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Implement support for the PROXY protocol #108

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Implement support for the PROXY protocol #108

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677510a
Implement support for the PROXY protocol
tsipinakis Mar 4, 2022
787e648
Add proxy IP to audit log
tsipinakis May 13, 2022
4b167ff
Add missing handshake descriptions to auditlog
tsipinakis May 13, 2022
0815681
Wrap proxyproto in separate package
tsipinakis May 13, 2022
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3 changes: 3 additions & 0 deletions config/ssh.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,9 @@ type SSHConfig struct {
// See https://tools.ietf.org/html/rfc4253#page-4 section 4.2. Protocol Version Exchange
// The trailing CR and LF characters should NOT be added to this string.
ServerVersion SSHServerVersion `json:"serverVersion" yaml:"serverVersion" default:"SSH-2.0-ContainerSSH"`
// AllowedProxies is a list of IP addresses or CIDR ranges that are allowed to use the
// PROXY protocol to override the connection originator IP address.
AllowedProxies []string `json:"allowedProxies" yaml:"allowedProxies"`
// Ciphers are the ciphers offered to the client.
Ciphers SSHCipherList `json:"ciphers" yaml:"ciphers" default:"[\"chacha20-poly1305@openssh.com\",\"aes256-gcm@openssh.com\",\"aes128-gcm@openssh.com\",\"aes256-ctr\",\"aes192-ctr\",\"aes128-ctr\"]" comment:"SSHCipher suites to use"`
// KexAlgorithms are the key exchange algorithms offered to the client.
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1 change: 1 addition & 0 deletions go.mod
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Expand Up @@ -18,6 +18,7 @@ require (
github.com/mitchellh/mapstructure v1.4.3
github.com/opencontainers/image-spec v1.0.2
github.com/oschwald/geoip2-golang v1.5.0
github.com/pires/go-proxyproto v0.6.1
github.com/qdm12/reprint v0.0.0-20200326205758-722754a53494
github.com/stretchr/testify v1.7.0
golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
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2 changes: 2 additions & 0 deletions go.sum
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Expand Up @@ -628,6 +628,8 @@ github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/9
github.com/pelletier/go-toml v1.8.1 h1:1Nf83orprkJyknT6h7zbuEGUEjcyVlCxSUGTENmNCRM=
github.com/pelletier/go-toml v1.8.1/go.mod h1:T2/BmBdy8dvIRq1a/8aqjN41wvWlN4lrapLU/GW4pbc=
github.com/peterbourgon/diskv v2.0.1+incompatible/go.mod h1:uqqh8zWWbv1HBMNONnaR/tNboyR3/BZd58JJSHlUSCU=
github.com/pires/go-proxyproto v0.6.1 h1:EBupykFmo22SDjv4fQVQd2J9NOoLPmyZA/15ldOGkPw=
github.com/pires/go-proxyproto v0.6.1/go.mod h1:Odh9VFOZJCf9G8cLW5o435Xf1J95Jw9Gw5rnCjcwzAY=
github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
github.com/pkg/errors v0.8.1-0.20171018195549-f15c970de5b7/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
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22 changes: 19 additions & 3 deletions internal/sshserver/serverImpl.go
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Expand Up @@ -15,6 +15,7 @@ import (
messageCodes "github.com/containerssh/libcontainerssh/message"
"github.com/containerssh/libcontainerssh/service"
"golang.org/x/crypto/ssh"
"github.com/pires/go-proxyproto"

@ghost ghost Apr 19, 2022

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This is a third party library and should be abstracted away with its own package, including tests so it can be replaced if need be.

)

type serverImpl struct {
Expand Down Expand Up @@ -54,11 +55,20 @@ func (s *serverImpl) RunWithLifecycle(lifecycle service.Lifecycle) error {
Control: s.socketControl,
}

useProxy := len(s.cfg.AllowedProxies) > 0

netListener, err := listenConfig.Listen(lifecycle.Context(), "tcp", s.cfg.Listen)
if err != nil {
s.lock.Unlock()
return messageCodes.Wrap(err, messageCodes.ESSHStartFailed, "failed to start SSH server on %s", s.cfg.Listen)
}
if useProxy {

@ghost ghost Apr 19, 2022

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It seems to me that PROXY is a wrapper protocol like many others (e.g. websocket). We should consider creating a generic abstraction for wrapper protocols.

@tsipinakis tsipinakis May 13, 2022

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I don't foresee having any other wrapping protocols in-front of the ssh server since, we can consider that if it's necessary further down the line.

policy := proxyproto.MustStrictWhiteListPolicy(s.cfg.AllowedProxies)
netListener = &proxyproto.Listener{
Listener: netListener,
Policy: policy,
}
}
s.listenSocket = netListener
s.lock.Unlock()
if err := s.handler.OnReady(); err != nil {
Expand All @@ -84,7 +94,13 @@ func (s *serverImpl) RunWithLifecycle(lifecycle service.Lifecycle) error {
break
}
s.wg.Add(1)
go s.handleConnection(tcpConn)
logger := s.logger
if useProxy {
proxyConn := tcpConn.(*proxyproto.Conn)
proxyIp := proxyConn.Raw().RemoteAddr()
logger = logger.WithLabel("fromProxy", proxyIp.(*net.TCPAddr).IP.String())
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}
go s.handleConnection(logger, tcpConn)
}
lifecycle.Stopping()
s.shuttingDown = true
Expand Down Expand Up @@ -501,10 +517,10 @@ func (s *serverImpl) createPasswordCallback(
return passwordCallback
}

func (s *serverImpl) handleConnection(conn net.Conn) {
func (s *serverImpl) handleConnection(logger log.Logger, conn net.Conn) {
addr := conn.RemoteAddr().(*net.TCPAddr)
connectionID := GenerateConnectionID()
logger := s.logger.
logger = logger.
WithLabel("remoteAddr", addr.IP.String()).
WithLabel("connectionId", connectionID)
handlerNetworkConnection, err := s.handler.OnNetworkConnection(*addr, connectionID)
Expand Down