To help debugging issues.
Also:
- bump sshd LogLevel to DEBUG1, for essential details.
- bump command output buffer in `run_command_varg()`
- drop redundant condition in `run_command_varg()`
- replace `BUFSIZ` with literal sizes in `run_command_varg()`.
After this patch it's showing this in the CI log for the libgcrypt
fallout that previously needed a long time to diagnose:
```
61: ---- sshd log ----
61: No matching private key for certificate: /etc/ssh/ssh_host_mldsa44-ed25519_key-cert.pub
61: Server listening on 0.0.0.0 port 22.
61: Server listening on :: port 22.
61: debug1: sshd-session version OpenSSH_10.5, OpenSSL 3.6.3 9 Jun 2026
61: Connection from 172.17.0.1 port 51878 on 172.17.0.2 port 22 rdomain ""
61: debug1: sshd-auth version OpenSSH_10.5, OpenSSL 3.6.3 9 Jun 2026 [preauth]
61: debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,rsa-sha2-512-cert-v01@openssh.com,
rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,
ecdsa-sha2-nistp256-cert-v01@openssh.com,ssh-ed25519,ssh-ed25519-cert-v01@openssh.com [preauth]
61: debug1: Local version string SSH-2.0-OpenSSH_10.5p1 Debian-1 [preauth]
61: debug1: Remote protocol version 2.0, remote software version libssh2_1.11.2_DEV [preauth]
61: debug1: compat_banner: no match: libssh2_1.11.2_DEV [preauth]
61: debug1: SSH2_MSG_KEXINIT sent [preauth]
61: debug1: SSH2_MSG_KEXINIT received [preauth]
61: debug1: kex: algorithm: (no match) [preauth]
61: Unable to negotiate with 172.17.0.1 port 51878: no matching key exchange method found.
Their offer: diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,
diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,
diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1,ext-info-c,
kex-strict-c-v00@openssh.com [preauth]
[...]
61: ------------------
```
Follow-up to 1d0b86ac84#2484
Follow-up to 8be5716437#2174
Follow-up to 51f6259d18#1720Closes#2621
In favor of direct execution or `docker login` and `docker logout`.
Also to limit the logged-in time to the steps the require it, and to
avoid passing a secret via the command-line.
Closes#2616
To overwrite default ones with the ones matching the copied private
keys.
Fixing in sshd log:
```
Public key for /etc/ssh/ssh_host_rsa_key does not match private key
Public key for /etc/ssh/ssh_host_ecdsa_key does not match private key
Public key for /etc/ssh/ssh_host_ed25519_key does not match private key
```
Closes#2614
To reflect the support for multiple container engines, and to make
terminology more consistent and implementation-agnostic.
Also:
- add FIXME for `docker-machine ip` command that has been dropped
upstream.
Follow-up to 9bd1f16dc2#2605Closes#2609
- add `FIXTURE_CONTAINER_CMD` to the container command. Supported:
`podman`, `container`, `docker` (default).
- deprecate `OPENSSH_NO_DOCKER` env. Replaced by setting
`FIXTURE_CONTAINER_CMD` to an empty string.
- GHA: replace Docker with `podman` in a some Linux jobs.
- openssh_fixture: fixup `inspect` commands to be compatible with both
docker and podman.
- openssh_fixture: add `inspect` fallback for podman, which does not
support `HostIp` before 6.1.0.
Ref: https://github.com/podman-container-tools/podman/issues/29164
- openssh_fixture: add Apple container alternatives for `pull` and
`tag`.
- openssh_fixture: fix `run` command to suppress progress output when
using Apple container.
- openssh_fixture: if `OPENSSH_SERVER_PORT` is set, omit querying
the port number via the container tool.
`podman` seems to be a tiny bit slower than Docker in CI.
Requirements for Apple container:
- Apple container 0.8.0+ (2026-01-02). Tested with 1.4.1.
- `jq` installed in PATH.
- setting the sshd port manually on the host via `OPENSSH_SERVER_PORT`
(`container` cannot automatically assign one).
- physical macOS machine.
Example to run conainerized tests on macOS:
```sh
brew install container jq
container system start --disable-kernel-install
container system kernel set --recommended
export FIXTURE_CONTAINER_CMD=container
export OPENSSH_SERVER_PORT=<free-port-number>
export OPENSSH_SERVER_IMAGE; OPENSSH_SERVER_IMAGE=ghcr.io/libssh2/ci_tests_openssh_server:$(git rev-parse --short=20 HEAD:tests/openssh_server)
ctest -VV
```
Also tried:
- using Apple container in CI. Does not work because nested
virtualization is not supported in GHA runners.
- installing WSL on Windows. Failed with cryptic error upon
`wsl --install --distribution Debian`.
Closes#2605
To enable testing on arm64 Linux and possibly also on macOS, and
possibly possibly on arm64 Windows.
Also:
- switch to debian:testing to trigger a container rebuild.
- Dockerfile: install `adduser` explicitly. Required for debian:forky.
- Dockerfile: stop installing suggested/recommended packages.
Ref: https://github.com/docker/build-push-actionCloses#2606
To use a key type that is:
- supported by all backends.
- can be generated with the most recent `ssh-keygen` version.
- here to stay for the foreseeable future.
(DSA is scheduled for removal from the libssh2 codebase.)
Cherry-picked from #2598Closes#2604
Should no longer be necessary after fixing the root cause.
(Though we do not run these tests in CI at the moment.)
Ref: #804
Follow-up to f216bbe3aa#2583
Follow-up to bc120a343b#1023Closes#2603
Fixing:
```
x86_64-w64-mingw32-ld: src/CMakeFiles/libssh2_shared.dir/Unity/unity_0_c.c.obj: in function `userauth_hostbased_fromfile':
src/userauth.c:923:(.text+0x34c29): undefined reference to `ssh2_pub_privkey'
x86_64-w64-mingw32-ld: src/CMakeFiles/libssh2_shared.dir/Unity/unity_0_c.c.obj: in function `userauth_publickey':
src/userauth.c:1745:(.text+0x37171): undefined reference to `ssh2_pub_privkey'
collect2: error: ld returned 1 exit status
```
Note: This fixes the build, but leaves `ssh2_pub_privkey()` a no-op, because it's not implemented for ECDSA.
Closes#2600
The WinCNG backend has been missing runtime tests for a while. To
restore some level of testing, this PR make use of curl's regression
test suite (`runtests`) to run SCP/SFTP-specific tests with the
master/PR libssh2 revision at hand. Some tests need to be disabled when
using the built-in Windows OpenSSH server.
The current CI jobs reproduce the long-running WinCNG flaky failure
reported in #804 reliability.
Note, if these CI jobs make libssh2 CI a pain to use, they will be
removed. This has a reasonably fair chance to happen, based on the
experience with curl CI with Windows.
Also:
- test both ECDH and non-ECDH builds.
- test build on x64 and ARM64.
- test with both Windows built-in OpenSSH port and MSYS2's sshd.
- enable debug logging in libssh2 while running the tests.
- for extra stress, run each of the 56-57 tests 6 times.
This may be lowered in a future commit to avoid flakiness and reduce
CI load and job times.
Caveats:
- as seen in curl CI, runtests may result in hangs due to broken pipes
and error 2304 for undiscovered reasons.
Discussion: https://github.com/curl/curl/discussions/14854
- MSBuild has an undisablable "smart" feature that sometimes marks a
successful run a failure.
Refs:
a477789c43https://github.com/curl/curl/pull/18301
- these tests are different in scope than libssh2's own.
- tests sometime fail flaky with:
```
Failure Event: -43 - Failed getting banner
```
Ref: https://github.com/libssh2/libssh2/actions/runs/34134974899/job/101783681252?pr=2590
- running on modern runner machines, the Win10-introduced DH algo is
always enabled.
Ref: https://github.com/libssh2/libssh2/discussions/2049
Ref: #2583Closes#2590
- normalize fixed-width WinCNG bignums before SSH `mpint` serialization
- apply the normalization to DH public values and DH/ECDH shared secrets
- zero the removed tail bytes and add common bignum conversion tests
WinCNG returns DH public values and raw DH/ECDH shared secrets in
fixed-width buffers. The WinCNG bignum retained that buffer width as its
numeric length. When a value started with `0x00`, libssh2 included the
redundant byte in the exchange hash even though RFC 4251 requires a
canonical `mpint` representation.
The peer hashes the normalized integer, so the exchange hashes differ
and a valid server host-key signature is rejected. This appeared
intermittently as `LIBSSH2_ERROR_KEY_EXCHANGE_FAILURE` because it
depends on the generated value.
The helper introduced here moves significant bytes to the start of the
existing allocation, explicitly clears the removed tail, and updates
only the logical length. It does not add an allocation or a new failure
path.
Reported-by: Dan Fandrich
Fixes#804
Ref: #2590 (tests)
Closes#2583
Omit direct backend-specific API use. Drop one test using negative
input, that's impossible with the internal crypto API. Using
backend-specific code in tests is highly undesired. It's also
discouraged to special-case any, in this case WinCNG had to be because
it does not implement the DH validation function.
Also:
- mbedtls: fix an internal API type difference with a cast.
- unfold a line.
Follow-up to fcf830788d#2239Closes#2595
To better hide backend-specific differences and t bring the init
sub-steps (1. allocation, 2. conversion) close to each other.
Also:
- HACKING_CRYPTO.md: fix docs for `ssh2_bn_from_bin()` and
`ssh2_bn_set_word()`.
Ref: https://github.com/libssh2/libssh2/pull/2583#discussion_r3948922721Closes#2594
Also:
- openssl: drop redundant local variable in non-OpenSSL3 branch.
- x11: drop redundant cast.
- silence false positives.
Follow-up to 0b915eab67#2586Closes#2588
If the server failed to serve the promised amount of data,
`sftp_packet_read()` could be stuck in a loop, prior to this patch.
Report-and-patch-by: RELAUNCH DEPT.
Fixes GHSA-2q3j-q544-xxp7
Closes#2581
tn the abitrary value of 32768. To avoid overflowing the counter and
letting it wrap around, and to avoid exhausting memory if the list is
large or keeps coming from the server.
Closes#2580
`libssh2_publickey_list_fetch()` preserves its packet-receive state when
a non-blocking channel returns `LIBSSH2_ERROR_EAGAIN`, but the
accumulated list, key count and capacity were local to a single
invocation.
Keep those aggregate values in the opaque publickey handle while a list
fetch is in progress. Restore them on retry, transfer ownership to the
caller on success, and release them on an error or subsystem shutdown.
Fixes GHSA-qwvp-xm4w-32m7
Closes#2578
The allocation reserves `max_keys + 1` entries, while the initialization
after growth currently covers only `max_keys - keys` entries. Include
the additional reserved entry in that initialization so the list
terminator is initialized at exact capacity boundaries.
Follow-up to c2f1a3a21b#2380
Ref: https://github.com/libssh2/libssh2/pull/2380#pullrequestreview-4746725158Closes#2579
To avoid the chance of breaking compatibility. Make an exception for
values also passed to `strlen()` because these were already not
supporting callers passing `x, y`-style macro expressions to these
macros, as arguments.
Also note that SFTP handle args already did not support this due to the
lack of parentheses in `libssh2_sftp_close()`, `libssh2_sftp_closedir()`
macros.
Follow-up to b6f307dca9#1898Closes#2577
In some cases this is binary, in others it's textual.
To better see what's in the keys, to debug them, and debug code dealing
with them. It's a manual script, not run automatically by this repo.
Closes#2574
It could happen with base paths too large to fit into the 256-byte
response buffer.
Reported-by: QcN3ep
Fixes GHSA-v6rf-jr7x-9hhp
Reported-by: Nora-Qiu
Fixes GHSA-p2v4-ghw2-mvq3
Closes#2573
