RFC 4030
The Authentication Suboption for the Dynamic Host Configuration Protocol (DHCP) Relay Agent Option
The Authentication Suboption for the Dynamic Host Configuration Protocol (DHCP) Relay Agent Option 🎀
Okay, bestie, let's get the basics down first 💅
- RFC number: 4030
- Series: Network Working Group
- Authors: M. Stapp (Cisco Systems, Inc.) and T. Lemon (Nominum, Inc.) 👯
- Category: Standards Track ✅
- Date: March 2005 📅
- Obsoletes / Updates: this one doesn't list anything it obsoletes or updates 🌸
Status of This Memo 📜
Okay so this is a standards track protocol for the whole Internet community 🌐, and it's literally asking for discussion and suggestions for improvements 💬. If you want to know where this protocol sits in the standardization process, check the current edition of the "Internet Official Protocol Standards" (STD 1) 📋. Distribution of this memo is unlimited 🦋.
Copyright Notice ©️
Copyright (C) The Internet Society (2005). 💖
Abstract ✨
So the Dynamic Host Configuration Protocol (DHCP) Relay Agent Information Option (RFC 3046) is how a DHCP Relay Agent and a DHCP server pass info back and forth 🔁. This spec adds an authentication suboption to that option, and it carries a keyed hash in its payload 🔐. The result? Relayed DHCP messages get data integrity and replay protection, and that's iconic 👑.
Table of Contents 🗂️
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Terminology . . . . . . . . . . . . . . . . . . 3
3. DHCP Terminology . . . . . . . . . . . . . . . . . . . . . . 4
4. Suboption Format . . . . . . . . . . . . . . . . . . . . . . 4
5. Replay Detection . . . . . . . . . . . . . . . . . . . . . . 5
6. The Relay Identifier Field . . . . . . . . . . . . . . . . . 5
7. Computing Authentication Information . . . . . . . . . . . . 6
7.1. The HMAC-SHA1 Algorithm . . . . . . . . . . . . . . . 6
8. Procedures for Sending Messages . . . . . . . . . . . . . . 7
8.1. Replay Detection . . . . . . . . . . . . . . . . . . . 7
8.2. Packet Preparation . . . . . . . . . . . . . . . . . . 8
8.3. Checksum Computation . . . . . . . . . . . . . . . . . 8
8.4. Sending the Message . . . . . . . . . . . . . . . . . 8
9. Procedures for Processing Incoming Messages . . . . . . . . 8
9.1. Initial Examination . . . . . . . . . . . . . . . . . 8
9.2. Replay Detection Check . . . . . . . . . . . . . . . . 9
9.3. Testing the Checksum . . . . . . . . . . . . . . . . . 9
10. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 9
10.1. Receiving Messages from Other Relay Agents . . . . . . 10
10.2. Sending Messages to Servers . . . . . . . . . . . . . 10
10.3. Receiving Messages from Servers . . . . . . . . . . . 10
11. DHCP Server Behavior . . . . . . . . . . . . . . . . . . . . 10
11.1. Receiving Messages from Relay Agents . . . . . . . . . 10
11.2. Sending Reply Messages to Relay Agents . . . . . . . . 11
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 11
13. Security Considerations . . . . . . . . . . . . . . . . . . 11
13.1. The Key ID Field . . . . . . . . . . . . . . . . . . . 12
13.2. Protocol Vulnerabilities . . . . . . . . . . . . . . . 12
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
15.1. Normative References . . . . . . . . . . . . . . . . . 13
15.2. Informative References . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 151. Introduction 💖
Okay so DHCP (RFC 2131 [6]) hands out IP addresses and configuration info to IPv4 clients 🖥️. It also has a relay-agent capability (RFC 951 [7], RFC 1542 [8]) where processes inside the network infrastructure catch broadcast messages from clients and forward them to servers as unicast messages 📬. In networks like DOCSIS data-over-cable and xDSL, it's been really useful for the relay agent to add info to the DHCP message before forwarding it, using the relay-agent information option (RFC 3046 [1]) 🧚. That info often shapes what the server decides about the addresses and configuration parameters the client should get 🎯. Because the server leans on relay-agent data so much, that data is super important, and it makes the trust relationship between the relay agent and the server a big deal 🫶.
The existing DHCP Authentication spec (RFC 3118) [9] only covers communication between the DHCP client and server 🙅. Relay-agent info gets added after the client has already sent its message, so the DHCP Authentication spec explicitly leaves relay-agent data out of that authentication 💀.
So the goal here is to define methods a relay agent can use to:
- protect the integrity of relayed DHCP messages,
- provide replay protection for those messages, and
- leverage existing mechanisms, such as DHCP Authentication.
To hit those goals, this spec introduces a brand new relay-agent suboption: the Authentication suboption 🎀. Its format is very similar to the DHCP Authentication option, and its cryptographic methods and hash computation are similar too, which is honestly so smart 🧠.
Relay agents that want to make sure the data they put in the Relay Agent option hasn't been messed with will include the Authentication suboption 🔒. They get configured with the parameters needed to generate cryptographic checksums of the data in the DHCP messages they forward to DHCP servers 🔑. A DHCP server set up to process the Authentication suboption uses the info in it to verify the checksum, and it only keeps processing the relay agent information option if the checksum is valid ✅. If the server sends a response, it includes an Authentication suboption in that response message 📨. And relay agents check the checksums in server responses to decide whether to forward those responses along 🦋.
2. Requirements Terminology 📚
Okay, the key words are the bossy ones that tell you how strict a rule is 👑. In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [2] 🧚.
3. DHCP Terminology 🌷
This doc uses the terms "DHCP server" (or "server") and "DHCP client" (or "client") the way RFC 2131 [6] defines them 🖥️. The term "DHCP relay agent" refers to a "BOOTP relay agent" as defined in RFC 2131 📬.
4. Suboption Format 🧩
Here's the layout, bestie. Each row is 32 bits wide, so this is basically the suboption as a picture 🖼️:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length | Algorithm | MBZ | RDM |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection cont. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Relay Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Authentication Information |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+The code for the suboption is 8 🔢. The length field counts the lengths of the algorithm, the RDM, and every suboption field after them, in octets 📏.
The Algorithm field says which algorithm generates the authentication info 🔐.
Four bits are reserved for future use 🌙. These bits SHOULD be set to zero, and they MUST NOT be used when the suboption is processed 🚫.
The Replay Detection Method (RDM) field says which method generates the Replay Detection Data 🔁.
The Replay Detection field holds a value used to catch replayed messages, and it gets interpreted according to the RDM 🕵️.
The Relay Identifier field is for relay agents that don't set giaddr, as described in RFC 3046 [1], section 2.1 🪪.
The Authentication Information field holds the data needed to communicate algorithm-specific parameters, plus the checksum 🧁. The checksum is usually a digest of the data in the DHCP packet, computed with the method the Algorithm field specifies 💜.
5. Replay Detection 🔁
Okay, this is the replay-detection mechanism, and the big idea is that a receiver can figure out whether a message has a valid replay token value 🕰️. The default RDM, with value 1, says the Replay Detection field holds an increasing counter value 📈. The receiver keeps a replay counter for each sender, and it rejects any message with an authentication suboption whose Replay Detection counter value is less than or equal to the last valid value 🚫. DHCP servers MAY identify relay agents by giaddr value or by other data in the message (e.g., data in other relay agent suboptions) 🔍. Relay agents identify DHCP servers by source IP address 🌐. If the message's replay detection value and the checksum are both valid, the receiver updates its notion of the last valid replay counter value for that sender 🎉.
All implementations MUST support the default RDM 💅. Additional methods may be defined in the future, following the process described in section 12 🔮.
Receivers SHOULD perform the replay-detection check before testing the checksum 🧐. The keyed hash calculation is likely to be much more expensive than the replay-detection value check 💸.
DISCUSSION: This places a burden on the receiver to maintain some run-time state (the most-recent valid counter value) for each sender, but the number of members in a DHCP agent-server system is unlikely to be unmanageably large. 🌈
6. The Relay Identifier Field ✨
Okay so the Relay Agent Information Option [1] spec lets a relay agent slap a relay agent option onto relayed messages without setting the giaddr field 🎀. When that happens, the server that finally gets the message needs a steady identifier so it can tie per-sender stuff (like the Key ID and the replay-detection counters) to the right sender 🔍. That's where the Relay ID field comes in!
A relay that adds a relay agent information option and sets giaddr MUST NOT set the Relay ID field 🙅♀️. A relay that doesn't set giaddr MAY be configured to put a value in the Relay ID field 🌸. If it's set up to use that field, it MAY be configured with a specific value, or it MAY be configured to generate one from some other data, like its MAC or IP addresses 🧚. And if a relay makes up its own Relay ID value, it SHOULD pick one it can regenerate reliably, e.g., across reboots 💅.
Servers that process an Authentication Suboption SHOULD use the giaddr value to identify the sender whenever giaddr is set 💖. Servers MAY be configured to use some other data in the message to identify the sender instead 🦋. If giaddr isn't set, the server SHOULD use the Relay ID field, as long as it's nonzero ✨. And if neither giaddr nor the Relay ID field is set, the server MAY be configured to use some other data in the message, or it MAY increment an error counter 💀.
7. Computing Authentication Information 🔐
The Authentication Information field holds a keyed hash that the sender makes 🫶. Every algorithm handles the data in the DHCP messages the same way, which is honestly so iconic 👑. The sender and receiver both compute a hash over a buffer with every byte of the DHCP message, including the fixed DHCP message header, the DHCP options, and the relay agent suboptions 🧁. There are a few exceptions though, so pay attention! 👀
The hops field MUST be set to zero for the computation, because its value can change in transit 🔄. The giaddr field MUST also be set to zero for the computation, because it can get modified in networks where one relay agent adds the relay agent option but a different relay agent sets giaddr (see RFC 3046, section 2.1) 🌈. Also, since the relay agent option is itself part of the computation, the 'authentication information' field in the Authentication suboption is set to all zeros 🙈. The relay agent option length, the Authentication suboption length, and the other Authentication suboption fields are all included in the computation 💜.
All implementations MUST support Algorithm 1, the HMAC-SHA1 algorithm 💅. Other algorithms may be defined in the future by following the process described in section 12 🔮.
7.1. The HMAC-SHA1 Algorithm
Algorithm 1 is assigned to the HMAC [3] protocol by using the SHA-1 [4] hash function 🧠. This algorithm needs a shared secret key configured at both the relay agent and the DHCP server 🗝️. Each shared key has a 32-bit Key Identifier attached, and that identifier rides along in the first 4 bytes of the Authentication Information field of the Authentication suboption 🎀. The HMAC-SHA1 computation spits out a 20-byte hash value, which goes into the Authentication Information field right after the Key ID ✨.
When Algorithm 1 is being used, the Authentication suboption looks like this:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | 38 |0 0 0 0 0 0 0 1| MBZ | RDM |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection cont. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Relay Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| HMAC-SHA1 (160 bits) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+The suboption length is 38 🔢. The RDM and Replay Detection fields work exactly as section 5 says 📖. The Relay ID field gets set the way section 6 describes 🌸. The sender sets the Key ID to the ID of the key it used for the checksum, as an integer in network byte order 🧮. The HMAC result comes right after the Key ID 💫.
The Key ID is only there so the sender and receiver can pick a shared secret when a bunch of secrets are floating around among a network's relays and DHCP servers 🗂️. Key ID values are totally a local configuration thing, and they only have to be unique locally 🏠. This spec doesn't define any semantics for Key ID values or put any requirements on them, so no drama there 🙌.
8. Procedures for Sending Messages 📤
8.1. Replay Detection
The sender grabs a replay-detection counter value based on the RDM it's using 🔢. If the sender is using RDM 1, which is the default RDM, the value MUST be greater than any value sent before 📈. No going backwards, bestie 💅!
8.2. Packet Preparation
The sender sets giaddr and hops to all zeros 0️⃣. Then it tacks the relay agent information option onto the client's packet, Authentication suboption included 🎁. It picks an appropriate Replay Detection value 🎯. The sender puts its identifier in the Relay ID field if it needs to, or sets the field to all zeros 🆔. Next it sets the suboption length, drops the Replay Detection value into the Replay Detection field, and sets the algorithm to the number of the one it's using 🔧. If it's using HMAC-SHA1, it sets the Key ID field to the right value 🔑. Last step, it sets the checksum field to all zeros 🫧. Other algorithms may have their own extra prep steps 🌟.
8.3. Checksum Computation
The sender computes the checksum across the entire DHCP message using the algorithm it picked 🧮. Then it puts the result into the Authentication Information field of the Authentication suboption 💌.
8.4. Sending the Message
The sender restores the hops and giaddr values and then sends the message 🚀. Ta-da!
9. Procedures for Processing Incoming Messages 📥
9.1. Initial Examination
The receiver looks at the giaddr value and checks whether the packet has the relay agent information option 👀. It uses its configuration to figure out whether it should expect an Authentication suboption 🧐. The receiver MUST support a configuration that lets it drop incoming messages that don't have a valid relay agent information option and Authentication suboption 🛑. No sneaky messages allowed!
If the receiver decides the Authentication suboption is there and that it should process it, it uses the data in the message to figure out which algorithm, key, and RDM to validate with 🔍. If it can't work out which algorithm, key, and RDM to use, or it doesn't support the value the message indicates, it SHOULD drop the message 🗑️. This could mean a misconfiguration that's blocking clients from getting service, so receivers MAY try to tell their administrators or log an error message 📣.
9.2. Replay Detection Check
The receiver checks the RDM field first 🔎. Receivers MUST discard messages with RDM values they don't support 🚫. Since that might point to a misconfiguration at the sender, an attempt SHOULD be made to let the administrator know, by bumping an error counter or writing a log message 📝. If the receiver does support the RDM, it checks the Replay Detection field using the procedures in the RDM and in section 5 🧩. If the Replay value isn't valid, the receiver MUST drop the message 🙅♀️.
⚠️ Important tea: at this point the receiver MUST NOT update its notion of the last valid Replay Detection value for the sender! Until the checksum has been tested, the Replay Detection field can't be trusted 🥺. If the receiver trusted the Replay Detection value without testing the checksum, a malicious host could send a replayed message with a super high Replay Detection value and trick the receiver into rejecting the sender's legit values 😱. Not on my watch!
9.3. Testing the Checksum
The receiver gets the packet ready for checksum testing by setting the giaddr and hops fields to zero, and by setting the Authentication Information field of the suboption to all zeros 🧼. Using the algorithm and key associated with the sender, the receiver computes a hash of the message 🧪. It then compares its result with the value that was sent ⚖️. If the checksums don't match, the receiver MUST drop the message 💥. Otherwise, it updates its notion of the last valid Replay Detection value for the sender and processes the message 🎉.
10. Relay Agent Behavior 🧚
DHCP Relay agents are usually configured with the addresses of one or more DHCP servers 🗺️. A relay agent that implements this suboption needs an algorithm number for each server, along with the right credentials (i.e., keys) 🔐. Relay implementations SHOULD support a configuration that says all relayed messages should include the Authentication suboption 💫. Using the Authentication suboption SHOULD be disabled by default 🙅♀️. Relay agents MAY support a configuration saying certain destination servers support the Authentication suboption and others don't 🌗. Relay agents MAY support one algorithm number and one key for all DHCP servers, or they MAY support different algorithms and keys for each server 🔑.
10.1. Receiving Messages from Other Relay Agents
Sometimes one relay agent adds the relay agent option and then forwards the DHCP message to another relay agent 🔁. For example, a layer-2 switch might be directly connected to a client and forward messages to an aggregating router, which sets giaddr and then forwards the message to a DHCP server 🖧. When a DHCP relay that implements the Authentication suboption receives a message, it MAY use the procedures in section 9 to verify the source of the message before forwarding it 🕵️♀️.
10.2. Sending Messages to Servers
When the relay agent gets a broadcast packet from a client, it figures out which DHCP servers (or other relay agents) should get copies of the message 📬. If the relay agent is set up to include the Authentication suboption, it decides which Algorithm and RDM to use, and then it runs through the steps in section 8 🏃♀️.
10.3. Receiving Messages from Servers
When the relay agent receives a message, it checks its configuration to see whether it expects the message to have a relay agent information option and an Authentication suboption 🔍. The relay agent MAY be configured to drop response messages that don't have the Authentication suboption 🗑️. After that, the relay agent follows the procedures in section 9 💖.
11. DHCP Server Behavior ✨
Okay so servers can totally be talking to a whole crowd of relay agents at once 🫶 Server implementations MAY support a setup where one algorithm and one key get paired with every relay agent, and servers MAY also support a setup where each relay agent gets its own algorithm and key 🔑
11.1. Receiving Messages from Relay Agents
When a DHCP server that implements the Authentication suboption gets a message, it runs through the steps in section 9. Easy peasy 💅
11.2. Sending Reply Messages to Relay Agents
Once the server has a reply ready to go, it looks at the incoming request and its own config to decide whether the reply should carry a relay agent information option and an Authentication suboption 🎀 If the server is set up to include the Authentication suboption, it picks the Algorithm and RDM to use and then follows the steps in section 8.
DISCUSSION: this server behavior is a teeny bit different from RFC 3046 [1], section 2.2 🙈 The Authentication suboption doesn't get echoed back from the server to the relay. Instead, the server makes its own suboption.
12. IANA Considerations 🌸
Section 4 defines a brand new suboption for the DHCP relay agent option, called the Authentication Suboption. IANA gave it a new suboption code from the relay agent option suboption number space 🦋
This spec also introduces two brand new number spaces, one for the Authentication suboption's 'Algorithm' field and one for its 'Replay Detection Method' field. IANA has set these up and will keep maintaining them 📋
The Algorithm identifier is a one-byte value. Algorithm value 0 is reserved. Algorithm value 1 is assigned to the HMAC-SHA1 keyed hash, as defined in section 7.1. Any additional algorithm values will be allocated and assigned through IETF consensus, as defined in RFC 2434 [5] 💜
The RDM identifier is a four-bit value. RDM value 0 is reserved. RDM value 1 is assigned to the use of a monotonically increasing counter value, as defined in section 5. Any additional RDM values will be allocated and assigned through IETF consensus, as defined in RFC 2434 [5] ✨
13. Security Considerations 🔥
Okay this part is serious bestie 😭 This spec describes a protocol that adds source authentication and message integrity protection to the messages between DHCP relay agents and DHCP servers 🛡️
Using this protocol puts a brand new computational burden on relay agents and servers, because they have to do cryptographic hash calculations every time they send and receive messages. That burden can add latency to DHCP message exchanges 💀 Relay agents are involved whenever clients reboot, so periods of really high reboot activity mean the most messages have to get processed. During a cable MSO head-end reboot event, for example, the time it takes for every client to get served might go up 😩
13.1. The Key ID Field
The Authentication suboption has a four-byte Key ID, following the example of the DHCP Authentication RFC 🔑 Other authentication protocols, like DNS TSIG [10], use a key name. A key name is more flexible and potentially more human readable than a key ID. DHCP servers may well be set up to use key names for DNS updates with TSIG, so it might simplify server config if some of the key management for both protocols could be shared 🧚
On the other hand, it's crucial to keep the size expansion from the relay agent information option as small as possible. Named keys would take up more physical space and would make suboption encoding and parsing more complicated. That's why the spec uses a fixed-length Key ID instead of a variable-length key name 💅
13.2. Protocol Vulnerabilities
Because DHCP runs over UDP, messages between relays and servers might get delivered in a different order than they were generated 🌀 The replay-detection mechanism will make receivers drop packets that show up 'late', which leads to client retries. Most clients already handle retries, so this shouldn't be a massive issue, but senders will still do computational work that gets wasted if their messages get reordered 🙈
The DHC WG has developed two documents about authenticating DHCP relay agent options, so they can handle different deployment scenarios: this document and "Authentication of Relay Agent Options Using IPsec" [11] 🦋 As section 11 notes, the Authentication suboption can be used without pairwise keys between each relay and each DHCP server. In deployments where IPsec is readily available and pairwise keys can be managed efficiently, using IPsec as described in that document may be the better fit. If IPsec isn't available, or there are multiple relay agents whose multiple keys need managing, the protocol described here may be the better fit. Like with any situation where two options are available, local network administration can pick whichever is more appropriate 👑 Because the relay agents and the DHCP server are all in the same administrative domain, the right mechanism can be configured on every interoperating DHCP server element ✨
14. Acknowledgements 🫶
The need for this spec was made clear by comments from Thomas Narten and John Schnizlein, and Josh Littlefield suggested using the DHCP Authentication option format, at IETF 53 🌈
15. References 📚
15.1. Normative References
[1] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046,
January 2001.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[3] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing
for Message Authentication", RFC 2104, February 1997.
[4] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1
(SHA1)", RFC 3174, September 2001.
[5] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.15.2. Informative References
[6] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[7] Croft, W. and J. Gilmore, "Bootstrap Protocol", RFC 951,
September 1985.
[8] Wimer, W., "Clarifications and Extensions for the Bootstrap
Protocol", RFC 1542, October 1993.
[9] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
RFC 3118, June 2001.
[10] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. Wellington,
"Secret Key Transaction Authentication for DNS (TSIG)", RFC
2845, May 2000.
[11] Droms, R., "Authentication of Relay Agent Options Using IPsec",
Work in Progress, February 2004.Authors' Addresses 🎀
Mark Stapp
Cisco Systems, Inc.
1414 Massachusetts Ave.
Boxborough, MA 01719
USA
Phone: 978.936.0000
EMail: mjs@cisco.com
Ted Lemon
Nominum, Inc.
950 Charter St.
Redwood City, CA 94063
USA
EMail: Ted.Lemon@nominum.comFull Copyright Statement 💖
Copyright (C) The Internet Society (2005).
This document is subject to the rights, licenses and restrictions in BCP 78, and except as set forth there, the authors keep all their rights.
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