate options.
6. Set the type of flow control used by the device to which you want to connect:
```
(config)> serial port1 flow value
(config)>
```
  where value is one of:
  - none
  - rts/cts
  - xon/xoff
7. Set the amount of time that the active session can be idle before the session is disconnected:
```
(config)> serial port1 idle_timeout value
(config)>
```
  where value is any number of weeks, days, hours, minutes, or seconds, and takes the format number{w|d|h|m|s}.
  
  For example, to set idle_timeout to ten minutes, enter either 10m or 600s:
```
(config)> serial port1 idle_timeout 600s
(config)> 
```
8. Enable Altpin to use the Altpin feature. Altpin is disabled by default. If you enable Altpin in EIA-232 mode, the DCD and DSR signals are swapped. This allows use of DCD with 8-wire cables. Altpin has no impact on 422 or 485 mode. For more information, see Serial connector pinout.
```
(config)> serial port1 altpin true
(config)>
```
9. Set the local IP address assigned to this interface:
```
(config)> serial port1 ppp_dialin local_address IPv4_address
(config)>
```
10. Set the IP address assigned to the remote peer:
```
(config)> serial port1 ppp_dialin remote_address IPv4_address
(config)>
```
11. The default route is added for the PPP interface is disabled by default. To enable:
```
(config)> serial port1 ppp_dialin default_route true
config)>
```
12. Set the authentication method used to authenticate the remote peer:
```
(config)> serial port1 ppp_dialin auth value
(config)>
```
  where value is one of:
  - none: No authentication is required.
  - auto: Attempt to authenticate using CHAP first, and then PAP.
  - chap: Use Challenge Handshake Authentication Protocol (CHAP) to authenticate.
  - pap: Use Password Authentication Protocol (PAP) to authenticate.
  The default is none.
  
  If auto, chap, or pap are set, set the username and password used to authenticate the remote peer:
```
(config)> serial port1 ppp_dialin username username
(config)> serial port1 ppp_dialin password password
(config)>
```
13. Set the priority of routes associated with this interface. If there are multiple active routes that match a destination, then the route with the lowest metric will be used.
```
(config)> serial port1 ppp_dialin metric int
(config)>
```
  The default is 10.
14. Set the firewall zone for this interface. This can be used by packet filtering rules and access control lists to restrict network traffic on this interface.
  1. Use the ? to determine available zones:
    (config)> serial port1 ppp_dialin zone ? Zone: The firewall zone assigned to this interface. This can be used by packet filtering rules and access control lists to restrict network traffic on this interface. Format: any dynamic_routes edge external internal ipsec loopback setup Default value: internal Current value: internal (config)>
  2. Set the zone:
    (config)> serial port1 ppp_dialin zone zone (config)>
15. (Optional) Configure the serial port to use a custom PPP configuration file:
  1. Enable the use of a custom PPP configuration file:
    (config)> serial port1 ppp_dialin custom enable true (config)>
  2. Enable override to override the default PPP configuration and only use the custom configuration file:
    (config)> serial port1 ppp_dialin custom override true (config)>
    
    If override is not enabled, the custom PPP configuration file is used in addition to the default configuration.
  3. Paste or type the configuration data in the format of a pppd options file:
    (config)> serial port1 ppp_dialin custom config_file data (config)>
    
    where data are one or more pppd command line options. Because the options are passed directly to the pppd command line, they should all be entered on a single line. For example:
    (config)> serial port1 ppp_dialin custom config_file "debug lcp-echo-interval 10 lcp-echo-failure 2" (config)>
16. (Optional) Configure a script that will be run to prepare the link before PPP negotiations are started:
  1. Enable the use of a connection script.
    (config)> serial port1 ppp_dialin connect enable true (config)>
  2. Set the name of the script:
    (config)> serial port1 ppp_dialin connect script filename (config)>
    
    Scripts are located in the /etc/config/serial directory. An example script, windows_dun.sh is provided.
    
    Example windows_dun.sh file:
    
    #!/bin/sh # Example connect script for connecting from a PC using a Windows dial-up # networking connection with built-in standard 33600 bps modem driver and phone # number 123. # The shell's 'read' builtin breaks on newline, so translate incoming carriage- # return to newline, and outgoing newline to carriage-return-newline. stty icrnl onlcr opost # Read input from the serial port, one line at a time. while read -r line; do case "$line" in ATDT123) echo "CONNECT" # instruct the peer to start PPP exit 0 # start up the local PPP session ;; AT*) echo "OK" # passively accept any other AT command ;; esac done
17. Save the configuration and apply the change.
```
(config)> save
Configuration saved.
>
```
18. Type exit to exit the Admin CLI.
  Depending on your device configuration, you may be presented with an Access selection menu. Type quit to disconnect from the device.