org.apache.catalina.valves
Class RemoteIpValve

java.lang.Object
  org.apache.catalina.util.LifecycleBase
      org.apache.catalina.util.LifecycleMBeanBase
          org.apache.catalina.valves.ValveBase
              org.apache.catalina.valves.RemoteIpValve

All Implemented Interfaces:

MBeanRegistration, Contained, Lifecycle, Valve

public class RemoteIpValve
extends ValveBase

Tomcat port of mod_remoteip, this valve replaces the apparent client remote IP address and hostname for the request with the IP address list presented by a proxy or a load balancer via a request headers (e.g. "X-Forwarded-For").

Another feature of this valve is to replace the apparent scheme (http/https) and server port with the scheme presented by a proxy or a load balancer via a request header (e.g. "X-Forwarded-Proto").

This valve proceeds as follows:

If the incoming request.getRemoteAddr() matches the valve's list of internal proxies :

• Loop on the comma delimited list of IPs and hostnames passed by the preceding load balancer or proxy in the given request's Http header named $remoteIpHeader (default value x-forwarded-for). Values are processed in right-to-left order.
• For each ip/host of the list:
  • if it matches the internal proxies list, the ip/host is swallowed
  • if it matches the trusted proxies list, the ip/host is added to the created proxies header
  • otherwise, the ip/host is declared to be the remote ip and looping is stopped.
• If the request http header named $protocolHeader (e.g. x-forwarded-for) equals to the value of protocolHeaderHttpsValue configuration parameter (default https) then request.isSecure = true, request.scheme = https and request.serverPort = 443. Note that 443 can be overwritten with the $httpsServerPort configuration parameter.

Configuration parameters:

RemoteIpValve property	Description	Equivalent mod_remoteip directive	Format	Default Value
remoteIpHeader	Name of the Http Header read by this valve that holds the list of traversed IP addresses starting from the requesting client	RemoteIPHeader	Compliant http header name	x-forwarded-for
internalProxies	Regular expression that matches the IP addresses of internal proxies. If they appear in the remoteIpHeader value, they will be trusted and will not appear in the proxiesHeader value	RemoteIPInternalProxy	Regular expression (in the syntax supported by java.util.regex)	10\.\d{1,3}\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3} By default, 10/8, 192.168/16, 169.254/16 and 127/8 are allowed ; 172.16/12 has not been enabled by default because it is complex to describe with regular expressions
proxiesHeader	Name of the http header created by this valve to hold the list of proxies that have been processed in the incoming remoteIpHeader	RemoteIPProxiesHeader	Compliant http header name	x-forwarded-by
trustedProxies	Regular expression that matches the IP addresses of trusted proxies. If they appear in the remoteIpHeader value, they will be trusted and will appear in the proxiesHeader value	RemoteIPTrustedProxy	Regular expression (in the syntax supported by java.util.regex)
protocolHeader	Name of the http header read by this valve that holds the flag that this request	N/A	Compliant http header name like X-Forwarded-Proto, X-Forwarded-Ssl or Front-End-Https	null
protocolHeaderHttpsValue	Value of the protocolHeader to indicate that it is an Https request	N/A	String like https or ON	https
httpServerPort	Value returned by ServletRequest.getServerPort() when the protocolHeader indicates http protocol	N/A	integer	80
httpsServerPort	Value returned by ServletRequest.getServerPort() when the protocolHeader indicates https protocol	N/A	integer	443

This Valve may be attached to any Container, depending on the granularity of the filtering you wish to perform.

Regular expression vs. IP address blocks: mod_remoteip allows to use address blocks (e.g. 192.168/16) to configure RemoteIPInternalProxy and RemoteIPTrustedProxy ; as Tomcat doesn't have a library similar to apr_ipsubnet_test, RemoteIpValve uses regular expression to configure internalProxies and trustedProxies in the same fashion as RequestFilterValve does.

Sample with internal proxies

RemoteIpValve configuration:

 <Valve
   className="org.apache.catalina.valves.RemoteIpValve"
   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
   remoteIpHeader="x-forwarded-for"
   remoteIpProxiesHeader="x-forwarded-by"
   protocolHeader="x-forwarded-proto"
   />

Request values:

property	Value Before RemoteIpValve	Value After RemoteIpValve
request.remoteAddr	192.168.0.10	140.211.11.130
request.header['x-forwarded-for']	140.211.11.130, 192.168.0.10	null
request.header['x-forwarded-by']	null	null
request.header['x-forwarded-proto']	https	https
request.scheme	http	https
request.secure	false	true
request.serverPort	80	443

Note : x-forwarded-by header is null because only internal proxies as been traversed by the request. x-forwarded-by is null because all the proxies are trusted or internal.

Sample with trusted proxies

RemoteIpValve configuration:

 <Valve
   className="org.apache.catalina.valves.RemoteIpValve"
   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
   remoteIpHeader="x-forwarded-for"
   remoteIpProxiesHeader="x-forwarded-by"
   trustedProxies="proxy1|proxy2"
   />

Request values:

property	Value Before RemoteIpValve	Value After RemoteIpValve
request.remoteAddr	192.168.0.10	140.211.11.130
request.header['x-forwarded-for']	140.211.11.130, proxy1, proxy2	null
request.header['x-forwarded-by']	null	proxy1, proxy2

Note : proxy1 and proxy2 are both trusted proxies that come in x-forwarded-for header, they both are migrated in x-forwarded-by header. x-forwarded-by is null because all the proxies are trusted or internal.

Sample with internal and trusted proxies

RemoteIpValve configuration:

 <Valve
   className="org.apache.catalina.valves.RemoteIpValve"
   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
   remoteIpHeader="x-forwarded-for"
   remoteIpProxiesHeader="x-forwarded-by"
   trustedProxies="proxy1|proxy2"
   />

Request values:

property	Value Before RemoteIpValve	Value After RemoteIpValve
request.remoteAddr	192.168.0.10	140.211.11.130
request.header['x-forwarded-for']	140.211.11.130, proxy1, proxy2, 192.168.0.10	null
request.header['x-forwarded-by']	null	proxy1, proxy2

Note : proxy1 and proxy2 are both trusted proxies that come in x-forwarded-for header, they both are migrated in x-forwarded-by header. As 192.168.0.10 is an internal proxy, it does not appear in x-forwarded-by. x-forwarded-by is null because all the proxies are trusted or internal.

Sample with an untrusted proxy

RemoteIpValve configuration:

 <Valve
   className="org.apache.catalina.valves.RemoteIpValve"
   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
   remoteIpHeader="x-forwarded-for"
   remoteIpProxiesHeader="x-forwarded-by"
   trustedProxies="proxy1|proxy2"
   />

Request values:

property	Value Before RemoteIpValve	Value After RemoteIpValve
request.remoteAddr	192.168.0.10	untrusted-proxy
request.header['x-forwarded-for']	140.211.11.130, untrusted-proxy, proxy1	140.211.11.130
request.header['x-forwarded-by']	null	proxy1

Note : x-forwarded-by holds the trusted proxy proxy1. x-forwarded-by holds 140.211.11.130 because untrusted-proxy is not trusted and thus, we can not trust that untrusted-proxy is the actual remote ip. request.remoteAddr is untrusted-proxy that is an IP verified by proxy1.

Field Summary

Fields inherited from class org.apache.catalina.valves.ValveBase

asyncSupported, container, containerLog, next, sm

Fields inherited from class org.apache.catalina.util.LifecycleMBeanBase

mserver

Fields inherited from interface org.apache.catalina.Lifecycle

AFTER_DESTROY_EVENT, AFTER_INIT_EVENT, AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_DESTROY_EVENT, BEFORE_INIT_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, CONFIGURE_START_EVENT, CONFIGURE_STOP_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT

Constructor Summary

RemoteIpValve()
Default constructor that ensures ValveBase.ValveBase(boolean) is called with true.

Method Summary

protected static String[]	commaDelimitedListToStringArray(String commaDelimitedStrings) Convert a given comma delimited String into an array of String
int	getHttpServerPort()
int	getHttpsServerPort()
String	getInfo() Return descriptive information about this Valve implementation.
String	getInternalProxies()
String	getPortHeader() Obtain the name of the HTTP header used to override the value returned by Request.getServerPort() and (optionally depending on {link isChangeLocalPort() Request.getLocalPort().
String	getProtocolHeader()
String	getProtocolHeaderHttpsValue()
String	getProxiesHeader()
String	getRemoteIpHeader()
boolean	getRequestAttributesEnabled()
String	getTrustedProxies()
void	invoke(Request request, Response response) The implementation-specific logic represented by this Valve.
boolean	isChangeLocalPort()
protected static String	listToCommaDelimitedString(List<String> stringList) Convert an array of strings in a comma delimited string
void	setChangeLocalPort(boolean changeLocalPort)
void	setHttpServerPort(int httpServerPort) Server Port value if the protocolHeader is not null and does not indicate HTTP Default value : 80
void	setHttpsServerPort(int httpsServerPort) Server Port value if the protocolHeader indicates HTTPS Default value : 443
void	setInternalProxies(String internalProxies) Regular expression that defines the internal proxies.
void	setPortHeader(String portHeader) Set the name of the HTTP header used to override the value returned by Request.getServerPort() and (optionally depending on {link isChangeLocalPort() Request.getLocalPort().
void	setProtocolHeader(String protocolHeader) Header that holds the incoming protocol, usally named X-Forwarded-Proto.
void	setProtocolHeaderHttpsValue(String protocolHeaderHttpsValue) Case insensitive value of the protocol header to indicate that the incoming http request uses SSL.
void	setProxiesHeader(String proxiesHeader) The proxiesHeader directive specifies a header into which mod_remoteip will collect a list of all of the intermediate client IP addresses trusted to resolve the actual remote IP.
void	setRemoteIpHeader(String remoteIpHeader) Name of the http header from which the remote ip is extracted.
void	setRequestAttributesEnabled(boolean requestAttributesEnabled) Should this valve set request attributes for IP address, Hostname, protocol and port used for the request?
void	setTrustedProxies(String trustedProxies) Regular expression defining proxies that are trusted when they appear in the remoteIpHeader header.

Methods inherited from class org.apache.catalina.valves.ValveBase

backgroundProcess, event, getContainer, getDomainInternal, getNext, getObjectNameKeyProperties, initInternal, isAsyncSupported, setAsyncSupported, setContainer, setNext, startInternal, stopInternal, toString

Methods inherited from class org.apache.catalina.util.LifecycleMBeanBase

destroyInternal, getDomain, getObjectName, postDeregister, postRegister, preDeregister, preRegister, register, setDomain, unregister

Methods inherited from class org.apache.catalina.util.LifecycleBase

addLifecycleListener, destroy, findLifecycleListeners, fireLifecycleEvent, getState, getStateName, init, removeLifecycleListener, setState, setState, start, stop

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RemoteIpValve

public RemoteIpValve()

Default constructor that ensures ValveBase.ValveBase(boolean) is called with true.

Method Detail

commaDelimitedListToStringArray

protected static String[] commaDelimitedListToStringArray(String commaDelimitedStrings)

Convert a given comma delimited String into an array of String

Returns:

array of String (non null)

listToCommaDelimitedString

protected static String listToCommaDelimitedString(List<String> stringList)

Convert an array of strings in a comma delimited string

getHttpsServerPort

public int getHttpsServerPort()

getHttpServerPort

public int getHttpServerPort()

isChangeLocalPort

public boolean isChangeLocalPort()

setChangeLocalPort

public void setChangeLocalPort(boolean changeLocalPort)

getPortHeader

public String getPortHeader()

Obtain the name of the HTTP header used to override the value returned by Request.getServerPort() and (optionally depending on {link isChangeLocalPort() Request.getLocalPort().

Returns:

The HTTP header name

setPortHeader

public void setPortHeader(String portHeader)

Set the name of the HTTP header used to override the value returned by Request.getServerPort() and (optionally depending on {link isChangeLocalPort() Request.getLocalPort().

Parameters:

portHeader - The HTTP header name

getInfo

public String getInfo()

Return descriptive information about this Valve implementation.

Specified by:

getInfo in interface Valve

Overrides:

getInfo in class ValveBase

getInternalProxies

public String getInternalProxies()

Returns:

Regular expression that defines the internal proxies

See Also:

setInternalProxies(String)

getProtocolHeader

public String getProtocolHeader()

Returns:

the protocol header (e.g. "X-Forwarded-Proto")

See Also:

setProtocolHeader(String)

getProtocolHeaderHttpsValue

public String getProtocolHeaderHttpsValue()

Returns:

the value of the protocol header for incoming https request (e.g. "https")

See Also:

setProtocolHeaderHttpsValue(String)

getProxiesHeader

public String getProxiesHeader()

Returns:

the proxies header name (e.g. "X-Forwarded-By")

See Also:

setProxiesHeader(String)

getRemoteIpHeader

public String getRemoteIpHeader()

Returns:

the remote IP header name (e.g. "X-Forwarded-For")

See Also:

setRemoteIpHeader(String)

getRequestAttributesEnabled

public boolean getRequestAttributesEnabled()

Returns:

true if the attributes will be logged, otherwise false

See Also:

setRequestAttributesEnabled(boolean)

getTrustedProxies

public String getTrustedProxies()

Returns:

Regular expression that defines the trusted proxies

See Also:

setTrustedProxies(String)

invoke

public void invoke(Request request,
                   Response response)
            throws IOException,
                   ServletException

The implementation-specific logic represented by this Valve. See the Valve description for the normal design patterns for this method.

This method MUST be provided by a subclass.

Specified by:

invoke in interface Valve

Specified by:

invoke in class ValveBase

Parameters:

request - The servlet request to be processed

response - The servlet response to be created

Throws:

IOException - if an input/output error occurs

ServletException - if a servlet error occurs

setHttpServerPort

public void setHttpServerPort(int httpServerPort)

Server Port value if the protocolHeader is not null and does not indicate HTTP

Default value : 80

setHttpsServerPort

public void setHttpsServerPort(int httpsServerPort)

Server Port value if the protocolHeader indicates HTTPS

Default value : 443

setInternalProxies

public void setInternalProxies(String internalProxies)

Regular expression that defines the internal proxies.

Default value : 10\.\d{1,3}\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254.\d{1,3}.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3}

setProtocolHeader

public void setProtocolHeader(String protocolHeader)

Header that holds the incoming protocol, usally named X-Forwarded-Proto. If null, request.scheme and request.secure will not be modified.

Default value : null

setProtocolHeaderHttpsValue

public void setProtocolHeaderHttpsValue(String protocolHeaderHttpsValue)

Case insensitive value of the protocol header to indicate that the incoming http request uses SSL.

Default value : https

setProxiesHeader

public void setProxiesHeader(String proxiesHeader)

The proxiesHeader directive specifies a header into which mod_remoteip will collect a list of all of the intermediate client IP addresses trusted to resolve the actual remote IP. Note that intermediate RemoteIPTrustedProxy addresses are recorded in this header, while any intermediate RemoteIPInternalProxy addresses are discarded.

Name of the http header that holds the list of trusted proxies that has been traversed by the http request.

The value of this header can be comma delimited.

Default value : X-Forwarded-By

setRemoteIpHeader

public void setRemoteIpHeader(String remoteIpHeader)

Name of the http header from which the remote ip is extracted.

The value of this header can be comma delimited.

Default value : X-Forwarded-For

Parameters:

remoteIpHeader -

setRequestAttributesEnabled

public void setRequestAttributesEnabled(boolean requestAttributesEnabled)

Should this valve set request attributes for IP address, Hostname, protocol and port used for the request? This are typically used in conjunction with the AccessLog which will otherwise log the original values. Default is true. The attributes set are:

• org.apache.catalina.AccessLog.RemoteAddr
• org.apache.catalina.AccessLog.RemoteHost
• org.apache.catalina.AccessLog.Protocol
• org.apache.catalina.AccessLog.ServerPort

Parameters:

requestAttributesEnabled - true causes the attributes to be set, false disables the setting of the attributes.

setTrustedProxies

public void setTrustedProxies(String trustedProxies)

Regular expression defining proxies that are trusted when they appear in the remoteIpHeader header.

Default value : empty list, no external proxy is trusted.