x/crypto/ssh: invalid packet length, packet too large #54719

marklaptenok · 2022-08-28T13:50:55Z

What version of Go are you using (`go version`)?

$ go version
go version go1.18.5 freebsd/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (`go env`)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="freebsd"
GOINSECURE=""
GOMODCACHE="/root/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="freebsd"
GOPATH="/root/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go118"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go118/pkg/tool/freebsd_amd64"
GOVCS=""
GOVERSION="go1.18.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="cc"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/root/deployer/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build2722818596=/tmp/go-build -gno-record-gcc-switches"

What did you do?

func send(private_key_path string, ftp_server_address_port string, ftp_user string) {
        key, error := os.ReadFile(private_key_path)
	if error != nil {
		logger.Fatalf("Can't open the private key to connect to runtime environment: %s", error.Error())
	}

	signer, error := ssh.ParsePrivateKeyWithPassphrase(key, []byte(ftp_user))
	if error != nil {
		logger.Fatalf("Can't parse the private key to connect to runtime environment: %s", error.Error())
	}

	ssh_configuration := &ssh.ClientConfig{
		User: ftp_user,
		Auth: []ssh.AuthMethod{
			ssh.PublicKeys(signer),
		},
		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		Timeout:         0,
		ClientVersion:   "Deployer",
	}

	ssh_connection, error := ssh.Dial("tcp", ftp_server_address_port, ssh_configuration)
	if error != nil {
		logger.Fatalf("Can't connect to %s as %s: %s", ftp_server_address_port, ftp_user, error.Error())
	}
	defer ssh_connection.Close()

	logger.Printf("Connected to %s as %s", ftp_server_address_port, ftp_user)

         // ...
}

What did you expect to see?

"Connected to 10.0.3.15:22 as test_env"

What did you see instead?

"Can't connect to 10.0.3.15:22 as test_env: ssh: handshake failed: ssh: invalid packet length, packet too large"

The text was updated successfully, but these errors were encountered:

seankhliao · 2022-08-28T14:17:52Z

golang.org/x/crypto/ssh version?
sshd version?
sshd config?

without information on how to reproduce this report isn't very actionable

marklaptenok · 2022-08-29T15:30:13Z

@seankhliao
golang.org/x/crypto/ssh version

go get: upgraded golang.org/x/crypto v0.0.0-20220817201139-bc19a97f63c8 => v0.0.0-20220826181053-bd7e27e6170d
go get: upgraded golang.org/x/sys v0.0.0-20220818161305-2296e01440c6 => v0.0.0-20220825204002-c680a09ffe64

sshd version

OpenSSH_7.9p1, OpenSSL 1.1.1l-freebsd  24 Aug 2021

sshd config

#Port 22
#AddressFamily any
ListenAddress 10.0.3.15
#ListenAddress ::

#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
PermitRootLogin no
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile	/etc/ssh/authorized_keys

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# Change to yes to enable built-in password authentication.
PasswordAuthentication no
#PermitEmptyPasswords no

# Change to no to disable PAM authentication
#ChallengeResponseAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

# Set this to 'no' to disable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
#UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#UseBlacklist no
#VersionAddendum FreeBSD-20200214

# no default banner path
#Banner none

# override default of no subsystems
Subsystem	sftp	/usr/libexec/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server

without information on how to reproduce this report isn't very actionable

Yes, I know. I am a software engineer. I provide information you ask. No more. To not overload you with the details.

marklaptenok · 2022-09-09T14:23:38Z

Hi @seankhliao, when the research will start? When could I estimate to have some results on the incident?

5hir0kur0 · 2022-09-30T10:53:21Z

Hi @marklaptenok

I had the same problem and found this issue through a Google search. In my case, I could fix it by setting the ClientVersion (in the ssh.ClientConfig struct) to a string starting with SSH-2.0-.
Maybe you could try that as well. You can also just omit the ClientVersion in which case the default value of "SSH-2.0-Go" will be used.
Hope this helps.

marklaptenok · 2022-11-06T11:28:26Z

Hi @5hir0kur0 ,

thank you for a workaround. It works for me.

akmistry · 2022-11-15T05:52:15Z

It's not a workaround, it's a requirement of the SSH protocol. The server config has this comment:

// Note that [RFC 4253 section 4.2](https://rfc-editor.org/rfc/rfc4253.html#section-4.2) requires that this string start with
// "SSH-2.0-".

This comment should probably be added to ClientConfig.ClientVersion too.

joedian · 2022-11-15T18:38:15Z

Fixed.

marklaptenok · 2022-11-20T10:34:37Z

It's not a workaround, it's a requirement of the SSH protocol. The server config has this comment:
// Note that [RFC 4253 section 4.2](https://rfc-editor.org/rfc/rfc4253.html#section-4.2) requires that this string start with
// "SSH-2.0-".
This comment should probably be added to ClientConfig.ClientVersion too.

Thank you for your remark. I have not known this.

seankhliao added WaitingForInfo NeedsInvestigation labels Aug 28, 2022

seankhliao changed the title ~~affected/package: golang.org/x/crypto/ssh~~ x/crypto/ssh: invalid packet length, packet too large Aug 28, 2022

gopherbot added this to the Unreleased milestone Aug 28, 2022

joedian removed WaitingForInfo NeedsInvestigation labels Nov 15, 2022

ianlancetaylor closed this as completed Nov 15, 2022

golang locked and limited conversation to collaborators Nov 20, 2023

gopherbot added the FrozenDueToAge label Nov 20, 2023

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x/crypto/ssh: invalid packet length, packet too large #54719

x/crypto/ssh: invalid packet length, packet too large #54719

marklaptenok commented Aug 28, 2022

seankhliao commented Aug 28, 2022

marklaptenok commented Aug 29, 2022

marklaptenok commented Sep 9, 2022

5hir0kur0 commented Sep 30, 2022

marklaptenok commented Nov 6, 2022

akmistry commented Nov 15, 2022

joedian commented Nov 15, 2022

marklaptenok commented Nov 20, 2022

x/crypto/ssh: invalid packet length, packet too large #54719

x/crypto/ssh: invalid packet length, packet too large #54719

Comments

marklaptenok commented Aug 28, 2022

What version of Go are you using (go version)?

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

What did you do?

What did you expect to see?

What did you see instead?

seankhliao commented Aug 28, 2022

marklaptenok commented Aug 29, 2022

marklaptenok commented Sep 9, 2022

5hir0kur0 commented Sep 30, 2022

marklaptenok commented Nov 6, 2022

akmistry commented Nov 15, 2022

joedian commented Nov 15, 2022

marklaptenok commented Nov 20, 2022

What version of Go are you using (`go version`)?

What operating system and processor architecture are you using (`go env`)?