[strongSwan] Multiple SAs after rekey with traffic.

[Makarand Pradhan]

Good morning All,

I am facing an issue where the number of SAs keep on going up and then charon starts hogging the CPU. Will highly appreciate if anyone comment if I have misconfigured some parameter or if this is a known issue? Details below:

We are running Strongswan 5.9.5 on ppc64, Linux kernel 4.1.35.

It is noted that after a rekey timeout, a new SA is created(ESTABLISHED/INSTALLED). This happens only with traffic. Over a period of time, the number of SAs keep on increasing and then charon hogs the CPU.

Please find below the ipsec.conf that is being used and a log of my session showing the increasing number of SAs.

ipsec.conf

sh-4.3# cat /usr/local/etc/ipsec.conf
config setup
        charondebug=@all@
        cachecrls=yes
        uniqueids=yes
        strictcrlpolicy=no

#####IS5#####
conn policy1
        type=tunnel
        authby=secret
        auto=route
        keyexchange=ikev2
        ike=aes256-sha512-modp1536!
        aggressive=no
        ikelifetime=40m
        esp=aes256-sha256-modp2048!
        lifetime=20m
        right=172.16.100.101
        rightid=172.16.100.101
        rightsubnet=10.10.101.0/24
        left=172.16.100.1
        leftid=172.16.100.1
        leftsubnet=192.168.101.0/24
        dpddelay=60s
        mobike=no
        dpdaction=clear
        margintime=1m
        rekeyfuzz=0%
        leftcert=


e.g. Tunnel is set up:

sh-4.3# date
Mon May 16 09:15:33 UTC 2022
sh-4.3# ipsec status policy1
Routed Connections:
     policy1{1}:  ROUTED, TUNNEL, reqid 1
     policy1{1}:   192.168.101.0/24 === 10.10.101.0/24
Security Associations (1 up, 0 connecting):
     policy1[1]: ESTABLISHED 22 seconds ago, 172.16.100.1[172.16.100.1]...172.16.100.101[172.16.100.101]
     policy1{2}:  INSTALLED, TUNNEL, reqid 1, ESP SPIs: c4ee192d_i c18d1d43_o
     policy1{2}:   192.168.101.0/24 === 10.10.101.0/24

After some time:


sh-4.3# ipsec statusall policy1
Status of IKE charon daemon (weakSwan 5.9.5, Linux 4.1.35-rt41, ppc64):
  uptime: 77 minutes, since May 16 09:15:14 2022
  malloc: sbrk 2400256, mmap 0, used 354336, free 2045920
  worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, scheduled: 6
  loaded plugins: charon aes des blowfish rc2 sha2 sha1 md5 mgf1 random nonce x509 revocation constraints pubkey pkcs1 pkcs7 pkcs8 pkcs12 pgp dnskey sshkey pem fips-prf gmp curve25519 xcbc cmac hmac drbg attr kernel-netlink resolve socket-default farp stroke vici updown xauth-generic counters
Listening IP addresses:
  10.10.5.1
  192.168.101.11
  192.168.10.1
  192.168.50.2
  172.16.100.1
Connections:
     policy1:  172.16.100.1...172.16.100.101  IKEv2, dpddelay=60s
     policy1:   local:  [172.16.100.1] uses pre-shared key authentication
     policy1:   remote: [172.16.100.101] uses pre-shared key authentication
     policy1:   child:  192.168.101.0/24 === 10.10.101.0/24 TUNNEL, dpdaction=clear
Routed Connections:
     policy1{1}:  ROUTED, TUNNEL, reqid 1
     policy1{1}:   192.168.101.0/24 === 10.10.101.0/24
Security Associations (2 up, 0 connecting):
     policy1[2]: ESTABLISHED 38 minutes ago, 172.16.100.1[172.16.100.1]...172.16.100.101[172.16.100.101]
     policy1[2]: IKEv2 SPIs: 518b7019c5d03118_i* 74fe5d2949eaed95_r, pre-shared key reauthentication in 17 seconds
     policy1[2]: IKE proposal: AES_CBC_256/HMAC_SHA2_512_256/PRF_HMAC_SHA2_512/MODP_1536
     policy1{13}:  INSTALLED, TUNNEL, reqid 1, ESP SPIs: c9bab39c_i ca96f84a_o
     policy1{13}:  AES_CBC_256/HMAC_SHA2_256_128/MODP_2048, 0 bytes_i, 0 bytes_o, rekeying in 18 minutes
     policy1{13}:   192.168.101.0/24 === 10.10.101.0/24
     policy1[3]: ESTABLISHED 38 minutes ago, 172.16.100.1[172.16.100.1]...172.16.100.101[172.16.100.101]
     policy1[3]: IKEv2 SPIs: 005c2ec500a6a55d_i c00aead9fa60759a_r*, pre-shared key reauthentication in 17 seconds
     policy1[3]: IKE proposal: AES_CBC_256/HMAC_SHA2_512_256/PRF_HMAC_SHA2_512/MODP_1536
     policy1{12}:  INSTALLED, TUNNEL, reqid 1, ESP SPIs: c5fabaf0_i c5dad3ed_o
     policy1{12}:  AES_CBC_256/HMAC_SHA2_256_128/MODP_2048, 0 bytes_i, 0 bytes_o, rekeying in 18 minutes
     policy1{12}:   192.168.101.0/24 === 10.10.101.0/24

Kind rgds,
Makarand Pradhan
Senior Software Engineer.
iS5 Communications Inc.
5895 Ambler Dr,
Mississauga, Ontario
L4W 5B7
Main Line: +1-844-520-0588 Ext. 129
Direct Line: +1-289-724-2296
Cell: +1-226-501-5666
Fax:+1-289-401-5206
Email: makarandpradhan at is5com.com
Website: www.iS5Com.com

 
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