From draft-ietf-ipsecme-rfc4307bis-18 [1]:

2.2.  Type 2 - IKEv2 Pseudo-random Function Transforms

                ...
                | PRF_HMAC_MD5      | MUST NOT |         |
                +-------------------+----------+---------+

But it looks like it actually is still supported if I am reading it correctly:

000 "test": 10.16.41.25<10.16.41.25>...10.16.46.52<10.16.46.52>; erouted; eroute owner: #2
000 "test":     oriented; my_ip=unset; their_ip=unset
000 "test":   xauth us:none, xauth them:none,  my_username=[any]; their_username=[any]
000 "test":   our auth:secret, their auth:secret
000 "test":   modecfg info: us:none, them:none, modecfg policy:push, dns1:unset, dns2:unset, domain:unset, banner:unset, cat:unset;
000 "test":   labeled_ipsec:no;
000 "test":   policy_label:unset;
000 "test":   ike_life: 3600s; ipsec_life: 28800s; replay_window: 32; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 0;
000 "test":   retransmit-interval: 500ms; retransmit-timeout: 60s;
000 "test":   sha2-truncbug:no; initial-contact:no; cisco-unity:no; fake-strongswan:no; send-vendorid:no; send-no-esp-tfc:no;
000 "test":   policy: PSK+ENCRYPT+TUNNEL+PFS+UP+IKEV2_ALLOW+IKEV2_PROPOSE+SAREF_TRACK+IKE_FRAG_ALLOW+ESN_NO;
000 "test":   conn_prio: 32,32; interface: eth0; metric: 0; mtu: unset; sa_prio:auto; sa_tfc:none;
000 "test":   nflog-group: unset; mark: unset; vti-iface:unset; vti-routing:no; vti-shared:no;
000 "test":   dpd: action:hold; delay:0; timeout:0; nat-t: encaps:auto; nat_keepalive:yes; ikev1_natt:both
000 "test":   newest ISAKMP SA: #1; newest IPsec SA: #2;
000 "test":   IKE algorithms wanted: 3DES_CBC(5)_000-MD5(1)-MODP2048(14)
000 "test":   IKE algorithms found:  3DES_CBC(5)_192-MD5(1)-MODP2048(14)
000 "test":   IKEv2 algorithm newest: 3DES_192-AUTH_HMAC_MD5_96-PRF_HMAC_MD5-MODP2048
000 "test":   ESP algorithms wanted: 3DES(3)_000-SHA1(2)
000 "test":   ESP algorithms loaded: 3DES(3)_000-SHA1(2)
000 "test":   ESP algorithm newest: 3DES_192-HMAC_SHA1; pfsgroup=<Phase1>
000 #2: "test":500 STATE_V2_IPSEC_I (IPsec SA established); EVENT_SA_REPLACE in 27837s; newest IPSEC; eroute owner; isakmp#1; idle; import:admin initiate
000 #2: "test" esp.ca6cab5b.46.52 esp.2b9e65fa.41.25 tun.0.46.52 tun.0.41.25 ref=0 refhim=0 Traffic: ESPin=0B ESPout=0B! ESPmax=0B 
000 #1: "test":500 STATE_PARENT_I3 (PARENT SA established); EVENT_SA_REPLACE in 2847s; newest ISAKMP; isakmp#0; idle; import:admin initiate
000 #1: "test" ref=0 refhim=0 Traffic: 

Support of the other MUST NOT algorithms from rfc4307bis-18 is disabled.

[1] https://tools.ietf.org/html/draft-ietf-ipsecme-rfc4307bis-18#section-2.1

yes since too many people migrate ikev1 to ikev2 configs still. We are planning to remove it soon but not yet. Note that HMAC_Md5 is not a security issue 

Note it has been removed from all defaults in IKEv2, so it will never be used unless explicitly configured.

The same is true for MODP1024

Verified requirements from:

Algorithm Implementation Requirements and Usage Guidance for IKEv2 [1].

IKEv2 Encryption Algorithm Transforms
=====================================
ENCR_DES (MUST NOT)

- PASS, already not supported

Type 2 - IKEv2 Pseudo-random Function Transforms
================================================
PRF_HMAC_MD5 (MUST NOT)

- WAIVED, see comment #2 and #3

Type 3 - IKEv2 Integrity Algorithm Transforms
=============================================
AUTH_HMAC_MD5_96 (MUST NOT)

- PASS, MD5 is in default set but in 128 bit size (128-MD5(1))

AUTH_DES_MAC (MUST NOT)

- PASS, alrady not supported

AUTH_KPDK_MD5 (MUST NOT)

- PASS, already not supported

Type 4 - IKEv2 Diffie-Hellman Group Transforms
==============================================
768-bit MODP Group - DH1 (MUST NOT)

- PASS, already not supported

1024-bit MODP Group with 160-bit Prime Order Subgroup - DH22 (MUST NOT)

- PASS, not supported from 3.20 

1536-bit MODP Group (SHOULD NOT)

- PASS, modp1536 is supported but modp2048 is default

1024-bit MODP Group (SHOULD NOT)

- PASS, modp1024 is supported but modp2048 is default

2048-bit MODP Group with 224-bit Prime Order Subgroup - DH23 (SHOULD NOT)

- PASS, DH23 is supported but modp2048 is default

2048-bit MODP Group with 224-bit Prime Order Subgroup - DH24 (SHOULD NOT)

- PASS, DH24 is supported but modp2048 is default

[1] https://tools.ietf.org/html/draft-ietf-ipsecme-rfc4307bis-18

Note that DH22 support should be enabled in the spec file via USE_DH22=TRUE, but like DH23/DH24 it is not enabled per default unless manually configured.

I'm surprised MD5 is in any default set. It should not be. It should be supported for manual configuration in both IKEv1 and IKEv2, but not part of the default list?

Note that we now also support DH19, DH20 and DH21 now (the NIST ECC groups)

(In reply to Paul Wouters from comment #5)
> Note that DH22 support should be enabled in the spec file via USE_DH22=TRUE,
> but like DH23/DH24 it is not enabled per default unless manually configured.
> 
> I'm surprised MD5 is in any default set. It should not be. It should be
> supported for manual configuration in both IKEv1 and IKEv2, but not part of
> the default list?

May be I am reading it incorrectly, with ike=3des I see the following on both sides:

000 "test":   IKE algorithms wanted: 3DES_CBC(5)_000-SHA2_256(4)-MODP2048(14), 3DES_CBC(5)_000-SHA2_512(6)-MODP2048(14), 3DES_CBC(5)_000-SHA1(2)-MODP2048(14), 3DES_CBC(5)_000-MD5(1)-MODP2048(14)
000 "test":   IKE algorithms found:  3DES_CBC(5)_192-SHA2_256(4)-MODP2048(14), 3DES_CBC(5)_192-SHA2_512(6)-MODP2048(14), 3DES_CBC(5)_192-SHA1(2)-MODP2048(14), 3DES_CBC(5)_192-MD5(1)-MODP2048(14)

My understanding is that default set of IKEv2 integrity algorithms is: sha1_256(4), sha2_512(6), sha1(2) and MD5(1). Is that correct? BTW: I noticed that I incorrectly stated that the size od MD5 is 128. I actually do not know its size... :-/.

> Note that we now also support DH19, DH20 and DH21 now (the NIST ECC groups)

Verified requirements from:

Cryptographic Algorithm Implementation Requirements and Usage Guidance
for Encapsulating Security Payload (ESP) and Authentication Header (AH) [1]

ESP Encryption Algorithms
=========================
ENCR_DES_IV64 (MUST NOT)

- PASS, not supported

ENCR_DES (MUST NOT)

- PASS, not supported

ENCR_BLOWFISH (MUST NOT)

- PASS, not supported

ENCR_3IDEA (MUST NOT)

- PASS, not supported

ENCR_DES_IV32 (MUST NOT)

- PASS, not supported

ENCR_3DES (SHOULD NOT)

- PASS, default is AES_GCM_C_256-NONE

ESP and AH Authentication Algorithms
====================================
AUTH_NONE (MUST NOT)

- PASS, not supported

AUTH_HMAC_MD5_96 (MUST NOT)

- PASS, MD5 is supported from 128 bits

AUTH_DES_MAC (MUST NOT)

- PASS, not supported

AUTH_KPDK_MD5 (MUST NOT)

- PASS, not supported

[1] https://tools.ietf.org/html/draft-ietf-ipsecme-rfc7321bis-05#section-3

All cryptographic requirements related to this bug were verified. The only question to be clarified is that libreswan has MD5(1) (ie. algorithm IKE hash: id=1, name=OAKLEY_MD5, hashlen=16) in it default set of IKEv2 integrity algorithms despite that draft-ietf-ipsecme-rfc4307bis-18 speciefies AUTH_HMAC_MD5_96 as MUST NOT. Is MD5(1) equal to AUTH_HMAC_MD5_96? If so, what can we do about it?

[*] It is probably harmless since with ike=3des libreswan picks 3DES_192-AUTH_HMAC_SHA2_256_128-PRF_HMAC_SHA2_256-MODP2048.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2017:2101

(In reply to Ondrej Moriš from comment #8)
> All cryptographic requirements related to this bug were verified. The only
> question to be clarified is that libreswan has MD5(1) (ie. algorithm IKE
> hash: id=1, name=OAKLEY_MD5, hashlen=16) in it default set of IKEv2
> integrity algorithms despite that draft-ietf-ipsecme-rfc4307bis-18
> speciefies AUTH_HMAC_MD5_96 as MUST NOT. Is MD5(1) equal to
> AUTH_HMAC_MD5_96? If so, what can we do about it?
> 
> [*] It is probably harmless since with ike=3des libreswan picks
> 3DES_192-AUTH_HMAC_SHA2_256_128-PRF_HMAC_SHA2_256-MODP2048.

md5 is allowed but not in any default proposal set.