diff --git a/gtests/net/mptcp/add_addr/add_addr_client.pkt b/gtests/net/mptcp/add_addr/add_addr_client.pkt
index 15b5ecd5..d74532ad 100644
--- a/gtests/net/mptcp/add_addr/add_addr_client.pkt
+++ b/gtests/net/mptcp/add_addr/add_addr_client.pkt
@@ -27,7 +27,7 @@
 +0.0      <   .  1:1(0)  ack 101  win 256  <nop, nop, TS val 705 ecr 305, add_address addr[saddr] hmac=auto, dss dack8=101 dll=0 nocs>
 
 // ADD_ADDR echo (without hmac)
-+0.0      >   .  101:101(0)  ack 1         <nop, nop, TS val 494 ecr 700, add_address addr[saddr]          , dss dack4=1   dll=1 nocs>
++0.0      >   .  101:101(0)  ack 1         <nop, nop, TS val 494 ecr 700, add_address addr[saddr] addr_echo, dss dack4=1   dll=1 nocs>
 
 +0.0 close(3) = 0
 +0.0      >   .  101:101(0)  ack 1         <nop, nop, TS val 494 ecr 700,                                    dss dack4=1   dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>
diff --git a/gtests/net/mptcp/add_addr/add_addr_server.pkt b/gtests/net/mptcp/add_addr/add_addr_server.pkt
index 2b916632..900b9a5b 100644
--- a/gtests/net/mptcp/add_addr/add_addr_server.pkt
+++ b/gtests/net/mptcp/add_addr/add_addr_server.pkt
@@ -4,7 +4,7 @@
 
 // TODO(malsbat):
 +0     `ip mptcp endpoint flush`
-+0     `ip mptcp endpoint add 192.168.122.83 signal`
++0     `ip mptcp endpoint add 198.51.100.2 signal`
 
 +0     socket(..., SOCK_STREAM, IPPROTO_MPTCP) = 3
 +0     setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
@@ -17,9 +17,8 @@
 +0     accept(3, ..., ...) = 4
 
 // ADD_ADDR is sent directly (>= 5.12), not after first data (< 5.12)
-+0       >   .  1:1(0)        ack 1              <add_address addr[saddr] hmac=auto, dss dack4=1           ssn=1 dll=0 nocs>
-// TODO: support injecting ADD_ADDR echo
-//+0     <   .  1:1(0)        ack 1     win 257  <add_address addr[saddr],           dss dack8=1           ssn=1 dll=0 nocs>
++0       >   .  1:1(0)        ack 1              <add_address address_id=1 addr[ep=inet_addr("198.51.100.2")] hmac=auto, dss dack4=1 ssn=1 dll=0 nocs>
++0       <   .  1:1(0)        ack 1     win 257  <add_address address_id=1 addr[ep=inet_addr("198.51.100.2")] addr_echo,      dss dack8=1 ssn=1 dll=0 nocs>
 
 // read and ack 1 data segment
 +1.0     <  P.  1:1001(1000)  ack 1     win 450  <nop, nop,                          dss dack8=1    dsn8=1 ssn=1 dll=1000 nocs>
diff --git a/gtests/net/mptcp/fastclose/receive_fastclose_with_ack_multi_v4.pkt b/gtests/net/mptcp/fastclose/receive_fastclose_with_ack_multi_v4.pkt
index e973b5ec..7b85f424 100644
--- a/gtests/net/mptcp/fastclose/receive_fastclose_with_ack_multi_v4.pkt
+++ b/gtests/net/mptcp/fastclose/receive_fastclose_with_ack_multi_v4.pkt
@@ -15,9 +15,8 @@
 +0    accept(3, ..., ...) = 4
 
 // add_addr
-+0.0    >                                .  1:1(0)        ack 1                <add_address addr[saddr1] hmac=auto, dss dack4=1                    dll=0    nocs>
-// TODO: send echo bit
-// +0.0 <                                .  1:1(0)        ack 1     win 256    <add_address addr[saddr1],           dss dack8=1                    dll=0    nocs>
++0.0    >                                .  1:1(0)        ack 1                <add_address address_id=1 addr[saddr1] hmac=auto, dss dack4=1                    dll=0    nocs>
++0.0    <                                .  1:1(0)        ack 1     win 256    <add_address address_id=1 addr[saddr1] addr_echo, dss dack8=1                    dll=0    nocs>
 
 +0.2    <                               P.  1:1001(1000)  ack 1     win 450    <nop, nop,                           dss dack8=1    dsn8=1    ssn=1 dll=1000 nocs>
 +0.0    >                                .  1:1(0)        ack 1001                                                 <dss dack8=1001 nocs>
@@ -27,8 +26,8 @@
 
 
 // add another subflow.
-+0.5    <  addr[caddr1] > addr[saddr1]  S   0:0(0)                  win 65535  <mss 1460, nop, wscale 7, mp_join_syn     address_id=2 token=sha256_32(skey)>
-+0.0    >                               S.  0:0(0)        ack 1                <mss 1460, nop, wscale 8, mp_join_syn_ack address_id=0 sender_hmac=auto>
++0.5    <  addr[caddr1] > addr[saddr1]  S   0:0(0)                  win 65535  <mss 1460, nop, wscale 7, mp_join_syn     address_id=1 token=sha256_32(skey)>
++0.0    >                               S.  0:0(0)        ack 1                <mss 1460, nop, wscale 8, mp_join_syn_ack address_id=1 sender_hmac=auto>
 +0.0    <                                .  1:1(0)        ack 1     win 256                             <mp_join_ack                  sender_hmac=auto>
 +0.0    >                                .  1:1(0)        ack 1                          <dss dack8=1001 nocs>
 
diff --git a/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_multi_v4.pkt b/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_multi_v4.pkt
index 74903d6d..e35dd3cd 100644
--- a/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_multi_v4.pkt
+++ b/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_multi_v4.pkt
@@ -16,8 +16,7 @@
 
 // add_addr
 +0.0    >                                .  1:1(0)        ack 1                <add_address addr[saddr1] hmac=auto, dss dack4=1                    dll=0    nocs>
-// TODO: send echo bit
-// +0.0 <                                .  1:1(0)        ack 1     win 256    <add_address addr[saddr1],           dss dack8=1                    dll=0    nocs>
++0.0    <                                .  1:1(0)        ack 1     win 256    <add_address addr[saddr1] addr_echo, dss dack8=1                    dll=0    nocs>
 
 +0.2    <                               P.  1:1001(1000)  ack 1     win 450    <nop, nop,                           dss dack8=1    dsn8=1    ssn=1 dll=1000 nocs>
 +0.0    >                                .  1:1(0)        ack 1001                                                 <dss dack8=1001 nocs>
diff --git a/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_v4.pkt b/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_v4.pkt
index 88445035..e34c236a 100644
--- a/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_v4.pkt
+++ b/gtests/net/mptcp/fastclose/receive_fastclose_with_rst_v4.pkt
@@ -30,8 +30,7 @@
 +0.0     <                                .  1:1(0)           ack 1      win 256                             <mp_join_ack                  sender_hmac=auto>
 
 +0.0     >                                .  1:1(0)           ack 1                 <add_address addr[saddr1] hmac=auto, dss dack8=1001 nocs>
-// TODO: send echo bit
-// +0.0  <                                .  1:1(0)           ack 1      win 256    <add_address addr[saddr1],           dss dack8=1    nocs>
++0.0     <                                .  1:1(0)           ack 1      win 256    <add_address addr[saddr1] addr_echo, dss dack8=1    nocs>
 
 // more data, resend.  should work now.
 +0.0     <                               P.  1:1001(1000)     ack 1      win 450    <nop, nop,                           dss dack8=1    dsn8=1001 ssn=1    dll=1000 nocs>
diff --git a/gtests/net/mptcp/mp_join/mp_join_client_v4.pkt b/gtests/net/mptcp/mp_join/mp_join_client_v4.pkt
index 07616a74..f65cc030 100644
--- a/gtests/net/mptcp/mp_join/mp_join_client_v4.pkt
+++ b/gtests/net/mptcp/mp_join/mp_join_client_v4.pkt
@@ -22,7 +22,7 @@
 
 
 +0.0    >               > addr[saddr1]  S   0:0(0)                        <mss 1460, sackOK, TS val 448955294 ecr 0,         nop, wscale 8, mp_join_syn     address_id=0 token=sha256_32(skey)>
-+0.0    >               > addr[saddr0]   .  3:3(0)      ack 1             <nop, nop,         TS val 448955294 ecr 448955294, add_address addr[saddr1],           dss dack4=1   nocs>
++0.0    >               > addr[saddr0]   .  3:3(0)      ack 1             <nop, nop,         TS val 448955294 ecr 448955294, add_address addr[saddr1] addr_echo, dss dack4=1   nocs>
 +0.0    <                               S.  0:0(0)      ack 1  win 65535  <mss 1460, sackOK, TS val 448955294 ecr 448955294, nop, wscale 8, mp_join_syn_ack address_id=1 sender_hmac=auto>
 +0.0    >                                .  1:1(0)      ack 1             <nop, nop,         TS val 448955294 ecr 448955294,                mp_join_ack                  sender_hmac=auto>
 
diff --git a/gtests/net/mptcp/mp_join/mp_join_server_v4.pkt b/gtests/net/mptcp/mp_join/mp_join_server_v4.pkt
index a8899a6b..9306cede 100644
--- a/gtests/net/mptcp/mp_join/mp_join_server_v4.pkt
+++ b/gtests/net/mptcp/mp_join/mp_join_server_v4.pkt
@@ -2,6 +2,7 @@
 `../common/defaults.sh`
 
 +0    `../common/server.sh`
++0    `nstat -r -n`
 
 +0.0  socket(..., SOCK_STREAM, IPPROTO_MPTCP) = 3
 +0.0  setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
@@ -17,22 +18,18 @@
 +0    accept(3, ..., ...) = 4
 
 // add_addr
-+0.0    >                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address addr[saddr1] hmac=auto, dss dack4=1 dll=0 nocs>
-// TODO: send echo bit
-// +0.0 <                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address addr[saddr1],           dss dack8=1 dll=0 nocs>
-
-
-+0.2    <                               P.  1:3(2)  ack 1  win 256    <nop, nop,         TS val 4074418292 ecr 4074410674,                mpcapable v1 flags[flag_h] key[skey, ckey] mpcdatalen 2, nop, nop>
-// MP_CAPABLE carrying data are acked with 64-bit, safer not knowing if the
-// sender will use a DSN on 64-bit or 32-bit. Later we can use the lower 32 bits
-+0.0    >                                .  1:1(0)  ack 3             <nop, nop,         TS val 4074418293 ecr 4074418292,                dss dack8=3 dll=0 nocs>
++0.0    >                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address address_id=1 addr[saddr1] hmac=auto, dss dack4=1 dll=0 nocs>
++0.0    <                                .  1:1(0)  ack 1  win 256    <                                                    add_address address_id=1 addr[saddr1] addr_echo, dss dack8=1 dll=0 nocs>
 
 // create subflow
-+0.0    <  addr[caddr1] > addr[saddr1]  S   0:0(0)         win 65535  <mss 1460, sackOK, TS val 448955294  ecr 0,          nop, wscale 8, mp_join_syn     backup=1 address_id=2 token=sha256_32(skey)>
-+0.0    >                               S.  0:0(0)  ack 1             <mss 1460, sackOK, TS val 448955294  ecr 448955294,  nop, wscale 8, mp_join_syn_ack backup=1 address_id=0 sender_hmac=auto>
++0.0    <  addr[caddr1] > addr[saddr1]  S   0:0(0)         win 65535  <mss 1460, sackOK, TS val 448955294  ecr 0,          nop, wscale 8, mp_join_syn     backup=1 address_id=1 token=sha256_32(skey)>
++0.0    >                               S.  0:0(0)  ack 1             <mss 1460, sackOK, TS val 448955294  ecr 448955294,  nop, wscale 8, mp_join_syn_ack backup=1 address_id=1 sender_hmac=auto>
 +0.0    <                                .  1:1(0)  ack 1  win 256    <nop, nop,         TS val 448955294  ecr 448955294,                 mp_join_ack                           sender_hmac=auto>
-+0.0    >                                .  1:1(0)  ack 1             <nop, nop,         TS val 448955294  ecr 448955294,                 dss dack8=3 nocs>
+
++0.0    >                                .  1:1(0)  ack 1             <nop, nop,         TS val 448955294  ecr 448955294,                 dss dack4=1 nocs>
+
+
 
 // close connection
-+0.0    <  addr[caddr0] > addr[saddr0]  F.  3:3(0)  ack 1  win 256    <nop, nop,         TS val 4074418292 ecr 4074418293,                dss dack4=1 dsn8=3 ssn=0 dll=1 nocs fin, nop, nop>
-+0.0    <               > addr[saddr1]  F.  1:1(0)  ack 1  win 256    <nop, nop,         TS val 448955294  ecr 448955294>
++0.0    <  addr[caddr0] > addr[saddr0]  F.  1:1(0)  ack 1  win 256    <nop, nop,         TS val 4074418292 ecr 4074418293,                dss dack4=1 dsn8=1 ssn=0 dll=1 nocs fin, nop, nop>
++0.0    <               > addr[saddr1]  F.  1:1(0)  ack 1  win 256
diff --git a/gtests/net/mptcp/mp_prio/mp_prio_server_v4.pkt b/gtests/net/mptcp/mp_prio/mp_prio_server_v4.pkt
index 04fe4c11..634b23cc 100644
--- a/gtests/net/mptcp/mp_prio/mp_prio_server_v4.pkt
+++ b/gtests/net/mptcp/mp_prio/mp_prio_server_v4.pkt
@@ -17,9 +17,8 @@
 +0    accept(3, ..., ...) = 4
 
 // add_addr
-+0.0    >                                .  1:1(0)        ack 1             <nop, nop, TS val 4074418293 ecr 4074418292, add_address addr[saddr1] hmac=auto, dss dack4=1  dll=0 nocs>
-// TODO: send echo bit
-// +0.0 <                                .  1:1(0)        ack 1             <nop, nop, TS val 4074418293 ecr 4074418292, add_address addr[saddr1],           dss dack8=1  dll=0 nocs>
++0.0    >                                .  1:1(0)        ack 1             <nop, nop, TS val 4074418293 ecr 4074418292, add_address address_id=1 addr[saddr1] hmac=auto, dss dack4=1  dll=0 nocs>
++0.0    <                                .  1:1(0)        ack 1  win 256    <                                            add_address address_id=1 addr[saddr1] addr_echo, dss dack8=1  dll=0 nocs>
 
 +0.2    <                               P.  1:3(2)        ack 1  win 256    <nop, nop, TS val 4074418292 ecr 4074410674,                        mpcapable v1 flags[flag_h] key[skey, ckey] mpcdatalen 2, nop, nop>
 // MP_CAPABLE carrying data are acked with 64-bit, safer not knowing if the
@@ -33,7 +32,7 @@
 +0.0  read(4, ..., 2) = 2
 
 // create subflow
-+0.0    <  addr[caddr1] > addr[saddr1]  S   0:0(0)               win 65535  <mss 1460, sackOK, TS val 448955294 ecr 0,         nop, wscale 8, mp_join_syn     backup=1 address_id=2 token=sha256_32(skey)>
++0.0    <  addr[caddr1] > addr[saddr1]  S   0:0(0)               win 65535  <mss 1460, sackOK, TS val 448955294 ecr 0,         nop, wscale 8, mp_join_syn     backup=1 address_id=1 token=sha256_32(skey)>
 +0.0    >                               S.  0:0(0)        ack 1             <mss 1460, sackOK, TS val 448955294 ecr 448955294, nop, wscale 8, mp_join_syn_ack backup=1 address_id=0 sender_hmac=auto>
 +0.0    <                                .  1:1(0)        ack 1  win 256    <nop, nop, TS val 448955294 ecr 448955294,                        mp_join_ack sender_hmac=auto>
 +0.0    >                                .  1:1(0)        ack 1             <nop, nop, TS val 448955294 ecr 448955294,                        dss dack4=5 nocs>
diff --git a/gtests/net/mptcp/mp_reset/mp_reset_multi_v4.pkt b/gtests/net/mptcp/mp_reset/mp_reset_multi_v4.pkt
index be551729..d397485c 100644
--- a/gtests/net/mptcp/mp_reset/mp_reset_multi_v4.pkt
+++ b/gtests/net/mptcp/mp_reset/mp_reset_multi_v4.pkt
@@ -16,7 +16,7 @@
 
 // add_addr
 +0.0    >                                .  1:1(0)           ack 1                <add_address addr[saddr1] hmac=auto, dss dack4=1                       dll=0    nocs>
-// +0.0 <                                .  1:1(0)           ack 1     win 256    <add_address addr[saddr1],           dss dack8=1                       dll=0    nocs>
++0.0    <                                .  1:1(0)           ack 1     win 256    <add_address addr[saddr1] addr_echo, dss dack8=1                       dll=0    nocs>
 
 +0.2    <                               P.  1:1001(1000)     ack 1     win 450    <nop, nop,                           dss dack8=1    dsn8=1    ssn=1    dll=1000 nocs>
 +0.0    >                                .  1:1(0)           ack 1001                                                 <dss dack8=1001 nocs>
diff --git a/gtests/net/mptcp/syscalls/accept_v4.pkt b/gtests/net/mptcp/syscalls/accept_v4.pkt
index eb70394c..b2d1e0eb 100644
--- a/gtests/net/mptcp/syscalls/accept_v4.pkt
+++ b/gtests/net/mptcp/syscalls/accept_v4.pkt
@@ -18,8 +18,7 @@
 
 // add_addr
 +0.0    >                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address addr[saddr1] hmac=auto, dss dack4=1 dll=0 nocs>
-// TODO: send echo bit
-// +0.0 <                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address addr[saddr1],           dss dack8=1 dll=0 nocs>
++0.0    <                                .  1:1(0)  ack 1             <nop, nop,         TS val 4074418293 ecr 4074418292, add_address addr[saddr1] addr_echo, dss dack8=1 dll=0 nocs>
 
 +0.2    <                               P.  1:3(2)  ack 1  win 256    <nop, nop,         TS val 4074418292 ecr 4074410674,                mpcapable v1 flags[flag_h] key[skey, ckey] mpcdatalen 2, nop, nop>
 // MP_CAPABLE carrying data are acked with 64-bit, safer not knowing if the
diff --git a/gtests/net/packetdrill/lexer.l b/gtests/net/packetdrill/lexer.l
index 0556e9ea..9c92a1fd 100644
--- a/gtests/net/packetdrill/lexer.l
+++ b/gtests/net/packetdrill/lexer.l
@@ -254,6 +254,7 @@ backup			return BACKUP;
 mp_join_syn_ack	return MP_JOIN_SYN_ACK;
 mp_join_ack		return MP_JOIN_ACK;
 add_address		return ADD_ADDRESS;
+addr_echo		return ADDR_ECHO;
 port			return PORT;
 add_addr_ipv4	return ADD_ADDR_IPV4;
 add_addr_ipv6	return ADD_ADDR_IPV6;
diff --git a/gtests/net/packetdrill/parser.y b/gtests/net/packetdrill/parser.y
index da7ee908..530492b0 100644
--- a/gtests/net/packetdrill/parser.y
+++ b/gtests/net/packetdrill/parser.y
@@ -851,7 +851,7 @@ struct tcp_option *dss_do_dsn_dack( int dack_type, int dack_val,
 %token <reserved> DSS DACK4 DSN4 DACK8 DSN8 FIN SSN DLL NOCS CKSUM ADDR ADDRESS_ID BACKUP TOKEN AUTO RAND
 %token <reserved> TRUNC_R64_HMAC TRUNC_R64_HMAC_SHA1 TRUNC_R64_HMAC_SHA256
 %token <reserved> SENDER_HMAC TRUNC_L64_HMAC FULL_160_HMAC SHA1_32 SHA256_32 ADD_ADDR_HMAC
-%token <reserved> ADD_ADDRESS ADD_ADDR_IPV4 ADD_ADDR_IPV6 PORT MP_FAIL
+%token <reserved> ADD_ADDRESS ADD_ADDR_IPV4 ADD_ADDR_IPV6 PORT MP_FAIL ADDR_ECHO
 %token <reserved> REMOVE_ADDRESS ADDRESSES_ID LIST_ID
 %token <reserved> MP_PRIO
 %token <reserved> MP_TCPRST
@@ -1953,7 +1953,8 @@ SENDER_HMAC '=' TRUNC_L64_HMAC '(' INTEGER ')' {
 ;
 
 add_addr_hmac
-: {
+:
+ADDR_ECHO {
         $$.auto_conf = false;
         $$.hash = UNDEFINED;
 }