[Petyok]

Closes #174.

What changed

• feat: share this machine's network with a host from its session.
  • Key: Alt+Shift+N in an ssh session (rebindable) starts a second ssh connection to the same host, the "sidecar" (src/session/share_net.rs).
  • What the host gets: the sidecar carries only a reverse dynamic forward (-R 127.0.0.1:0), so the host gets a SOCKS5 proxy on its loopback whose traffic leaves from this machine.
  • Session untouched: the session itself is never reconnected, so a root shell stays.
  • Stopping: the same key stops it, and so do closing the tab, the session ending and quitting.
  • Footer: shows Alt+Shift+N share net, ⇄ net ..., ⇄ net :PORT · Alt+Shift+N stop or ⇄ net failed · Alt+Shift+N retry. It stays visible while scrolled back.
  • ssh log: the host's log gets one line with ready-to-paste apt and curl commands.
• Limits:
  • PermitRemoteOpen allows ports 80 and 443 only. The first entry is passed twice because OpenSSH 8.8 to 9.1 skip it (bz3515); checked on real 8.9 and 9.6 clients.
  • ControlMaster=no and ControlPath=none, because a mux master applies no limit.
  • StrictHostKeyChecking=yes, and ExitOnForwardFailure=no so the user's own ssh_config forwards cannot stop the share.
  • BatchMode when no secret is stored.
• Login: the stored password or key of the saved host, looked up again because the session drops its copy once authenticated. Jump-host secrets go through the tunnels' askpass staging.
• Lifecycle:
  • On Linux, PR_SET_PDEATHSIG ends the sidecar with sshub however sshub ends.
  • The sidecar is not in its own process group, so a terminal hangup reaches it.
  • Elsewhere only a SIGKILL of sshub can leave it running.
• Port: read from the sidecar's own -E log in a private 0700 dir; stderr, where a server banner lands, is never parsed.
• Refused cases: mosh, local shell and key-push tabs show a notice; the key does nothing until the session is connected.
• CLI: sshub connect <host> --share-net adds the same options inline.
• Docs: CHANGELOG (### Added), README feature and session key table, help, man page (--share-net), openwiki sessions-sftp.md and cli.md. All state the security trade-off: while sharing, any user on the host can reach what this machine reaches on ports 80/443.

How tested

• cargo fmt --check, cargo clippy --all-targets -D warnings, and just test (1740 + 127 + 127) are green.
• Oracle tests against the tempdir sshd with real ssh and curl, each confirmed to fail with its fix reverted:
  • the allowed ports pass and a non-allowed port is refused;
  • toggle off and session drop end the proxy and the ssh process;
  • a sidecar dies with a SIGKILLed parent;
  • AllowTcpForwarding no shows Failed and the session goes on;
  • a user ControlMaster is not used;
  • the user's own LocalForward does not stop the share;
  • a server banner cannot set the port or fail the share;
  • the startup command never runs in the sidecar;
  • a password host without a stored secret fails fast with the reason;
  • the stored password is looked up again after the session dropped its copy.
• Real binary in a PTY against a local sshd:
  • https://example.com returned 200 through the proxy, and a non-web port was refused.
  • The sidecar and the proxy port were gone after toggle off, Ctrl+W, closing the terminal, and kill -9 of sshub.
• The maintainer tried it on a real password host, which found the stored-password bug fixed in this PR.
• Adversarial review by 5 critics over two rounds. Verified findings fixed:
  • ControlMaster bypass;
  • footer hint evicting dashboard hints;
  • orphaned sidecar;
  • user forwards killing the sidecar;
  • banner forgery;
  • retry needing two presses;
  • starting before connect;
  • host-key reason wording;
  • scrolled footer.

Not changed

• A host whose password is not stored in SSHub, or that asks for a one-time code, cannot share: the background connection cannot show a prompt, so it fails with the reason. Routing its prompts through SSHub's login modal is follow-up work.
• On macOS a SIGKILL of sshub can leave the sidecar running. A sshub that dies abruptly leaves a small private log dir in /tmp.
• At 80 columns the Alt+Shift+N share net hint takes the place of Shift+drag in mouse apps.
• If the session reconnects after a host-key repair, it comes back unshared.

Written by Claude Opus 5.5 (Oh My Pi) on behalf of the maintainer.