BinktermPHP Terminal Server

The BinktermPHP Terminal Server is the shared text-mode BBS experience used by both the Telnet and SSH daemons. Once users are logged in, they interact with the same menus, handlers, and API-backed features regardless of transport.

Access methods: - Telnet daemon: TelnetServer.md - SSH daemon: SSHServer.md

Requirements

• PHP 8+
• PHP extensions: - `curl` ? for API requests - `pcntl` ? for process forking on Linux/macOS (multiple concurrent connections; single-connection on Windows)
• `libsixel-bin` (optional) ? provides `img2sixel` for inline image rendering in Sixel-capable terminal clients (`apt install libsixel-bin`)
• BinktermPHP web API reachable (defaults to `SITE_URL` from config)

Each transport daemon has additional extension requirements ? see TelnetServer.md and SSHServer.md.

Shell Availability

The .env variable TERMSERVER_ALLOWEDSHELLS controls which terminal shell modes users and sysops may select. It accepts a space-separated list of shell IDs registered with the terminal shell registry. Built-in shell IDs are:

• `tui`
• `line`

Examples:

• `TERMSERVER_ALLOWEDSHELLS=tui` ? only the full-screen TUI shell is selectable
• `TERMSERVER_ALLOWEDSHELLS=tui line` ? both shells are selectable
• `TERMSERVER_ALLOWEDSHELLS=tui retroglass` ? built-in TUI plus a custom shell plugin

If the variable is unset or empty, BinktermPHP defaults to tui only. The terminal settings screen and Admin -> BBS Settings -> Terminal Server Settings only show the shells permitted by this allowlist. If an older saved preference or other request tries to use a shell that is no longer allowed, the session falls back to the TUI shell.

Custom shells can be added by placing plugin definition files in telnet/shells/. See telnet/shells/README.md and TerminalServerDevGuide.md for the plugin format.

Core Functionality

• Netmail browsing, reading, composing, replying, and sending
• Echomail browsing, threaded reading, composing, replying, and posting
• QWK offline mail packet download and upload (when enabled)
• File areas browsing with ZMODEM downloads and uploads
• Bulletins (read-only system announcements posted by admins)
• Polls (view/vote/create where enabled)
• Terminal shell abstraction for feature-level UI intents, with a widget-backed TUI path and a prompt-driven line shell path for low-capability sessions
• Shoutbox (view/post where enabled)
• Local chat with rooms, direct messages, online users, and moderation shortcuts
• BBS Directory (browse other BBSes when enabled)
• Nodelist browser (browse Fidonet nodelist entries when available)
• Interests (tag-based content interests when enabled)
• Door launcher integration (DOS doors, native doors, and configured door menu)
• Who's Online display
• Reusable public profile viewer for terminal user lookups
• Full-screen message editor with cursor navigation and line editing controls
• ANSI color and screen-aware rendering (auto-detected on Telnet via TTYPE negotiation)
• Sixel image rendering for terminal clients that support it
• Per-user localization (same i18n flow used by web/API)
• User preferences and settings (editor behavior, display options, and other per-user configuration)

Features

The terminal server uses a shell abstraction layer (TuiShell for normal-size terminals, LineShell for low-capability sessions) to present UI intents consistently across feature handlers. For architecture details, the widget reference, shell selection rules, style profile, and developer patterns see Terminal Server Developer Guide.

Screen-Aware Display

• Automatically detects terminal dimensions via NAWS (Negotiate About Window Size)
• Adapts message lists to fit available screen height
• Prevents list overflow on different terminal sizes
• Dynamic pagination based on terminal rows
• Terminal resize events are processed in real time during key-wait loops ? the main menu re-renders immediately when the window is resized, without requiring a keypress
• On narrow terminals, the fallback main-menu header truncates cleanly and prefers keeping the BBS name visible before dropping the clock
• On short terminals, all selector screens (netmail inbox, echomail list, file areas, etc.) clip content from the bottom ? the title row and header are always rendered first and never scrolled off. The status bar is always anchored to the last terminal row.
• On narrow terminals, list rows are ANSI-aware truncated at the right edge so colors (bold unread, cyan row numbers, etc.) are preserved. The status bar is likewise hard-capped to one line so it cannot wrap and cause the screen to scroll.
• The main menu clips lower menu sections from the bottom on short terminals so the box header (status line, box border, "Main Menu" title) always remains visible.

Message Browsing

• List netmail and echomail messages with pagination
• Navigate between pages
• View message details with headers
• Thread awareness and proper message display
• ANSI color support for enhanced readability
• Unread messages are displayed in bold in both the echomail and netmail message lists. Once a message is opened and marked read, it renders at normal weight the next time the list is shown.
• Netmail reader supports Inbox and Sent folder views ? press `S` from the message list to toggle. The active folder is persisted per user across sessions. In Sent view, the message header shows the recipient (`To:`) instead of the sender, and replying pre-fills the original recipient's address.
• Press `B` in the netmail viewer to bookmark (save) a message for later. Pressing `B` again unsaves it. The status bar label toggles between Bookmark and Unsave to reflect the current state.
• Press `E` in the netmail viewer to forward the current message to the logged-in user's email address. Requires outbound email to be configured on the BBS; an error is shown inline if it is not.
• Press `B` in the echomail viewer to bookmark (save) a message for later. Pressing `B` again unsaves it. Bookmarked messages appear under the Saved filter in the web interface.
• Press `T` in the echomail viewer to download the current message as a plain-text `.txt` file via ZMODEM. The filename is derived from the message subject. Uses the built-in ZMODEM implementation by default; no additional software required.
• Press `E` in the echomail viewer to forward the current message to the logged-in user's email address. Requires outbound email to be configured on the BBS; an error is shown inline if it is not.
• Press `F` in the echomail viewer to forward the current message. A dialog prompts the user to choose Echomail (forward to another subscribed echoarea ? opens compose pre-filled with a `Fwd:` subject, attribution header, and quoted body) or Netmail (forward as a netmail to an FTN address ? uses the standard netmail compose flow). The source echoarea appears in the attribution header in both cases.
• Press `G` in the echomail viewer to add an ignore rule for the current message's sender. A sub-menu offers three options: By sender name (hides all future messages from that name), By FTN address (hides messages from that name at that address ? only shown if the message carries an FTN address), and Subject keyword (hides future messages from that sender whose subject contains the given keyword). Options 1 and 2 show a confirmation dialog pre-filled from the message header; option 3 prompts for a keyword string. The rule is saved via `POST /api/messages/echomail/ignore-rules`. `G` is available in the Ctrl-K help overlay only (not the status bar).
• Press `G` from the echoarea list to open the Ignore Rules management screen. Rules are fetched from `GET /api/user/echomail-ignore-rules` and displayed in a paginated selectable list. Each row shows the sender name and, where set, the FTN address and subject keyword. Select a rule and press Enter or `D` to delete it after confirmation via `DELETE /api/user/echomail-ignore-rules/{id}`. `G` appears in the Ctrl-K help overlay on the echoarea list.
• The echoarea list (the screen showing your subscribed areas) uses the same navigable list interface as message lists. Arrow Up/Down moves the highlight cursor; Arrow Left/Right (or `n`/`p`) changes pages; Enter selects the highlighted area; typing a number jumps the cursor to that row. A status bar at the bottom shows available actions. Press `/` to filter the list by tag or description, `C` to clear the filter, and (when Interests is enabled) `I` to open the interests browser. The list redraws immediately on terminal resize.
• The file areas list and the per-area file browser now use the same navigable selector interface as echomail. Arrow Up/Down moves the highlight cursor, Arrow Left/Right changes pages, Enter opens the highlighted area or file, and typing a number jumps to that row before Enter confirms it. The file browser keeps folders first, files second, and exposes download/upload/up-folder actions through the status bar.
• Opening a file from the terminal file browser now shows a centered file info modal instead of a full-screen text page. The modal matches the terminal dialog style, supports live resize, and allows scrolling long descriptions with Up/Down or PgUp/PgDn before closing with `B`, `Q`, or Enter. When downloads are enabled, pressing `D` from the modal downloads the current file directly.
• Selecting an empty echomail area (one with no messages yet) now opens the message list interface as normal. The area title and status bar are displayed, and the user can press `C` to compose a new message or `Q` to return to the echoarea list. Previously, entering an empty area immediately printed "No echomail messages." and returned the user to the list without allowing interaction.
• Press `A` from the echoarea list to toggle between "My Areas" (subscribed only) and "All Areas" (every area on the BBS). In All Areas mode each row shows a `[+]` badge when you are subscribed or `[ ]` when you are not. Selecting an unsubscribed area shows a dialog offering Subscribe & Browse, Browse Only, or Cancel. Press `U` on any subscribed area to unsubscribe via a confirmation dialog. If your subscribed list is empty, pressing `A` switches directly to All Areas so you can discover and subscribe to areas without leaving the terminal.
• The interests browser (opened with `I` from the echoarea list) uses the same navigable list interface: arrow keys or number+Enter to select an interest, Q to return to the echoarea list.
• Press `S` from the echoarea list to search all subscribed echomail areas. Enter a search term (minimum 2 characters); results from all areas are shown in a flat list with the area tag prepended to the From column. Press `S` from within a specific area's message list to search that area only. When opening a message from search results, matching text is highlighted in the message body (white text on yellow background).
• The generic terminal selector now supports multi-select state for callers that need bulk actions. In the echomail message list, press `Space` to toggle the highlighted message in or out of the selection set; selected rows show a `*` marker.
• Press `Ctrl-K` in any terminal selector list to open the key-binding help overlay. The overlay now includes the list-specific secondary actions that were removed from the status bar.
• Press `M` from an echomail area's message list to mark the selected messages as read. The terminal prompts for confirmation, submits the selected message IDs to the same bulk-read API used by the web interface, then redraws the list so unread indicators clear immediately.
• The terminal nodelist browser shows roll-up counts while browsing. The top-level network list displays both the number of nets and the total number of nodes in each zone/domain, and the per-net list shows the node count for each net before you open it.
• Press `Space` in the netmail inbox list to toggle the highlighted message in or out of the selection set (green `marker); pressM` tomark the selected messages as read*. Multi-select and M are available in the inbox only ? not the Sent folder. Ctrl-K shows both keys in the help overlay.
• Press `O` from the netmail message list to change the list sort order. The terminal netmail reader now exposes the same four sort modes as the web message list: Newest first, Oldest first, By subject, and By author. The selected sort is saved per user and restored the next time that user opens netmail from the terminal.
• Press `O` from an echomail area's message list to change the list sort order. The terminal reader exposes the same four sort modes as the web message list: Newest first, Oldest first, By subject, and By author. The selected sort is saved per user and restored the next time that user re-enters an echomail area from the terminal.
• In the terminal netmail address picker (opened with `?` at To Name or To Address), address-book autocomplete now also includes matching local BBS users by real name or username. Typing `sysop` returns the configured local system sysop as a local-delivery target, matching the web compose behavior.
• When entering netmail or echomail compose from the terminal, the server now checks for saved drafts of that message type. If any exist, the user is prompted to Resume Draft, New Message, or Cancel. Choosing resume opens a selector-style drafts picker with the same keyboard navigation as other terminal lists; pressing `X` deletes the highlighted draft after confirmation.
• When composing a new echomail message (not a reply), the compose flow asks "Cross-post to other areas? [y/N]:" immediately after showing the destination area. Answering `y` opens a checkbox picker listing all other subscribed areas. Use Up/Down arrows to navigate, Space to toggle each area, Enter to confirm, or Q to skip cross-posting. The number of additional areas is capped by the Max cross-post areas setting in the BBS admin (default 5). Scroll indicators (?/?) appear when the list is taller than the visible dialog area. If the terminal is resized while this picker is open, the compose-flow background is cleared and the picker is redrawn at the new size so old dialog content does not remain on screen.
• Terminal confirmation and selection dialogs now redraw on live resize. If the user resizes the window while a centered terminal dialog is open, both the background screen and the dialog reflow to the new dimensions instead of waiting for the dialog to close.
• The Who's Online main-menu action now opens a centered selectable popup instead of a plain text page. Highlight a user and press Enter to open a reusable terminal public profile viewer that shows username, full name, location, and biography. The profile view is read-only and uses the same resize-aware framed viewer style as other terminal reading screens.

Full-Screen Message Editor

• Arrow key navigation (Up, Down, Left, Right, Home, End, Page Up, Page Down)
• Insert and edit text at any cursor position
• Delete characters with Backspace/Delete
• The editor now uses the same framed blue panel style as the other terminal overlays, with a titled top border, bordered compose area, and a footer hint row. The `Ctrl-K` help screen uses the same dialog treatment instead of dropping to an unframed text page.
• Line operations: - Enter: Insert new line at cursor - Ctrl+Y: Delete entire current line
• Save/Cancel operations: - Ctrl+S: Save draft and keep editing (compose only) - Ctrl+Z: Save message and send - Ctrl+C: Cancel and discard message
• Visual feedback with colorized prompts
• Message quoting when replying
• If a compose flow was resumed from a saved draft, sending the message deletes that draft automatically.

Security

• Login Attempts: Limited to 3 attempts per connection before the connection is closed
• Connection Rate Limiting: The transport daemon (Telnet/SSH) enforces a per-IP connection rate limit before forking a child process ? see TelnetServer.md and SSHServer.md for transport-specific details
• Connection Logging: All login/logout events logged
• Telnet debug login shortcut: `telnet/telnet_daemon.php` accepts `--debug-user=NAME` for trusted local debugging. When set, the daemon creates a real authenticated session for that user and skips the normal login prompts. Use this only in development; it is not intended for production access.

Reliability

• API Retry Logic: Exponential backoff for failed API requests (up to 3 retries)
• Process Cleanup: Proper signal handling for SIGCHLD, SIGTERM, and SIGINT
• Connection Health: Timeout on socket accept operations
• Zombie Prevention: Automatic reaping of child processes

Sixel Image Rendering

When viewing messages in the terminal server, the inline Sixel image viewer can open:

• Markdown image references written as `` in markdown-formatted messages
• Bare direct image URLs in any message body when the URL ends in a supported raster extension: `.png`, `.jpg`, `.jpeg`, or `.gif`

The message body shows numbered image placeholders, and pressing I opens the viewer for the selected image. SVG and other non-raster extensions are not included in this terminal-side URL scan.

Sixel output requires img2sixel from the libsixel-bin package to be installed and available in PATH. If the binary is not found, images are silently omitted.

Main Menu Shell Behavior

The main menu adapts to the active shell:

• TuiShell (normal-size terminals): renders a framed two-column box with section headers (Messaging, Community/Explore, Files/Settings) and a customizable color status line. Navigation is single-key ? press the configured hotkey to enter a feature. When a `mainmenu.ans` or `mainmenu.sixel` art file is present, it is shown instead of the framed box. Terminal resize re-renders the menu immediately.
• LineShell (low-capability terminals): renders a plain prompt-driven shell and keeps the rest of the session in line mode as well. Main-menu hotkeys, message lists, selector screens, checkbox pickers, confirmation prompts, paged readers, working overlays, and profile/detail views all run through line-mode render/input loops instead of falling back to framed TUI widgets. These line-mode widgets rebuild their paging and wrapping layout on terminal resize, ignore stray queued CR/LF between screens, and use prompt-based commands rather than bottom-row cursor navigation. When a `mainmenu.ans` or `mainmenu.sixel` art file is present it is shown before the menu prompt; dashboard widgets are still omitted in this mode.

The shell is selected fresh on each menu loop iteration, so a resize that moves the terminal above the TuiShell threshold (60 cols × 16 rows) will switch from the numbered list to the framed box without a reconnect.

Main Menu Dashboard

The main menu displays a live dashboard panel alongside the navigation options (TuiShell only). The panel shows the same stats as the web dashboard, sourced from /api/dashboard/stats.

Widgets shown (in priority order):

| Widget | Content | |--------|---------| | Netmail | Unread netmail count | | Echomail | New echomail since last visit | | Online | Users active in the last 15 minutes | | Bulletins | Unread bulletins | | Credits | Credit balance (only when credits are enabled) |

Layout adapts to terminal width:

• Wide screens (? ~110 columns): A bordered panel is drawn to the right of the menu box using ANSI cursor positioning. Lower-priority widgets are dropped from the bottom when there is insufficient vertical space.
• Narrower screens: A compact single-line stats bar appears below the menu box. Bulletins and credits are omitted if there are no spare rows.

Stats are refreshed from the API after returning from netmail, echomail, or bulletins. On resize, the menu re-renders with the cached stats (no extra API call).

User Experience

• Colorized prompts and status messages
• Welcome message with BBS website URL
• Goodbye message on logout with reminder to visit website
• Unread and new message counts shown on main menu items (netmail: unread count; echomail: new since last visit)
• Live dashboard widgets alongside the main menu (see above)
• Shoutbox screens use the same centered framed panel style as other terminal viewers, with separate timestamp/author headers and wrapped message bodies for cleaner readability. The shoutbox viewer supports inline scrolling with Up/Down, PgUp/PgDn, Home, and End so you can page through more than one screen of messages, and shows a vertical scrollbar inside the frame.
• Helpful command documentation

Border and Frame Style

All terminal frames, box viewers, and paged content screens share a single configurable box-drawing style. The setting is stored in data/appearance.json under shell.term_border_style and is configured through Admin ? BBS Settings ? Appearance ? Terminal Server ? Border Style.

| Style | Description | Charset required | |-------|-------------|-----------------| | Classic (default) | Double-line corners and tees, single-line sides and dividers | CP437 or UTF-8 | | Double | All double-line box drawing | CP437 or UTF-8 | | Single | Thin single-line box drawing | CP437 or UTF-8 | | Heavy | Bold thick single-line box drawing | UTF-8 only | | Rounded | Thin single-line with curved corners | UTF-8 only | | Minimal | Top and bottom horizontal rules only; no side walls | CP437 or UTF-8 | | Mixed | Double horizontal lines, single vertical lines | CP437 or UTF-8 | | Shadow | Classic borders with a half-block drop shadow (?) on the right and bottom | UTF-8 only | | ASCII | Plus, hyphen, and pipe characters ? safe for any terminal | Any |

Examples:

Classic                         Double
????????????????????            ????????????????????
?      Title       ?            ?      Title       ?
????????????????????            ????????????????????
? Content line     ?            ? Content line     ?
????????????????????            ????????????????????

Single                          Heavy (UTF-8)
????????????????????            ????????????????????
?      Title       ?            ?      Title       ?
????????????????????            ????????????????????
? Content line     ?            ? Content line     ?
????????????????????            ????????????????????

Rounded (UTF-8)                 Minimal
????????????????????            ??????????????????
?      Title       ?                  Title
????????????????????            ??????????????????
? Content line     ?              Content line
????????????????????            ??????????????????

Mixed                           Shadow (UTF-8)
????????????????????            ?????????????????????
?      Title       ?            ?      Title       ??
????????????????????            ?????????????????????
? Content line     ?            ? Content line     ??
????????????????????            ?????????????????????
                                 ????????????????????

ASCII
+------------------+
|      Title       |
+------------------+
| Content line     |
+------------------+

Charset fallback: The rendered style is determined by both the configured setting and the connecting client's detected character set:

• UTF-8 terminal ? all styles render as configured.
• CP437 terminal ? Heavy falls back to Classic; Rounded falls back to Single. All other styles are unchanged.
• ASCII terminal ? always renders as ASCII regardless of the configured style.
• ANSI color disabled on a UTF-8 or CP437 terminal ? borders still use the normal character-set-appropriate line-drawing glyphs; only color is removed.

Customizable Main Menu Keys

Every action in the terminal main menu can be bound to a different single letter or digit (0?9) by the sysop. The binding is stored in data/appearance.json under shell.term_menu_keys and is configured through Admin ? BBS Settings ? Appearance ? Terminal Server ? Main Menu Keys. The key table in that UI shows the built-in default for each action in a center reference column.

Default key map:

| Key | Action | |-----|--------| | N | Netmail | | E | Echomail | | S | Shoutbox | | U | Bulletins | | P | Polls | | D | Door Games | | F | Files | | T | Settings | | I | Interests | | W | Who's Online | | K | QWK Offline Mail | | B | BBS Directory | | L | Node List | | C | Local Chat | | Q | Quit |

If no custom map is saved the built-in defaults above are used. When a custom map is saved, any action with no assigned key is hidden from the menu and its slot is not rendered ? remaining items in that section reflow to fill the gap. When every action in a section (Messaging, Community/Explore, or Files/Settings) is unassigned, the section header itself is suppressed. The quit key is always required. Sysops are responsible for ensuring their mainmenu.ans art matches whatever keys are configured.

The key map is returned as part of the GET /api/config/session-init call made immediately after login.

Local Chat

The terminal server includes the same local chat system used by the web UI. From the main menu, press the configured Local Chat key (default C) to open local chat.

Local chat supports:

• room selection from an in-chat navigation pane
• direct messages to online users and known DM contacts
• unread badges for rooms and DMs during the current chat session
• unread room and DM entries highlighted in green when they are not currently open
• online user display in the left navigation pane
• message polling with automatic updates while the chat screen is open
• scrollback with PgUp/PgDn
• Markdown rendering in the message pane using the shared terminal markup renderer
• automatic reopen to the last selected room or DM
• multiline compose via Ctrl+E

Chat controls:

• Tab / Shift+Tab ? move focus between panes
• Up / Down / Home / End ? move within the focused pane
• Enter ? open selected room/DM or send the current message
• PgUp / PgDn ? scroll message history
• Ctrl+E ? open the full-screen multiline composer
• Ctrl+K ? show local chat help
• R ? refresh rooms and online users
• Ctrl+C ? exit local chat

The current wide layout uses:

• a narrower Rooms / DMs pane on the left
• a larger Messages pane on the right
• a full-width Compose box at the bottom

The left pane also includes the current online-user summary, so there is no separate right-hand online-users sidebar.

Chat messages are rendered as terminal Markdown, matching the message-body renderer used by echomail and netmail viewers. Sender and timestamp are shown as a header line above each rendered message body.

Incoming local chat messages do not emit terminal bell characters. New unread rooms and DMs are indicated visually in the navigation pane instead.

On narrower terminals the chat client switches to a stacked layout so rooms/DMs, messages, and the compose box still fit on screen.

Idle Timeout

After a configurable period of inactivity the session displays an "Are you still there?" prompt. If no key is pressed before a second configurable deadline the session is disconnected. Any keypress resets the timer. The thresholds are set in Admin ? BBS Settings ? Terminal Idle Timeout and default to 5 minutes for the warning and 7 minutes for the disconnect.

Login Menu

Before authenticating, users are shown a pre-login menu:

• L ? Login to existing account
• R ? Reset lost password
• N ? Register a new account
• K ? QWK transfer (only shown when QWK is enabled)
• Q ? Quit / disconnect

New users who register are disconnected after registration and must reconnect to log in.

Terminal Detection Wizard

On first login, if the user has no saved terminal settings, the server runs an auto-detection wizard that tests character set support and color capability, then saves the results. This wizard is skipped on subsequent sessions once settings are stored.

The normal terminal settings screen is part of the shared tabbed settings UI, but the detection wizard itself intentionally remains a simple prompt-driven flow across all shells. This keeps first-run terminal detection working even when full shell rendering cannot yet be assumed to work correctly.

System News

After login, the server displays any pending system news before presenting the main menu.

Shared Session Model

Both transport daemons run the same BbsSession flow: transport handshake ? pre-login menu ? authentication ? main menu and feature handlers ? logout. Because the feature handlers are shared, behavior and capabilities remain consistent across Telnet and SSH. For the full session lifecycle and $state key reference see Terminal Server Developer Guide.

Transport-Specific Notes

• Telnet: - Uses telnet option negotiation (IAC/NAWS/echo control) and optional TLS listener - Supports an optional ANSI login screen (`telnet/screens/login.ans`)
• SSH: - Uses encrypted SSH-2 transport and host-key authentication model - Supports direct login when SSH credentials validate successfully - Passes PTY dimensions from `pty-req` to the BBS session - Sixel capability probing for SSH runs inside the SSH transport layer before `BbsSession` starts, so the DA reply can be consumed there without leaking into pre-login prompts

Custom Terminal Screens

Terminal login, main-menu, and goodbye screens are loaded from telnet/screens/. Both ANSI (.ans) and Sixel (.sixel) assets support simple rotating families:

• `login.ans`, `login1.ans`, `login2.ans`
• `login.sixel` (Sixel login screen; shown instead of ANSI when the client supports Sixel)
• `mainmenu.ans`, `mainmenu1.ans`
• `mainmenu.sixel`, `mainmenu1.sixel`
• `bye.ans`, `bye1.ans`
• `bye.sixel` (Sixel goodbye screen; shown instead of ANSI when the client supports Sixel)

When multiple files share the same base name and extension, the terminal server uses a simple glob match and picks one at random each time that screen is shown.

Editor Controls

Cursor Navigation

• Arrow Keys (Up/Down/Left/Right) ? Move cursor position
• Home ? Jump to beginning of current line
• End ? Jump to end of current line
• Page Up ? Scroll up one screen
• Page Down ? Scroll down one screen

Editing

• Backspace/Delete ? Delete character at or before cursor
• Enter ? Insert new line at cursor position
• Ctrl+Y ? Delete entire current line

Save/Cancel

• Ctrl+Z ? Save message and send
• Ctrl+C ? Cancel and discard message

Visual Feedback

The editor displays help text at the top of the screen showing available commands with color-coded indicators:

• Green: Save command
• Red: Cancel command
• Yellow: Delete line command

Platform Limitations

• Windows: Single connection only (no `pcntl_fork` support)
• Linux/macOS: Multiple concurrent connections supported via process forking

ZMODEM File Transfers

BinktermPHP includes a built-in PHP ZMODEM implementation that is used by default. It is preferred over external sz/rz binaries because it correctly handles Telnet IAC (0xFF) byte escaping, which external tools are not aware of. No additional software is required.

• Default behavior: terminal file transfers are disabled by default.
• To enable terminal file transfers, set the following in `.env`:

TERMINAL_FILE_TRANSFERS=true

The built-in implementation handles both downloads (sz) and uploads (rz).

Optional: external sz/rz binaries

External sz/rz binaries from the lrzsz package are supported but must be explicitly opted into by the sysop. To allow the external binaries to be used, set:

TELNET_ZMODEM_FORCE_PHP=false

When this is set, the server checks for sz/rz in PATH and uses them if found; if the binaries are not present the built-in PHP implementation is used as a fallback. You can specify explicit paths instead of relying on PATH:

TELNET_SZ_BIN=/usr/bin/sz
TELNET_RZ_BIN=/usr/bin/rz

> Note: External sz/rz binaries do not handle Telnet IAC escaping. They > work correctly over SSH but may produce corrupt transfers over plain Telnet > connections that pass binary 0xFF bytes in the data stream.

Related Documentation

• Telnet Daemon
• SSH Server